title: Heuristic

text: Gerd Gigerenzer and his research group argued that models of heuristics need to be formal to allow for predictions of behavior that can be tested. They study the fast and frugal heuristics in the "adaptive toolbox" of individuals or institutions, and the ecological rationality of these heuristics; that is, the conditions under which a given heuristic is likely to be successful. The descriptive study of the "adaptive toolbox" is done by observation and experiment, the prescriptive study of the ecological rationality requires mathematical analysis and computer simulation. Heuristics – such as the recognition heuristic, the take-the-best heuristic and fast-and-frugal trees – have been shown to be effective in predictions, particularly in situations of uncertainty. It is often said that heuristics trade accuracy for effort but this is only the case in situations of risk. Risk refers to situations where all possible actions, their outcomes and probabilities are known. In the absence of this information, that is under uncertainty, heuristics can achieve higher accuracy with lower effort. This finding, known as a less-is-more effect, would not have been found without formal models. The valuable insight of this program is that heuristics are effective not despite their simplicity — but because of it. Furthermore, Gigerenzer and Wolfgang Gaissmaier found that both individuals and organisations rely on heuristics in an adaptive way.


title: Heuristic

text: Heuristics, through greater refinement and research, have begun to be applied to other theories, or be explained by them. For example, the cognitive-experiential self-theory (CEST) also is an adaptive view of heuristic processing. CEST breaks down two systems that process information. At some times, roughly speaking, individuals consider issues rationally, systematically, logically, deliberately, effortfully and verbally. On other occasions, individuals consider issues intuitively, effortlessly, globally, and emotionally. From this perspective, heuristics are part of a larger experiential processing system that is often adaptive, but vulnerable to error in situations that require logical analysis.


title: Heuristic

text: In 2002, Daniel Kahneman and Shane Frederick proposed that cognitive heuristics work by a process called "attribute substitution", which happens without conscious awareness. According to this theory, when somebody makes a judgement (of a "target attribute") that is computationally complex, a more easily calculated "heuristic attribute" is substituted. In effect, a cognitively difficult problem is dealt with by answering a rather simpler problem, without being aware of this happening. This theory explains cases where judgements fail to show regression toward the mean. Heuristics can be considered to reduce the complexity of clinical judgments in health care.


title: Heuristic

text: Heuristics were also found to be used in the manipulation and creation of cognitive maps. "Cognitive maps" are internal representations of our physical environment, particularly associated with spatial relationships. These internal representations are used by our memory as a guide in our external environment. It was found that when questioned about maps imaging, distancing, etc., people commonly made distortions to images. These distortions took shape in the regularisation of images (i.e., images are represented as more like pure abstract geometric images, though they are irregular in shape).


title: Heuristic

text: There are several ways that humans form and use cognitive maps, with visual intake being an especially key part of mapping: the first is by using landmarks, whereby a person uses a mental image to estimate a relationship, usually distance, between two objects. The second is route-road knowledge, and is generally developed after a person has performed a task and is relaying the information of that task to another person. The third is a survey, whereby a person estimates a distance based on a mental image that, to them, might appear like an actual map. This image is generally created when a person's brain begins making image corrections. These are presented in five ways:


title: Heuristic

text: Another method of creating cognitive maps is by means of auditory intake based on verbal descriptions. Using the mapping based from a person's visual intake, another person can create a mental image, such as directions to a certain location.


title: Heuristic

text: A heuristic device is used when an entity "X" exists to enable understanding of, or knowledge concerning, some other entity "Y".


title: Heuristic

text: A good example is a model that, as it is never identical with what it models, is a heuristic device to enable understanding of what it models. Stories, metaphors, etc., can also be termed heuristic in this sense. A classic example is the notion of utopia as described in Plato's best-known work, "The Republic". This means that the "ideal city" as depicted in "The Republic" is not given as something to be pursued, or to present an orientation-point for development. Rather, it shows how things would have to be connected, and how one thing would lead to another (often with highly problematic results), if one opted for certain principles and carried them through rigorously.


title: Heuristic

text: "Heuristic" is also often used as a noun to describe a rule-of-thumb, procedure, or method. Philosophers of science have emphasised the importance of heuristics in creative thought and the construction of scientific theories. Seminal works include Karl Popper's "The Logic of Scientific Discovery" and others by Imre Lakatos, Lindley Darden, and William C. Wimsatt.


title: Heuristic

text: In legal theory, especially in the theory of law and economics, heuristics are used in the law when case-by-case analysis would be impractical, insofar as "practicality" is defined by the interests of a governing body.


title: Heuristic

text: The present securities regulation regime largely assumes that all investors act as perfectly rational persons.


title: Heuristic

text: In truth, actual investors face cognitive limitations from biases, heuristics, and framing effects. For instance, in all states in the United States the legal drinking age for unsupervised persons is 21 years, because it is argued that people need to be mature enough to make decisions involving the risks of alcohol consumption. However, assuming people mature at different rates, the specific age of 21 would be too late for some and too early for others. In this case, the somewhat arbitrary deadline is used because it is impossible or impractical to tell whether an individual is sufficiently mature for society to trust them with that kind of responsibility. Some proposed changes, however, have included the completion of an alcohol education course rather than the attainment of 21 years of age as the criterion for legal alcohol possession. This would put youth alcohol policy more on a case-by-case basis and less on a heuristic one, since the completion of such a course would presumably be voluntary and not uniform across the population.


title: Heuristic

text: The same reasoning applies to patent law. Patents are justified on the grounds that inventors must be protected so they have incentive to invent. It is therefore argued that it is in society's best interest that inventors receive a temporary government-granted monopoly on their idea, so that they can recoup investment costs and make economic profit for a limited period. In the United States, the length of this temporary monopoly is 20 years from the date the patent application was filed, though the monopoly does not actually begin until the application has matured into a patent. However, like the drinking-age problem above, the specific length of time would need to be different for every product to be efficient. A 20-year term is used because it is difficult to tell what the number should be for any individual patent. More recently, some, including University of North Dakota law professor Eric E. Johnson, have argued that patents in different kinds of industries – such as software patents – should be protected for different lengths of time.


title: Heuristic

text: Stereotyping is a type of heuristic that people use to form opinions or make judgements about things they have never seen or experienced. They work as a mental shortcut to assess everything from the social status of a person (based on their actions), to whether a plant is a tree based on the assumption that it is tall, has a trunk and has leaves (even though the person making the evaluation might never have seen that particular type of tree before).


title: Heuristic

text: Stereotypes, as first described by journalist Walter Lippmann in his book "Public Opinion" (1922), are the pictures we have in our heads that are built around experiences as well as what we are told about the world.


title: Heuristic

text: A heuristic can be used in artificial intelligence systems while searching a solution space. The heuristic is derived by using some function that is put into the system by the designer, or by adjusting the weight of branches based on how likely each branch is to lead to a goal node.


title: Diffie–Hellman key exchange

text: Diffie–Hellman key exchange is a mathematical method of securely exchanging cryptographic keys over a public channel and was one of the first public-key protocols as conceived by Ralph Merkle and named after Whitfield Diffie and Martin Hellman. DH is one of the earliest practical examples of public key exchange implemented within the field of cryptography. Published in 1976 by Diffie and Hellman, this is the earliest publicly known work that proposed the idea of a private key and a corresponding public key.


title: Diffie–Hellman key exchange

text: Traditionally, secure encrypted communication between two parties required that they first exchange keys by some secure physical means, such as paper key lists transported by a trusted courier. The Diffie–Hellman key exchange method allows two parties that have no prior knowledge of each other to jointly establish a shared secret key over an insecure channel. This key can then be used to encrypt subsequent communications using a symmetric-key cipher.


title: Diffie–Hellman key exchange

text: Diffie–Hellman is used to secure a variety of Internet services. However, research published in October 2015 suggests that the parameters in use for many DH Internet applications at that time are not strong enough to prevent compromise by very well-funded attackers, such as the security services of some countries.


title: Diffie–Hellman key exchange

text: The scheme was published by Whitfield Diffie and Martin Hellman in 1976, but in 1997 it was revealed that James H. Ellis, Clifford Cocks, and Malcolm J. Williamson of GCHQ, the British signals intelligence agency, had previously shown in 1969 how public-key cryptography could be achieved.


title: Diffie–Hellman key exchange

text: Although Diffie–Hellman key agreement itself is a non-authenticated key-agreement protocol, it provides the basis for a variety of authenticated protocols, and is used to provide forward secrecy in Transport Layer Security's ephemeral modes (referred to as EDH or DHE depending on the cipher suite).


title: Diffie–Hellman key exchange

text: The method was followed shortly afterwards by RSA, an implementation of public-key cryptography using asymmetric algorithms.


title: Diffie–Hellman key exchange

text: Expired from 1977 describes the now public-domain algorithm. It credits Hellman, Diffie, and Merkle as inventors.


title: Diffie–Hellman key exchange

text: In 2002, Hellman suggested the algorithm be called Diffie–Hellman–Merkle key exchange in recognition of Ralph Merkle's contribution to the invention of public-key cryptography (Hellman, 2002), writing:


title: Diffie–Hellman key exchange

text: Diffie–Hellman key exchange establishes a shared secret between two parties that can be used for secret communication for exchanging data over a public network. An analogy illustrates the concept of public key exchange by using colors instead of very large numbers:


title: Diffie–Hellman key exchange

text: The process begins by having the two parties, Alice and Bob, publicly agree on an arbitrary starting color that does not need to be kept secret. In this example, the color is yellow. Each person also selects a secret color that they keep to themselves – in this case, red and cyan. The crucial part of the process is that Alice and Bob each mix their own secret color together with their mutually shared color, resulting in orange-tan and light-blue mixtures respectively, and then publicly exchange the two mixed colors. Finally, each of them mixes the color they received from the partner with their own private color. The result is a final color mixture (yellow-brown in this case) that is identical to their partner's final color mixture.


title: Diffie–Hellman key exchange

text: If a third party listened to the exchange, they would only know the common color (yellow) and the first mixed colors (orange-tan and light-blue), but it would be very hard for them to find out the final secret color (yellow-brown). Bringing the analogy back to a real-life exchange using large numbers rather than colors, this determination is computationally expensive. It is impossible to compute in a practical amount of time even for modern supercomputers.


title: Diffie–Hellman key exchange

text: The simplest and the original implementation of the protocol uses the multiplicative group of integers modulo "p", where "p" is prime, and "g" is a primitive root modulo "p". These two values are chosen in this way to ensure that the resulting shared secret can take on any value from 1 to "p"–1. Here is an example of the protocol, with non-secret values in blue, and secret values in red.


title: Diffie–Hellman key exchange

text: Only "a" and "b" are kept secret. All the other values – "p", "g", "g" mod "p", and "g" mod "p" – are sent in the clear. The strength of the scheme comes from the fact that "g" mod "p" = "g" mod "p" take extremely long times to compute by any known algorithm just from the knowledge of "p", "g", "g" mod "p", and "g" mod "p". Once Alice and Bob compute the shared secret they can use it as an encryption key, known only to them, for sending messages across the same open communications channel.


title: Diffie–Hellman key exchange

text: Of course, much larger values of "a", "b", and "p" would be needed to make this example secure, since there are only 23 possible results of "n" mod 23. However, if "p" is a prime of at least 600 digits, then even the fastest modern computers using the fastest known algorithm cannot find "a" given only "g", "p" and "g" mod "p". Such a problem is called the discrete logarithm problem. The computation of "g" mod "p" is known as modular exponentiation and can be done efficiently even for large numbers.


title: Diffie–Hellman key exchange

text: The chart below depicts who knows what, again with non-secret values in blue, and secret values in red. Here Eve is an eavesdropper – she watches what is sent between Alice and Bob, but she does not alter the contents of their communications.


title: Diffie–Hellman key exchange

text: Now s is the shared secret key and it is known to both Alice and Bob, but "not" to Eve. Note that it is not helpful for Eve to compute "AB", which equals "g" mod p.


title: Diffie–Hellman key exchange

text: Note: It should be difficult for Alice to solve for Bob's private key or for Bob to solve for Alice's private key. If it is not difficult for Alice to solve for Bob's private key (or vice versa), Eve may simply substitute her own private / public key pair, plug Bob's public key into her private key, produce a fake shared secret key, and solve for Bob's private key (and use that to solve for the shared secret key. Eve may attempt to choose a public / private key pair that will make it easy for her to solve for Bob's private key).


title: Diffie–Hellman key exchange

text: Both Alice and Bob are now in possession of the group element "g = g", which can serve as the shared secret key. The group "G" satisfies the requisite condition for secure communication as long as there is no efficient algorithm for determining "g" given "g", "g", and "g".


title: Diffie–Hellman key exchange

text: For example, the elliptic curve Diffie–Hellman protocol is a variant that represents an element of G as a point on an elliptic curve instead of as an integer modulo n. Variants using hyperelliptic curves have also been proposed. The supersingular isogeny key exchange is a Diffie–Hellman variant that has been designed to be secure against quantum computers.


title: Diffie–Hellman key exchange

text: The used keys can either be ephemeral or static (long term) key, but could even be mixed, so called semi-static DH. These variants have different properties and hence different use cases. An overview over many variants and some also discussions can for example be found in NIST SP 800-56A. Here just a basic list:


title: Diffie–Hellman key exchange

text: It is possible to use ephemeral and static keys in one key agreement to provide more security as for example shown in NIST SP 800-56A, but it is also possible to combine those in a single DH key exchange, which is then called triple DH (3-DH).


title: Diffie–Hellman key exchange

text: In 1997 a kind of triple DH was proposed by Simon Blake-Wilson, Don Johnson, Alfred Menezes in "Key Agreement Protocols and their Security Analysis (1997)", which was improved by C. Kudla and K. G. Paterson in “Modular Security Proofs for Key Agreement Protocols (2005)” and shown to be secure. It's also used or mentioned in other variants. For example:


title: Diffie–Hellman key exchange

text: The long term secret keys of Alice and Bob are denoted by "a" and "b" respectively, with public keys "A" and "B", as well as the ephemeral key pairs "x, X" and "y, Y". Then protocol is:


title: Diffie–Hellman key exchange

text: The long term public keys need to be transferred somehow. That can be done beforehand in a separate, trusted channel, or the public keys can be encrypted using some partial key agreement to preserve anonymity. For more of such details as well as other improvements like side channel protection or explicit key confirmation, as well as early messages and additional password authentication, one could e.g. have a look at "Advanced modular handshake for key agreement and optional authentication"


title: Diffie–Hellman key exchange

text: Diffie–Hellman key agreement is not limited to negotiating a key shared by only two participants. Any number of users can take part in an agreement by performing iterations of the agreement protocol and exchanging intermediate data (which does not itself need to be kept secret). For example, Alice, Bob, and Carol could participate in a Diffie–Hellman agreement as follows, with all operations taken to be modulo "p":


title: Diffie–Hellman key exchange

text: An eavesdropper has been able to see " mod p", " mod p", " mod p", " mod p", " mod p", and " mod p", but cannot use any combination of these to efficiently reproduce " mod p".


title: Diffie–Hellman key exchange

text: These principles leave open various options for choosing in which order participants contribute to keys. The simplest and most obvious solution is to arrange the "N" participants in a circle and have "N" keys rotate around the circle, until eventually every key has been contributed to by all "N" participants (ending with its owner) and each participant has contributed to "N" keys (ending with their own). However, this requires that every participant perform "N" modular exponentiations.


title: Diffie–Hellman key exchange

text: By choosing a more optimal order, and relying on the fact that keys can be duplicated, it is possible to reduce the number of modular exponentiations performed by each participant to using a divide-and-conquer-style approach, given here for eight participants:


title: Diffie–Hellman key exchange

text: Once this operation has been completed all participants will possess the secret ", but each participant will have performed only four modular exponentiations, rather than the eight implied by a simple circular arrangement.


title: Diffie–Hellman key exchange

text: The protocol is considered secure against eavesdroppers if "G" and "g" are chosen properly. In particular, the order of the group G must be large, particularly if the same group is used for large amounts of traffic. The eavesdropper has to solve the Diffie–Hellman problem to obtain "g". This is currently considered difficult for groups whose order is large enough. An efficient algorithm to solve the discrete logarithm problem would make it easy to compute "a" or "b" and solve the Diffie–Hellman problem, making this and many other public key cryptosystems insecure. Fields of small characteristic may be less secure.


title: Diffie–Hellman key exchange

text: The order of "G" should have a large prime factor to prevent use of the Pohlig–Hellman algorithm to obtain "a" or "b". For this reason, a Sophie Germain prime "q" is sometimes used to calculate , called a safe prime, since the order of "G" is then only divisible by 2 and "q". "g" is then sometimes chosen to generate the order "q" subgroup of "G", rather than "G", so that the Legendre symbol of "g" never reveals the low order bit of "a". A protocol using such a choice is for example IKEv2.


title: Diffie–Hellman key exchange

text: "g" is often a small integer such as 2. Because of the random self-reducibility of the discrete logarithm problem a small "g" is equally secure as any other generator of the same group.


title: Diffie–Hellman key exchange

text: If Alice and Bob use random number generators whose outputs are not completely random and can be predicted to some extent, then it is much easier to eavesdrop.


title: Diffie–Hellman key exchange

text: In the original description, the Diffie–Hellman exchange by itself does not provide authentication of the communicating parties and is thus vulnerable to a man-in-the-middle attack. Mallory (an active attacker executing the man-in-the-middle attack) may establish two distinct key exchanges, one with Alice and the other with Bob, effectively masquerading as Alice to Bob, and vice versa, allowing her to decrypt, then re-encrypt, the messages passed between them. Note that Mallory must continue to be in the middle, actively decrypting and re-encrypting messages every time Alice and Bob communicate. If she is ever absent, her previous presence is then revealed to Alice and Bob. They will know that all of their private conversations had been intercepted and decoded by someone in the channel. In most cases it will not help them get Mallory's private key, even if she used the same key for both exchanges.


title: Diffie–Hellman key exchange

text: A method to authenticate the communicating parties to each other is generally needed to prevent this type of attack. Variants of Diffie–Hellman, such as STS protocol, may be used instead to avoid these types of attacks.


title: Diffie–Hellman key exchange

text: The number field sieve algorithm, which is generally the most effective in solving the discrete logarithm problem, consists of four computational steps. The first three steps only depend on the order of the group G, not on the specific number whose finite log is desired. It turns out that much Internet traffic uses one of a handful of groups that are of order 1024 bits or less. By precomputing the first three steps of the number field sieve for the most common groups, an attacker need only carry out the last step, which is much less computationally expensive than the first three steps, to obtain a specific logarithm. The Logjam attack used this vulnerability to compromise a variety of Internet services that allowed the use of groups whose order was a 512-bit prime number, so called export grade. The authors needed several thousand CPU cores for a week to precompute data for a single 512-bit prime. Once that was done, individual logarithms could be solved in about a minute using two 18-core Intel Xeon CPUs.


title: Diffie–Hellman key exchange

text: As estimated by the authors behind the Logjam attack, the much more difficult precomputation needed to solve the discrete log problem for a 1024-bit prime would cost on the order of $100 million, well within the budget of a large national intelligence agency such as the U.S. National Security Agency (NSA). The Logjam authors speculate that precomputation against widely reused 1024-bit DH primes is behind claims in leaked NSA documents that NSA is able to break much of current cryptography.


title: Diffie–Hellman key exchange

text: To avoid these vulnerabilities, the Logjam authors recommend use of elliptic curve cryptography, for which no similar attack is known. Failing that, they recommend that the order, "p", of the Diffie–Hellman group should be at least 2048 bits. They estimate that the pre-computation required for a 2048-bit prime is 10 times more difficult than for 1024-bit primes.


title: Diffie–Hellman key exchange

text: Public key encryption schemes based on the Diffie–Hellman key exchange have been proposed. The first such scheme is the ElGamal encryption. A more modern variant is the Integrated Encryption Scheme.


title: Diffie–Hellman key exchange

text: Protocols that achieve forward secrecy generate new key pairs for each session and discard them at the end of the session. The Diffie–Hellman key exchange is a frequent choice for such protocols, because of its fast key generation.


title: Diffie–Hellman key exchange

text: When Alice and Bob share a password, they may use a password-authenticated key agreement (PK) form of Diffie–Hellman to prevent man-in-the-middle attacks. One simple scheme is to compare the hash of s concatenated with the password calculated independently on both ends of channel. A feature of these schemes is that an attacker can only test one specific password on each iteration with the other party, and so the system provides good security with relatively weak passwords. This approach is described in ITU-T Recommendation X.1035, which is used by the G.hn home networking standard.


title: Diffie–Hellman key exchange

text: It is also possible to use Diffie–Hellman as part of a public key infrastructure, allowing Bob to encrypt a message so that only Alice will be able to decrypt it, with no prior communication between them other than Bob having trusted knowledge of Alice's public key. Alice's public key is formula_3. To send her a message, Bob chooses a random "b" and then sends Alice formula_4 (unencrypted) together with the message encrypted with symmetric key formula_5. Only Alice can determine the symmetric key and hence decrypt the message because only she has "a" (the private key). A pre-shared public key also prevents man-in-the-middle attacks.


title: Diffie–Hellman key exchange

text: In practice, Diffie–Hellman is not used in this way, with RSA being the dominant public key algorithm. This is largely for historical and commercial reasons, namely that RSA Security created a certificate authority for key signing that became Verisign. Diffie–Hellman, as elaborated above, cannot directly be used to sign certificates. However, the ElGamal and DSA signature algorithms are mathematically related to it, as well as MQV, STS and the IKE component of the IPsec protocol suite for securing Internet Protocol communications.


title: Constituent Assembly of India

text: The Constituent Assembly of India was elected to frame the Constitution of India. It was elected by the 'Provincial Assembly'. Following India's independence from the British rule in 1947, its members served as the nation's first Parliament as the 'Provisional Parliament of India'.


title: Constituent Assembly of India

text: The idea for a Constituent Assembly was proposed in Dec 1934 by M. N. Roy, a pioneer of the Communist movement in India and an advocate of radical democracy. It became an official demand of the Indian National Congress in 1935. The Indian National Congress held its session at Lucknow in April 1936 presided by Pt. Jawahar Lal Nehru. The official demand for Constituent Assembly was raised and Government of India Act, 1935 was rejected as it imposed the Constitution which was against the will of the Indians. C. Rajagopalachari voiced the demand for a Constituent Assembly on 15 November 1939 based on adult franchise, and was accepted by the British in August 1940.


title: Constituent Assembly of India

text: On 8 August 1940, a statement was made by Viceroy Lord Linlithgow about the expansion of the Governor-General's Executive Council and the establishment of a War Advisory Council. This offer, known as the August Offer, included giving full weight to minority opinions and allowing Indians to draft their own constitution. Under the Cabinet Mission Plan of 1946, elections were held for the first time for the Constituent Assembly. The Constitution of India was drafted by the Constituent Assembly, and it was implemented under the Cabinet Mission Plan on 16 May 1946. The members of the Constituent Assembly were elected by the provincial assemblies by a single, transferable-vote system of proportional representation. The total membership of the Constituent Assembly was 389 of which 292 were representatives of the provinces, 93 represented the princely states and four were from the chief commissioner provinces of Delhi, Ajmer-Merwara, Coorg and British Baluchistan.


title: Constituent Assembly of India

text: The elections for the 296 seats assigned to the British Indian provinces were completed by August 1946. Congress won 208 seats, and the Muslim League 73. After this election, the Muslim League refused to cooperate with the Congress and the political situation deteriorated. Hindu-Muslim riots began, and the Muslim League demanded a separate constituent assembly for Muslims in India. On 3 June 1947 Lord Mountbatten, the last British Governor-General of India, announced his intention to scrap the Cabinet Mission Plan; this culminated in the Indian Independence Act 1947 and the separate nations of India and Pakistan. The Indian Independence Act was passed on 18 July 1947 and, although it was earlier declared that India would become independent in June 1948, this event led to independence on 15 August 1947. The Constituent Assembly met for the first time on 9 December 1946, reassembling on 14 August 1947 as a sovereign body and successor to the British parliament's authority in India.


title: Constituent Assembly of India

text: As a result of the partition, under the Mountbatten plan, a separate Constituent Assembly of Pakistan was established on 3 June 1947. The representatives of the areas incorporated into Pakistan ceased to be members of the Constituent Assembly of India. New elections were held for the West Punjab and East Bengal (which became part of Pakistan, although East Bengal later seceded to become Bangladesh); the membership of the Constituent Assembly was 299 after the reorganization, and it met on 31 December 1947.


title: Constituent Assembly of India

text: The constitution was drafted by 299 delegates from different caste, region religion, gender etc. These delegates sat over 114 days spread over 3 years (2 years 11 months and 18 days to be precise) and discussed what the constitution should contain and what laws should be included. The Drafting Committee of the Constitution was chaired by B. R. Ambedkar.


title: Constituent Assembly of India

text: The Constituent Assembly of India, consisting of indirectly elected representatives, was established to draft a constitution for India (including the now-separate countries of Pakistan and Bangladesh). It existed for approx three years, the first parliament of India after independence in 1947. The Assembly was not elected based on universal adult suffrage, and Muslims and Sikhs received special representation as minorities. The Muslim League boycotted the Assembly after failing to prevent its creation. Although a large part of the Constituent Assembly was drawn from the Congress Party in a one-party environment, the Congress Party included a wide diversity of opinions—from conservative industrialists to radical Marxists, to Hindu revivalists.


title: Constituent Assembly of India

text: The Assembly met for the first time in New Delhi on 9 December 1946, and its last session was held on 24 January 1950. The hope of the Assembly was expressed by Jawaharlal Nehru:


title: Constituent Assembly of India

text: India was still under British rule when the Constituent Assembly was established, following negotiations between Indian leaders and members of the 1946 Cabinet Mission to India from the United Kingdom. Provincial assembly elections were held in early 1946. Constituent Assembly members were elected indirectly by members of the newly elected provincial assemblies, and initially included representatives for those provinces that formed part of Pakistan (some of which are now in Bangladesh). The Constituent Assembly had 389 representatives, including fifteen women.


title: Constituent Assembly of India

text: The Interim Government of India was formed on 2 September 1946 from the newly elected Constituent Assembly. The Congress Party held a large majority in the Assembly (69 percent of the seats), and the Muslim League held nearly all the seats reserved in the Assembly for Muslims. There were also members of smaller parties, such as the Scheduled Caste Federation, the Communist Party of India and the Unionist Party.


title: Constituent Assembly of India

text: In June 1947 delegations from Sindh, East Bengal, Baluchistan, West Punjab and the North West Frontier Province withdrew to form the Constituent Assembly of Pakistan, meeting in Karachi. On 15 August 1947 the Dominion of India and Dominion of Pakistan became independent nations, and members of the Constituent Assembly who had not withdrawn to Karachi became India's Parliament. Twenty-eight members of the Muslim League joined the Indian Assembly, and 93 members were later nominated from the princely states; the Congress Party secured a majority of 82 percent.


title: Constituent Assembly of India

text: At 11 AM on 9 December 1946, the Assembly began its first session, with 211 members attending. The Assembly approved the draft constitution on 26 November 1949. On 26 January 1950, the constitution took effect (commemorated as Republic Day), and the Constituent Assembly became the Provisional Parliament of India (continuing until after the first elections under the new constitution in 1952).


title: Constituent Assembly of India

text: Dr. Rajendra Prasad was elected as the president and Harendra Coomar Mookerjee, a Christian from Bengal and former vice-chancellor of Calcutta University, was vice-president. Mookerjee, additionally to chairing the assembly's Minorities Committee, was appointed governor of West Bengal after India became a republic. Jurist B. N. Rau was appointed constitutional adviser to the assembly; Rau prepared the original draft of the constitution and was later appointed a judge in the Permanent Court of International Justice in The Hague.


title: Constituent Assembly of India

text: The Constituent Assembly appointed a total of 22 committees to deal with different tasks of constitution-making. Out of these, Eight were major committees and the others were minor committees.


title: Constituent Assembly of India

text: The constitution has been, in more recent times, critiqued on the basis of the fact that the members of the Constituent Assembly were not truly chosen by universal suffrage, but rather were elected by provincial assemblies that themselves were not elected by universal suffrage. It has been argued that the Congress party did not seek to completely dismantle British power, but rather transfer its power into its own hands.


title: Constituent Assembly of India

text: In his book "The Constitution of India: Miracle, Surrender, Hope," Rajeev Dhavan has argued that the Indian people did not have much say in the making of the Constitution which was they had no choice but to accept.


title: Quicksort

text: Quicksort is an efficient, general-purpose sorting algorithm. Quicksort was developed by British computer scientist Tony Hoare in 1959 and published in 1961, it is still a commonly used algorithm for sorting. Overall, it is slightly faster than merge sort and heapsort for randomized data, particularly on larger distributions.


title: Quicksort

text: Quicksort is a divide-and-conquer algorithm. It works by selecting a 'pivot' element from the array and partitioning the other elements into two sub-arrays, according to whether they are less than or greater than the pivot. For this reason, it is sometimes called partition-exchange sort. The sub-arrays are then sorted recursively. This can be done in-place, requiring small additional amounts of memory to perform the sorting.


title: Quicksort

text: Quicksort is a comparison sort, meaning that it can sort items of any type for which a "less-than" relation (formally, a total order) is defined. Most implementations of quicksort are not stable, meaning that the relative order of equal sort items is not preserved.


title: Quicksort

text: Mathematical analysis of quicksort shows that, on average, the algorithm takes formula_1 comparisons to sort "n" items. In the worst case, it makes formula_2 comparisons.


title: Quicksort

text: The quicksort algorithm was developed in 1959 by Tony Hoare while he was a visiting student at Moscow State University. At that time, Hoare was working on a machine translation project for the National Physical Laboratory. As a part of the translation process, he needed to sort the words in Russian sentences before looking them up in a Russian-English dictionary, which was in alphabetical order on magnetic tape. After recognizing that his first idea, insertion sort, would be slow, he came up with a new idea. He wrote the partition part in Mercury Autocode but had trouble dealing with the list of unsorted segments. On return to England, he was asked to write code for Shellsort. Hoare mentioned to his boss that he knew of a faster algorithm and his boss bet sixpence that he did not. His boss ultimately accepted that he had lost the bet. Later, Hoare learned about ALGOL and its ability to do recursion that enabled him to publish the code in "Communications of the Association for Computing Machinery", the premier computer science journal of the time.


title: Quicksort

text: Quicksort gained widespread adoption, appearing, for example, in Unix as the default library sort subroutine. Hence, it lent its name to the C standard library subroutine and in the reference implementation of Java.


title: Quicksort

text: Robert Sedgewick's PhD thesis in 1975 is considered a milestone in the study of Quicksort where he resolved many open problems related to the analysis of various pivot selection schemes including Samplesort, adaptive partitioning by Van Emden as well as derivation of expected number of comparisons and swaps. Jon Bentley and Doug McIlroy in 1993 incorporated various improvements for use in programming libraries, including a technique to deal with equal elements and a pivot scheme known as "pseudomedian of nine," where a sample of nine elements is divided into groups of three and then the median of the three medians from three groups is chosen. Bentley described another simpler and compact partitioning scheme in his book "Programming Pearls" that he attributed to Nico Lomuto. Later Bentley wrote that he used Hoare's version for years but never really understood it but Lomuto's version was simple enough to prove correct. Bentley described Quicksort as the "most beautiful code I had ever written" in the same essay. Lomuto's partition scheme was also popularized by the textbook "Introduction to Algorithms" although it is inferior to Hoare's scheme because it does three times more swaps on average and degrades to runtime when all elements are equal. McIlroy would further produce an"AntiQuicksort" () function in 1998, which consistently drives even his 1993 variant of Quicksort into quadratic behavior by producing adversarial data on-the-fly.


title: Quicksort

text: Quicksort is a type of divide and conquer algorithm for sorting an array, based on a partitioning routine; the details of this partitioning can vary somewhat, so that quicksort is really a family of closely related algorithms. Applied to a range of at least two elements, partitioning produces a division into two consecutive non empty sub-ranges, in such a way that no element of the first sub-range is greater than any element of the second sub-range. After applying this partition, quicksort then recursively sorts the sub-ranges, possibly after excluding from them an element at the point of division that is at this point known to be already in its final location. Due to its recursive nature, quicksort (like the partition routine) has to be formulated so as to be callable for a range within a larger array, even if the ultimate goal is to sort a complete array. The steps for in-place quicksort are:


title: Quicksort

text: The choice of partition routine (including the pivot selection) and other details not entirely specified above can affect the algorithm's performance, possibly to a great extent for specific input arrays. In discussing the efficiency of quicksort, it is therefore necessary to specify these choices first. Here we mention two specific partition methods.


title: Quicksort

text: This scheme is attributed to Nico Lomuto and popularized by Bentley in his book "Programming Pearls" and Cormen "et al." in their book "Introduction to Algorithms". In most formulations this scheme chooses as the pivot the last element in the array. The algorithm maintains index as it scans the array using another index such that the elements at through (inclusive) are less than the pivot, and the elements at through (inclusive) are equal to or greater than the pivot. As this scheme is more compact and easy to understand, it is frequently used in introductory material, although it is less efficient than Hoare's original scheme e.g., when all elements are equal. The complexity of Quicksort with this scheme degrades to when the array is already in order, due to the partition being the worst possible one. There have been various variants proposed to boost performance including various ways to select the pivot, deal with equal elements, use other sorting algorithms such as insertion sort for small arrays, and so on. In pseudocode, a quicksort that sorts elements at through (inclusive) of an array can be expressed as:


title: Quicksort

text: The original partition scheme described by Tony Hoare uses two pointers (indices into the range) that start at both ends of the array being partitioned, then move toward each other, until they detect an inversion: a pair of elements, one greater than the bound (Hoare's terms for the pivot value) at the first pointer, and one less than the bound at the second pointer; if at this point the first pointer is still before the second, these elements are in the wrong order relative to each other, and they are then exchanged. After this the pointers are moved inwards, and the search for an inversion is repeated; when eventually the pointers cross (the first points after the second), no exchange is performed; a valid partition is found, with the point of division between the crossed pointers (any entries that might be strictly between the crossed pointers are equal to the pivot and can be excluded from both sub-ranges formed). With this formulation it is possible that one sub-range turns out to be the whole original range, which would prevent the algorithm from advancing. Hoare therefore stipulates that at the end, the sub-range containing the pivot element (which still is at its original position) can be decreased in size by excluding that pivot, after (if necessary) exchanging it with the sub-range element closest to the separation; thus, termination of quicksort is ensured.


title: Quicksort

text: With respect to this original description, implementations often make minor but important variations. Notably, the scheme as presented below includes elements equal to the pivot among the candidates for an inversion (so "greater than or equal" and "less than or equal" tests are used instead of "greater than" and "less than" respectively; since the formulation uses which is actually reflected by the use of strict comparison operators). While there is no reason to exchange elements equal to the bound, this change allows tests on the pointers themselves to be omitted, which are otherwise needed to ensure they do not run out of range. Indeed, since at least one instance of the pivot value is present in the range, the first advancement of either pointer cannot pass across this instance if an inclusive test is used; once an exchange is performed, these exchanged elements are now both strictly ahead of the pointer that found them, preventing that pointer from running off. (The latter is true independently of the test used, so it would be possible to use the inclusive test only when looking for the first inversion. However, using an inclusive test throughout also ensures that a division near the middle is found when all elements in the range are equal, which gives an important efficiency gain for sorting arrays with many equal elements.) The risk of producing a non-advancing separation is avoided in a different manner than described by Hoare. Such a separation can only result when no inversions are found, with both pointers advancing to the pivot element at the first iteration (they are then considered to have crossed, and no exchange takes place). The division returned is after the final position of the second pointer, so the case to avoid is where the pivot is the final element of the range and all others are smaller than it. Therefore, the pivot choice must avoid the final element (in Hoare's description it could be any element in the range); this is done here by rounding "down" the middle position, using the floor function. This illustrates that the argument for correctness of an implementation of the Hoare partition scheme can be subtle, and it is easy to get it wrong.


title: Quicksort

text: Hoare's scheme is more efficient than Lomuto's partition scheme because it does three times fewer swaps on average. Also, as mentioned, the implementation given creates a balanced partition even when all values are equal., which Lomuto's scheme does not. Like Lomuto's partition scheme, Hoare's partitioning also would cause Quicksort to degrade to for already sorted input, if the pivot was chosen as the first or the last element. With the middle element as the pivot, however, sorted data results with (almost) no swaps in equally sized partitions leading to best case behavior of Quicksort, i.e. . Like others, Hoare's partitioning doesn't produce a stable sort. In this scheme, the pivot's final location is not necessarily at the index that is returned, as the pivot and elements equal to the pivot can end up anywhere within the partition after a partition step, and may not be sorted until the base case of a partition with a single element is reached via recursion. The next two segments that the main algorithm recurs on are (elements ≤ pivot) and (elements ≥ pivot) as opposed to and as in Lomuto's scheme.


title: Quicksort

text: Let's expand a little bit on the next two segments that the main algorithm recurs on. Because we are using strict comparators (>, <) in the ' loops to prevent ourselves from running out of range, there's a chance that the pivot itself gets swapped with other elements in the partition function. Therefore, the index returned in the partition function isn't necessarily where the actual pivot is. Consider the example of ', following the scheme, after the first partition the array becomes , the "index" returned is 2, which is the number 1, when the real pivot, the one we chose to start the partition with was the number 3. With this example, we see how it is necessary to include the returned index of the partition function in our subsequent recursions. As a result, we are presented with the choices of either recursing on and , or and . Which of the two options we choose depends on which index (i or j) we return in the partition function when the indices cross, and how we choose our pivot in the partition function (floor v.s. ceiling).


title: Quicksort

text: Let's first examine the choice of recursing on and , with the example of sorting an array where multiple identical elements exist '. If index i (the "latter" index) is returned after indices cross in the partition function, the index 1 would be returned after the first partition. The subsequent recursion on would be on (0, 1), which corresponds to the exact same array '. A non-advancing separation that causes infinite recursion is produced. It is therefore obvious that when recursing on and , because the left half of the recursion includes the returned index, it is the partition function's job to exclude the "tail" in non-advancing scenarios. Which is to say, index j (the "former" index when indices cross) should be returned instead of i. Going with a similar logic, when considering the example of an already sorted array ', the choice of pivot needs to be "floor" to ensure that the pointers stop on the "former" instead of the "latter" (with "ceiling" as the pivot, the index 1 would be returned and included in ' causing infinite recursion). It is for the exact same reason why choice of the last element as pivot must be avoided.


title: Quicksort

text: The choice of recursing on and follows the exact same logic as above. Because the right half of the recursion includes the returned index, it is the partition function's job to exclude the "head" in non-advancing scenarios. The index i (the "latter" index after the indices cross) in the partition function needs to be returned, and "ceiling" needs to be chosen as the pivot. The two nuances are clear, again, when considering the examples of sorting an array where multiple identical elements exist ('), and an already sorted array ' respectively. It is noteworthy that with version of recursion, for the same reason, choice of the first element as pivot must be avoided.


title: Quicksort

text: In the very early versions of quicksort, the leftmost element of the partition would often be chosen as the pivot element. Unfortunately, this causes worst-case behavior on already sorted arrays, which is a rather common use-case. The problem was easily solved by choosing either a random index for the pivot, choosing the middle index of the partition or (especially for longer partitions) choosing the median of the first, middle and last element of the partition for the pivot (as recommended by Sedgewick). This "median-of-three" rule counters the case of sorted (or reverse-sorted) input, and gives a better estimate of the optimal pivot (the true median) than selecting any single element, when no information about the ordering of the input is known.


title: Quicksort

text: It puts a median into codice_1 first, then that new value of codice_1 is used for a pivot, as in a basic algorithm presented above.


title: Quicksort

text: Specifically, the expected number of comparisons needed to sort elements (see ) with random pivot selection is . Median-of-three pivoting brings this down to , at the expense of a three-percent increase in the expected number of swaps. An even stronger pivoting rule, for larger arrays, is to pick the ninther, a recursive median-of-three (Mo3), defined as


title: Quicksort

text: Selecting a pivot element is also complicated by the existence of integer overflow. If the boundary indices of the subarray being sorted are sufficiently large, the naïve expression for the middle index, , will cause overflow and provide an invalid pivot index. This can be overcome by using, for example, to index the middle element, at the cost of more complex arithmetic. Similar issues arise in some other methods of selecting the pivot element.


title: Quicksort

text: With a partitioning algorithm such as the Lomuto partition scheme described above (even one that chooses good pivot values), quicksort exhibits poor performance for inputs that contain many repeated elements. The problem is clearly apparent when all the input elements are equal: at each recursion, the left partition is empty (no input values are less than the pivot), and the right partition has only decreased by one element (the pivot is removed). Consequently, the Lomuto partition scheme takes quadratic time to sort an array of equal values. However, with a partitioning algorithm such as the Hoare partition scheme, repeated elements generally results in better partitioning, and although needless swaps of elements equal to the pivot may occur, the running time generally decreases as the number of repeated elements increases (with memory cache reducing the swap overhead). In the case where all elements are equal, Hoare partition scheme needlessly swaps elements, but the partitioning itself is best case, as noted in the Hoare partition section above.


title: Quicksort

text: To solve the Lomuto partition scheme problem (sometimes called the Dutch national flag problem), an alternative linear-time partition routine can be used that separates the values into three groups: values less than the pivot, values equal to the pivot, and values greater than the pivot. (Bentley and McIlroy call this a "fat partition" and it was already implemented in the of Version 7 Unix.) The values equal to the pivot are already sorted, so only the less-than and greater-than partitions need to be recursively sorted. In pseudocode, the quicksort algorithm becomes


title: Quicksort

text: The codice_3 algorithm returns indices to the first ('leftmost') and to the last ('rightmost') item of the middle partition. Every item of the partition is equal to codice_4 and is therefore sorted. Consequently, the items of the partition need not be included in the recursive calls to codice_5.


title: Quicksort

text: The best case for the algorithm now occurs when all elements are equal (or are chosen from a small set of elements). In the case of all equal elements, the modified quicksort will perform only two recursive calls on empty subarrays and thus finish in linear time (assuming the codice_3 subroutine takes no longer than linear time).


title: Quicksort

text: Quicksort's divide-and-conquer formulation makes it amenable to parallelization using task parallelism. The partitioning step is accomplished through the use of a parallel prefix sum algorithm to compute an index for each array element in its section of the partitioned array. Given an array of size , the partitioning step performs work in time and requires additional scratch space. After the array has been partitioned, the two partitions can be sorted recursively in parallel. Assuming an ideal choice of pivots, parallel quicksort sorts an array of size in work in time using additional space.


title: Quicksort

text: Quicksort has some disadvantages when compared to alternative sorting algorithms, like merge sort, which complicate its efficient parallelization. The depth of quicksort's divide-and-conquer tree directly impacts the algorithm's scalability, and this depth is highly dependent on the algorithm's choice of pivot. Additionally, it is difficult to parallelize the partitioning step efficiently in-place. The use of scratch space simplifies the partitioning step, but increases the algorithm's memory footprint and constant overheads.


title: Quicksort

text: Other more sophisticated parallel sorting algorithms can achieve even better time bounds. For example, in 1991 David Powers described a parallelized quicksort (and a related radix sort) that can operate in time on a CRCW (concurrent read and concurrent write) PRAM (parallel random-access machine) with processors by performing partitioning implicitly.


title: Quicksort

text: The most unbalanced partition occurs when one of the sublists returned by the partitioning routine is of size . This may occur if the pivot happens to be the smallest or largest element in the list, or in some implementations (e.g., the Lomuto partition scheme as described above) when all the elements are equal.


title: Quicksort

text: If this happens repeatedly in every partition, then each recursive call processes a list of size one less than the previous list. Consequently, we can make nested calls before we reach a list of size 1. This means that the call tree is a linear chain of nested calls. The th call does work to do the partition, and formula_3, so in that case quicksort takes time.


title: Quicksort

text: In the most balanced case, each time we perform a partition we divide the list into two nearly equal pieces. This means each recursive call processes a list of half the size. Consequently, we can make only nested calls before we reach a list of size 1. This means that the depth of the call tree is . But no two calls at the same level of the call tree process the same part of the original list; thus, each level of calls needs only time all together (each call has some constant overhead, but since there are only calls at each level, this is subsumed in the factor). The result is that the algorithm uses only time.


title: Quicksort

text: To sort an array of distinct elements, quicksort takes time in expectation, averaged over all permutations of elements with equal probability. Alternatively, if the algorithm selects the pivot uniformly at random from the input array, the same analysis can be used to bound the expected running time for any input sequence; the expectation is then take over the random choices made by the algorithm (Cormen "et al.", "Introduction to Algorithms", Section 7.3).


title: Quicksort

text: We list here three common proofs to this claim providing different insights into quicksort's workings.


title: Quicksort

text: If each pivot has rank somewhere in the middle 50 percent, that is, between the 25th percentile and the 75th percentile, then it splits the elements with at least 25% and at most 75% on each side. If we could consistently choose such pivots, we would only have to split the list at most formula_4 times before reaching lists of size 1, yielding an algorithm.


title: Quicksort

text: When the input is a random permutation, the pivot has a random rank, and so it is not guaranteed to be in the middle 50 percent. However, when we start from a random permutation, in each recursive call the pivot has a random rank in its list, and so it is in the middle 50 percent about half the time. That is good enough. Imagine that a coin is flipped: heads means that the rank of the pivot is in the middle 50 percent, tail means that it isn't. Now imagine that the coin is flipped over and over until it gets heads. Although this could take a long time, on average only flips are required, and the chance that the coin won't get heads after flips is highly improbable (this can be made rigorous using Chernoff bounds). By the same argument, Quicksort's recursion will terminate on average at a call depth of only formula_5. But if its average call depth is , and each level of the call tree processes at most elements, the total amount of work done on average is the product, . The algorithm does not have to verify that the pivot is in the middle half—if we hit it any constant fraction of the times, that is enough for the desired complexity.


title: Quicksort

text: An alternative approach is to set up a recurrence relation for the factor, the time needed to sort a list of size . In the most unbalanced case, a single quicksort call involves work plus two recursive calls on lists of size and , so the recurrence relation is


title: Quicksort

text: In the most balanced case, a single quicksort call involves work plus two recursive calls on lists of size , so the recurrence relation is


title: Quicksort

text: The outline of a formal proof of the expected time complexity follows. Assume that there are no duplicates as duplicates could be handled with linear time pre- and post-processing, or considered cases easier than the analyzed. When the input is a random permutation, the rank of the pivot is uniform random from 0 to . Then the resulting parts of the partition have sizes and , and i is uniform random from 0 to . So, averaging over all possible splits and noting that the number of comparisons for the partition is , the average number of comparisons over all permutations of the input sequence can be estimated accurately by solving the recurrence relation:


title: Quicksort

text: This means that, on average, quicksort performs only about 39% worse than in its best case. In this sense, it is closer to the best case than the worst case. A comparison sort cannot use less than comparisons on average to sort items (as explained in the article Comparison sort) and in case of large , Stirling's approximation yields , so quicksort is not much worse than an ideal comparison sort. This fast average runtime is another reason for quicksort's practical dominance over other sorting algorithms.


title: Quicksort

text: The following binary search tree (BST) corresponds to each execution of quicksort: the initial pivot is the root node; the pivot of the left half is the root of the left subtree, the pivot of the right half is the root of the right subtree, and so on. The number of comparisons of the execution of quicksort equals the number of comparisons during the construction of the BST by a sequence of insertions. So, the average number of comparisons for randomized quicksort equals the average cost of constructing a BST when the values inserted formula_13 form a random permutation.


title: Quicksort

text: Consider a BST created by insertion of a sequence formula_13 of values forming a random permutation. Let denote the cost of creation of the BST. We have formula_15 is a binary random variable expressing whether during the insertion of formula_16 there was a comparison to formula_17.


title: Quicksort

text: By linearity of expectation, the expected value formula_18 of is formula_19, once sorted, define intervals. The core structural observation is that formula_16 is compared to formula_17 in the algorithm if and only if formula_16 falls inside one of the two intervals adjacent to formula_17.


title: Quicksort

text: Observe that since formula_13 is a random permutation, formula_25 is also a random permutation, so the probability that formula_16 is adjacent to formula_17 is exactly formula_28.


title: Metalcore

text: Metalcore (also known as metallic hardcore) is a that combines elements of extreme metal and hardcore punk. As with other styles blending metal and hardcore, such as crust punk and grindcore, metalcore is noted for its use of breakdowns, slow, intense passages conducive to moshing. Other defining instrumental qualities include heavy riffs and stop-start rhythm guitar playing, occasional blast beats, and double bass drumming. Vocalists in the genre typically use thrash or scream vocals. Some later metalcore bands combine this with clean singing, often during the chorus. Death growls and gang vocals are common. 1990s metalcore bands were inspired by hardcore while later metalcore bands were inspired by melodic death metal bands like At the Gates and In Flames.


title: Metalcore

text: The roots of metalcore are in the 1980s when bands would combine hardcore punk with heavy metal. This included New York hardcore bands like Agnostic Front, Cro-Mags, and Killing Time, British hardcore punk bands like the Exploited and Discharge, and American crossover thrash bands like Dirty Rotten Imbeciles and Suicidal Tendencies. The genre emerged in the early 1990s and expanded in the mid–late 1990s. Metalcore bands like Integrity, Earth Crisis, Hatebreed, Converge, Shai Hulud, Vision of Disorder, Merauder, and Disembodied emerged and acquired underground success in the 1990s.


title: Metalcore

text: In the mid-2000s, metalcore became one of the most popular heavy metal subgenres with the success of bands like Bleeding Through, Avenged Sevenfold, Killswitch Engage, Hatebreed, Atreyu, Shadows Fall, As I Lay Dying, Unearth, Trivium, Bullet for My Valentine, and All That Remains. Metalcore's popularity continued in the 2010s with the success of bands like Asking Alexandria, August Burns Red, and the Devil Wears Prada. Metalcore subgenres like deathcore, easycore and electronicore also emerged in the 2000s decade. Other subgenres of metalcore include mathcore, nu metalcore, melodic metalcore and progressive metalcore.


title: Metalcore

text: Metalcore is known for its use of breakdowns, in which it was preceded by beatdown hardcore. Metalcore singers typically perform screaming, a vocal technique developed in the 1980s and characteristic of 1990s metalcore. Later metalcore bands often combine this with the use of standard singing, usually during the bridge or chorus of a song. The death growl technique is also popular.


title: Metalcore

text: The instrumentation of metalcore includes heavy guitar riffs often utilizing percussive pedal tones, stop-start rhythm guitar, double bass drumming, and breakdowns. Drop guitar tunings are often used. Most bands use tuning ranging between Drop D and A, although lower tunings, as well as 7 and 8 string guitars, are not uncommon. Drummers typically use a lot of double bass technique and general drumming styles across the board. Blast beats are also heard at times. According to author James Giordano, "tempos in metalcore tend to be slower than those found in thrash metal". Many later metalcore bands would include guitar solos in songs.


title: Metalcore

text: 1990s metalcore bands generally had a strong influence from heavy hardcore. In the 2000s, metalcore bands began to be exclusively inspired by heavy metal. Many 2000s metalcore bands were heavily inspired by melodic death metal and used strong elements of melodic death metal in their music. Malcolm Dome of "Revolver" wrote that without melodic death metal band At the Gates' 1995 album "Slaughter of the Soul", "modern American metalcore (everyone from As I Lay Dying and Killswitch Engage to All That Remains and the Black Dahlia Murder) wouldn't even exist." Graham Hartmann of "Loudwire" wrote "Although metalcore broke in the early 2000s, listening to At the Gates' 1995 album feels like a Nostradamus-esque prediction of how metal would evolve."


title: Metalcore

text: Black Flag and Bad Brains, among the originators of hardcore punk, admired and emulated Black Sabbath. British hardcore punk groups such as Discharge and the Exploited also took inspiration from heavy metal. The Misfits put out the "Earth A.D." album, becoming a crucial influence on thrash metal. Nonetheless, punk and metal cultures and music remained fairly separate through the first half of the 1980s. Cross-pollination between metal and hardcore eventually birthed the crossover thrash scene, which gestated at a Berkeley club called Ruthie's, in 1984. The term "metalcore" was originally used to refer to these crossover groups. Hardcore punk groups Corrosion of Conformity, D.R.I. and Suicidal Tendencies played alongside thrash metal groups like Metallica and Slayer. This scene influenced the skinhead wing of New York hardcore, which also began in 1984, and included groups such as Cro-Mags, Murphy's Law, Agnostic Front and Warzone. The Cro-Mags were among the most influential of these bands, drawing equally from Bad Brains, Motörhead and Black Sabbath. Cro-Mags also embraced some aspects of straight edge and Krishna consciousness. Another New York metal-influenced straight edge group of this time period is the Crumbsuckers. The year 1985 saw the development of the hardcore breakdown, an amalgamation of Bad Brains' reggae and metal backgrounds, which encouraged moshing. Agnostic Front's 1986 album "Cause for Alarm" showed a combination of hardcore punk with heavy metal influences.


title: Metalcore

text: Between 1993 and 1995, a wave of metallic hardcore bands emerged, including Integrity, Earth Crisis, Converge, Focal Point, Strongarm, Shai Hulud, Judge, Strife, Rorschach, Vision of Disorder Hatebreed, Zao, and Disembodied.


title: Metalcore

text: Integrity drew influence from the hardcore band G.I.S.M. and the thrash metal band Slayer, with others like Septic Death, Samhain, Motörhead and Joy Division. Earth Crisis and Hatebreed borrowed from hardcore punk and took influence from death metal. Earth Crisis's albums "Firestorm", "Destroy the Machines" and "Gomorrah's Season Ends" were early examples of metalcore, as was Vision of Disorder's self-titled full-length debut in 1996. Coalesce and Overcast were also important early metalcore groups. Journalist Lars Gotrich wrote, "Along with key records by The Dillinger Escape Plan and Botch, "Give Them Rope" (1997) is an underground milestone that helped [further] what was soon [universally] called 'metalcore'. At the risk of sounding too reductive—metalcore was the natural progression where extreme metal and hardcore met, but with spiraling time signatures that somehow felt more aggressive." Shai Hulud's 1997 album "Hearts Once Nourished with Hope and Compassion" became especially influential in the latter part of the decade. Hatebreed released their debut album "Satisfaction is the Death of Desire" in 1997. The album helped the band achieve underground success, selling 158,000 copies, according to Nielsen SoundScan.


title: Metalcore

text: In the early 2000s, metalcore started to gain more prominence, with several independent metal labels, including Century Media, Metal Blade and Roadrunner Records, signing metalcore bands. Hatebreed released their second album "Perseverance" in 2002. The album sold 234,000 copies in the United States. Hatebreed's 2003 album "The Rise of Brutality" and 2006 album "Supremacy" peaked at numbers 30 and 31 on the "Billboard" 200, respectively. A new subgenre, melodic metalcore, strongly influenced by Swedish melodic death metal, has formed and quickly came to the forefront of metalcore's rise to popularity. In 2002, Killswitch Engage's "Alive or Just Breathing" reached number 37 on the Heatseekers Albums chart. In 2004, Killswitch Engage's "The End of Heartache", Shadows Fall's "The War Within", and Atreyu's "The Curse" peaked at numbers 21, 20, and 36 on the "Billboard" 200, respectively. Also, in 2006, Atreyu's third studio album, "A Death-Grip On Yesterday" peaked at number 9 on the Billboard 200, only to be followed up by 2007's "Lead Sails Paper Anchor", which peaked at number 8. Atreyu's 2002 debut album "Suicide Notes and Butterfly Kisses", as of July 3, 2004, has sold 107,000 copies in the United States. Killswitch Engage's 2004 album "The End of Heartache" and 2006 album "As Daylight Dies" were both certified gold by the Recording Industry Association of America (RIAA) in 2007 and 2009, respectively. Killswitch Engage's 2002 album "Alive or Just Breathing", as of July 3, 2004, has sold 114,000 copies in the United States. Unearth began to have success among heavy metal fans in 2004 with the release of their second album "The Oncoming Storm", which peaked at number 1 on the Heatseekers Albums chart on July 17, 2004. On that same day, the album peaked at number 105 on the "Billboard" 200. Unearth's 2006 album "" peaked at number 35 on the "Billboard" 200. The band's 2008 album "The March" peaked at number 45 on the "Billboard" 200. "Oncoming Storm", "III: In the Eyes of Fire"', and "The March" peaked at numbers 6, 2 and 3 on the Independent Albums chart, respectively. Avenged Sevenfold's first two albums "Sounding the Seventh Trumpet" (2001) and "Waking the Fallen" (2003) were both metalcore albums. On the band's 2005 album "City of Evil", Avenged Sevenfold moved away from metalcore and changed to a traditional heavy metal sound. On June 15, 2005, Blabbermouth.net reported that "Waking the Fallen" has sold 172,253 copies in the United States, according to Nielsen SoundScan. On July 17, 2009, "Waking the Fallen" was certified gold by the RIAA.


title: Metalcore

text: Metalcore band As I Lay Dying also achieved success among heavy metal fans. The band's 2005 album "Shadows Are Security" peaked at number 35 on the "Billboard" 200 and sold 263,000 copies, according to Nielsen SoundScan. As I Lay Dying's 2007 album "An Ocean Between Us" peaked at number 8 on the "Billboard" 200 in 2007. As of April 2005, As I Lay Dying's 2003 album "Frail Words Collapse" sold 118,000 copies in the United States. All That Remains achieved success with their 2006 album "The Fall of Ideals", which, as of October 1, 2008, sold 175,000 copies in the United States. All That Remains' 2008 album "Overcome" peaked at number 16 on the "Billboard" 200. "Overcome" song "Two Weeks" peaked at number 9 on the Mainstream Rock Songs chart on May 16, 2009. Bullet for My Valentine's debut album "The Poison" was released in October 2005 in Europe and was released in February 2006 in the United States. On July 26, 2006, Blabbermouth.net reported that "The Poison" has sold 72,000 copies in the United States. On October 27, 2007, Blabbermouth.net reported that "The Poison" has sold 336,000 copies in the United States. On April 3, 2010, "Billboard" reported that "The Poison" sold 573,000 copies in the United States. "The Poison" was certified gold by the RIAA on January 30, 2009. Bullet for My Valentine's second album "Scream Aim Fire", released in 2008, peaked at number 4 on the "Billboard" 200 and sold 360,000 copies in the United States. Bullet for My Valentine's 2010 album "Fever" peaked at number 3 on the "Billboard" 200, selling 71,000 copies in the United States during its first week of release. "Fever" song "Your Betrayal" peaked at number 25 on the Bubbling Under Hot 100 chart. Trivium also achieved success among heavy metal fans when their 2005 album "Ascendancy" peaked at number 151 on the "Billboard" 200. Their albums "The Crusade" (2006) and "Shogun" (2008) peaked at numbers 25 and 23 on the "Billboard" 200, respectively. Bleeding Through's 2006 album "The Truth" peaked at number 1 on the Independent Albums chart on January 28, 2006. On that same day, the album peaked at number 48 on the "Billboard" 200.


title: Metalcore

text: In 2006 and 2007 a wave of metalcore bands strongly influenced by death metal dubbed deathcore gained moderate popularity. Notable bands that brought the genre to the fore include Bring Me the Horizon and Suicide Silence. Suicide Silence's "No Time to Bleed" peaked at number 32 on the "Billboard" 200, number 12 on the Rock Albums Chart and number 6 on the Hard Rock Albums Chart, while their album "The Black Crown" peaked at number 28 on the "Billboard" 200, number 7 on the Rock Albums Chart and number 3 on the Hard Rock Albums Chart. After its release, Whitechapel's album "This Is Exile" sold 5,900 in copies, which made it enter the "Billboard" 200 chart at position 118. Their self-titled album peaked at number 65 on the Canadian Albums Chart and also at number 47 on the "Billboard" 200. Their third album "A New Era of Corruption" sold about 10,600 copies in the United States in its first week of being released and peaked at position number 43 on the "Billboard" 200 chart. Furthermore, Bring Me the Horizon won the 2006 Kerrang! Awards for Best British Newcomer after they released their 2006 debut record "Count Your Blessings". However, Bring Me the Horizon abandoned the deathcore genre after the release of this album. San Diego natives Carnifex, witnessed success with their first album "Dead in My Arms", selling 5,000 copies with little publicity. On top of their non-stop touring and methodical songwriting resulted in Carnifex quickly getting signed to label Victory Records. Lastly, Australian deathcore band Thy Art Is Murder debuted at number 35 on the ARIA Charts with their album "Hate" (2012) making them the first extreme metal band to ever reach the Top 40 of this chart.


title: Metalcore

text: By the early 2010s, metalcore was evolving to more frequently incorporate synthesizers and elements from genres beyond rock and metal. Many other metalcore bands emerged and achieved a lot of success. The Devil Wears Prada's 2011 album "Dead Throne" (which sold 32,400 in its first week) reached number 10 on the "Billboard" 200 chart. Asking Alexandria also achieved success, with their 2009 signature song "Final Episode (Let's Change the Channel)" being certified gold by the RIAA. The band's 2011 album "Reckless & Relentless" peaked at number 9 on the "Billboard" 200. Other metalcore bands achieving success in the early and mid-2010s include Motionless in White, Blessthefall, The Amity Affliction, and August Burns Red.


title: Metalcore

text: In 2018, an article in Kerrang! referred to a revival of an earlier style of metalcore, described as "a dark, powerful combination of hardcore’s honest fury and thrash’s cutthroat riffage", citing Vein, Vatican, Thirty Nights of Violence, and Chamber as the frontrunners of the style. The Odyssey also referred to Code Orange, Knocked Loose, Varials, Jesus Piece, Counterparts, Employed to Serve and Kublai Khan as groups gaining significant success within the genre. Knocked Loose released their 2019 sophomore effort "A Different Shade of Blue" to critical and commercial success. Code Orange also saw critical acclaim and success with their Roadrunner Records debut "Forever" in 2017. Forever's title track was also nominated Grammy for Best Metal Performance in 2018.


title: Metalcore

text: In the early-2020s, a number of bands gained prominence in the scene that revived the sound of groups from the mid-to-late-2000s, fronted by Static Dress, SeeYouSpaceCowboy, If I Die First and CrazyEightyEight. This movement grew out of both the hardcore scene and the mainstream success that the emo rap scene gained the late-2010s.


title: Metalcore

text: The early 2000s included a wave of metalcore bands who placed significantly greater emphasis on melody. Melodic metalcore bands include Killswitch Engage, Avenged Sevenfold, As I Lay Dying, Trivium, Dead by April, All That Remains, Atreyu, Bullet for My Valentine, Bury Tomorrow, Darkest Hour, Shadows Fall, and August Burns Red. These groups took major influence, cues, and writing styles from Swedish melodic death metal bands, particularly At the Gates, In Flames, Arch Enemy and Soilwork. Melodic metalcore often employs clean vocals.


title: Metalcore

text: Mathcore began with the mid-1990s work of Converge, Botch Eso-Charis, Since the Fall, Coalesce,Training For Utopia, and The Dillinger Escape Plan. The term "mathcore" is meant to suggest an analogy with math rock. Mathcore is characterized by increased speed, technical riffing, and unusual time signatures. Bands such as Fear Before also combine the metalcore sound with odd time signatures, as well as progressive elements.


title: Metalcore

text: Deathcore is a fusion of metalcore and death metal. Deathcore is defined by breakdowns, blast beats and death metal riffs. Bands may also incorporate guitar solos and even riffs that are influenced by metalcore. New York-based death metal group Suffocation is credited as one of the main influences for the emergence of deathcore. Embodyments album "Embrace The Eternal" is a foundation for the modern Deathcore sound. Some examples of deathcore bands are Suicide Silence, Whitechapel, Knights of the Abyss, Carnifex, Chelsea Grin and Impending Doom.


title: Metalcore

text: Progressive metalcore is a fusion of progressive metal and metalcore characterized by highly technical lead guitar and djent-influenced breakdowns. Practitioners of the genre often rely heavily on "atmospheric" elements and complex instrumentation.


title: Metalcore

text: Nu metalcore is the musical fusion of nu metal and metalcore originating in the 2010s. Many notable groups take influence from deathcore, R&B, post-hardcore and industrial metal. Metalcore and deathcore groups such as Emmure, Of Mice & Men, Suicide Silence ("The Black Crown" album), and Issues all gained moderate popularity drawing influence from nu metal and metalcore.


title: Thirteenth Amendment to the United States Constitution

text: The Thirteenth Amendment (Amendment XIII) to the United States Constitution abolished slavery and involuntary servitude, except as punishment for a crime. The amendment was passed by the Senate on April 8, 1864, by the House of Representatives on January 31, 1865, and ratified by the required 27 of the then 36 states on December 6, 1865, and proclaimed on December 18. It was the first of the three Reconstruction Amendments adopted following the American Civil War.


text: President Abraham Lincoln's Emancipation Proclamation, effective on January 1, 1863, declared that the enslaved in Confederate-controlled areas were free. When they escaped to Union lines or federal forces (including now-former slaves) advanced south, emancipation occurred without any compensation to the former owners. Texas was the last Confederate territory reached by the Union army. On June 19, 1865—Juneteenth—U.S. Army general Gordon Granger arrived in Galveston, Texas, to proclaim the war had ended and so had slavery (in the Confederate states). In the slave-owning areas controlled by Union forces on January 1, 1863, state action was used to abolish slavery. The exceptions were New Jersey, Kentucky and Delaware, where all forms of forced labor were finally ended by the Thirteenth Amendment in December 1865.


text: In contrast to the other Reconstruction Amendments, the Thirteenth Amendment has rarely been cited in case law, but it has been used to strike down peonage and some race-based discrimination as "badges and incidents of slavery". The Thirteenth Amendment has also been invoked to empower Congress to make laws against modern forms of slavery, such as sex trafficking.


text: Since 1776, the Union had divided into states that allowed slavery and states that prohibited it. Slavery was implicitly recognized in the original Constitution in provisions such as Article I, Section 2, Clause 3, commonly known as the Three-Fifths Compromise, which provided that three-fifths of each state's enslaved population (“other persons”) was to be added to its free population for the purposes of apportioning seats in the United States House of Representatives, its number of Electoral votes, and direct taxes among the states. Article IV, Section 2, provided that slaves held under the laws of one state, who escaped to another state, did not become free, but remained slaves.


text: Though three million Confederate slaves were in fact eventually freed as a result of Lincoln's Emancipation Proclamation, their postwar status was uncertain. To ensure that abolition was beyond legal challenge, an amendment to the Constitution to that effect was initiated. On April 8, 1864, the Senate passed an amendment to abolish slavery. After one unsuccessful vote and extensive legislative maneuvering by the Lincoln administration, the House followed suit on January 31, 1865. The measure was swiftly ratified by nearly all Northern states, along with a sufficient number of border states (slave states not part of the Confederacy) up to the assassination of President Lincoln. However, the approval came via his successor, President Andrew Johnson, who encouraged the "reconstructed" Southern states of Alabama, North Carolina, and Georgia to agree, which brought the count to 27 states, leading to its adoption before the end of 1865.


text: Though the Amendment abolished slavery throughout the United States, some black Americans, particularly in the South, were subjected to other forms of involuntary labor, such as under the Black Codes, white supremacist violence, and selective enforcement of statutes, as well as other disabilities.


text: Slavery existed and was legal in the United States of America upon its founding in 1776. It was established by European colonization in all of the original thirteen American colonies of British America. Prior to the Thirteenth Amendment, the United States Constitution did not expressly use the words "slave" or "slavery" but included several provisions about unfree persons. The Three-Fifths Compromise, Article I, Section 2, Clause3 of the Constitution, allocated Congressional representation based "on the whole Number of free Persons" and "three-fifths of all other Persons". This clause was a compromise between Southern politicians who wished for enslaved African-Americans to be counted as 'persons' for congressional representation and Northern politicians rejecting these out of concern of too much power for the South, because representation in the new Congress would be based on population in contrast to the one-vote-for-one-state principle in the earlier Continental Congress. Under the Fugitive Slave Clause, Article IV, Section 2, Clause 3, "No person held to Service or Labour in one State" would be freed by escaping to another. allowed Congress to pass legislation outlawing the "Importation of Persons", which would not be passed until 1808. However, for purposes of the Fifth Amendment—which states that "No person shall... be deprived of life, liberty, or property, without due process of law"—slaves were understood as property. Although abolitionists used the Fifth Amendment to argue against slavery, it became part of the legal basis in "Dred Scott v. Sandford" (1857) for treating slaves as property.


text: Stimulated by the philosophy of the Declaration of Independence, between 1777 and 1804 every Northern state provided for the immediate or gradual abolition of slavery. Most of the slaves who were emancipated by such legislation were household servants. No Southern state did so, and the enslaved population of the South continued to grow, peaking at almost four million in 1861. An abolitionist movement headed by such figures as William Lloyd Garrison grew in strength in the North, calling for the end of slavery nationwide and exacerbating tensions between North and South. The American Colonization Society, an alliance between abolitionists who felt the races should be kept separated and slaveholders who feared the presence of freed blacks would encourage slave rebellions, called for the emigration of both free blacks and slaves to Africa, where they would establish independent colonies. Its views were endorsed by politicians such as Henry Clay, who feared that the American abolitionist movement would provoke a civil war. Proposals to eliminate slavery by constitutional amendment were introduced by Representative Arthur Livermore in 1818 and by John Quincy Adams in 1839, but failed to gain significant traction.


text: As the country continued to expand, the issue of slavery in its new territories became the dominant national issue. The Southern position was that slaves were property and therefore could be moved to the territories like all other forms of property. The 1820 Missouri Compromise provided for the admission of Missouri as a slave state and Maine as a free state, preserving the Senate's equality between the regions. In 1846, the Wilmot Proviso was introduced to a war appropriations bill to ban slavery in all territories acquired in the Mexican–American War; the Proviso repeatedly passed the House, but not the Senate. The Compromise of 1850 temporarily defused the issue by admitting California as a free state, instituting a stronger Fugitive Slave Act, banning the slave trade in Washington, D.C., and allowing New Mexico and Utah self-determination on the slavery issue.


text: Despite the compromise, tensions between North and South continued to rise over the subsequent decade, inflamed by, amongst other things, the publication of the 1852 anti-slavery novel "Uncle Tom's Cabin"; fighting between pro-slavery and abolitionist forces in Kansas, beginning in 1854; the 1857 "Dred Scott" decision, which struck down provisions of the Compromise of 1850; abolitionist John Brown's 1859 attempt to start a slave revolt at Harpers Ferry and the 1860 election of slavery critic Abraham Lincoln to the presidency. The Southern states seceded from the Union in the months following Lincoln's election, forming the Confederate States of America, and beginning the American Civil War.


text: Acting under presidential war powers, Lincoln issued the Emancipation Proclamation on September 22, 1862, with effect on January 1, 1863, which proclaimed the freedom of slaves in the ten states that were still in rebellion. In his State of the Union message to Congress on December 1, 1862, Lincoln also presented a plan for "gradual emancipation and deportation" of slaves. This plan envisioned three amendments to the Constitution. The first would have required the states to abolish slavery by January 1, 1900. Lincoln's Emancipation Proclamation then proceeded immediately freeing slaves in January 1863 but did not affect the status of slaves in the border states that had remained loyal to the Union. By December 1863, Lincoln again used his war powers and issued a "Proclamation for Amnesty and Reconstruction", which offered Southern states a chance to peacefully rejoin the Union if they immediately abolished slavery and collected loyalty oaths from 10% of their voting population. Southern states did not readily accept the deal, and the status of slavery remained uncertain.


text: In the final years of the Civil War, Union lawmakers debated various proposals for Reconstruction. Some of these called for a constitutional amendment to abolish slavery nationally and permanently. On December 14, 1863, a bill proposing such an amendment was introduced by Representative James Mitchell Ashley of Ohio. Representative James F. Wilson of Iowa soon followed with a similar proposal. On January 11, 1864, Senator John B. Henderson of Missouri submitted a joint resolution for a constitutional amendment abolishing slavery. The Senate Judiciary Committee, chaired by Lyman Trumbull of Illinois, became involved in merging different proposals for an amendment.


text: Radical Republicans led by Massachusetts Senator Charles Sumner and Pennsylvania Representative Thaddeus Stevens sought a more expansive version of the amendment. On February 8, 1864, Sumner submitted a constitutional amendment stating:


text: All persons are equal before the law, so that no person can hold another as a slave; and the Congress shall have power to make all laws necessary and proper to carry this declaration into effect everywhere in the United States.


text: Sumner tried to have his amendment sent to his committee, rather than the Trumbull-controlled Judiciary Committee, but the Senate refused. On February 10, the Senate Judiciary Committee presented the Senate with an amendment proposal based on drafts of Ashley, Wilson and Henderson.


text: The Committee's version used text from the Northwest Ordinance of 1787, which stipulates, "There shall be neither slavery nor involuntary servitude in the said territory, otherwise than in the punishment of crimes whereof the party shall have been duly convicted." Though using Henderson's proposed amendment as the basis for its new draft, the Judiciary Committee removed language that would have allowed a constitutional amendment to be adopted with only a majority vote in each House of Congress and ratification by two-thirds of the states (instead of two-thirds and three-fourths, respectively).


text: The Senate passed the amendment on April 8, 1864, by a vote of 38 to 6; two Democrats, Reverdy Johnson of Maryland and James Nesmith of Oregon voted for the amendment. However, just over two months later on June 15, the House failed to do so, with 93 in favor and 65 against, thirteen votes short of the two-thirds vote needed for passage; the vote split largely along party lines, with Republicans supporting and Democrats opposing. In the 1864 presidential race, former Free Soil Party candidate John C. Frémont threatened a third-party run opposing Lincoln, this time on a platform endorsing an anti-slavery amendment. The Republican Party platform had, as yet, failed to include a similar plank, though Lincoln endorsed the amendment in a letter accepting his nomination. Frémont withdrew from the race on September 22, 1864, and endorsed Lincoln.


text: With no Southern states represented, few members of Congress pushed moral and religious arguments in favor of slavery. Democrats who opposed the amendment generally made arguments based on federalism and states' rights. Some argued that the proposed change so violated the spirit of the Constitution it would not be a valid "amendment" but would instead constitute "revolution". Representative White, among other opponents, warned that the amendment would lead to full citizenship for blacks.


text: Republicans portrayed slavery as uncivilized and argued for abolition as a necessary step in national progress. Amendment supporters also argued that the slave system had negative effects on white people. These included the lower wages resulting from competition with forced labor, as well as repression of abolitionist whites in the South. Advocates said ending slavery would restore the First Amendment and other constitutional rights violated by censorship and intimidation in slave states.


text: White, Northern Republicans and some Democrats became excited about an abolition amendment, holding meetings and issuing resolutions. Many blacks though, particularly in the South, focused more on land ownership and education as the key to liberation. As slavery began to seem politically untenable, an array of Northern Democrats successively announced their support for the amendment, including Representative James Brooks, Senator Reverdy Johnson, and the powerful New York political machine known as Tammany Hall.


text: President Lincoln had had concerns that the Emancipation Proclamation of 1863 might be reversed or found invalid by the judiciary after the war. He saw constitutional amendment as a more permanent solution. He had remained outwardly neutral on the amendment because he considered it politically too dangerous. Nonetheless, Lincoln's 1864 election platform resolved to abolish slavery by constitutional amendment. After winning reelection in the election of 1864, Lincoln made the passage of the Thirteenth Amendment his top legislative priority. He began with his efforts in Congress during its "lame duck" session, in which many members of Congress had already seen their successors elected; most would be concerned about unemployment and lack of income, and none needed to fear the electoral consequences of cooperation. Popular support for the amendment mounted and Lincoln urged Congress on in his December 6, 1864 State of the Union Address: "there is only a question of "time" as to when the proposed amendment will go to the States for their action. And as it is to so go, at all events, may we not agree that the sooner the better?"


text: Lincoln instructed Secretary of State William H. Seward, Representative John B. Alley and others to procure votes by any means necessary, and they promised government posts and campaign contributions to outgoing Democrats willing to switch sides. Seward had a large fund for direct bribes. Ashley, who reintroduced the measure into the House, also lobbied several Democrats to vote in favor of the measure. Representative Thaddeus Stevens later commented that "the greatest measure of the nineteenth century was passed by corruption aided and abetted by the purest man in America"; however, Lincoln's precise role in making deals for votes remains unknown.


text: Republicans in Congress claimed a mandate for abolition, having gained in the elections for Senate and House. The 1864 Democratic vice-presidential nominee, Representative George H. Pendleton, led opposition to the measure. Republicans toned down their language of radical equality in order to broaden the amendment's coalition of supporters. In order to reassure critics worried that the amendment would tear apart the social fabric, some Republicans explicitly promised the amendment would leave patriarchy intact.


text: In mid-January 1865, Speaker of the House Schuyler Colfax estimated the amendment to be five votes short of passage. Ashley postponed the vote. At this point, Lincoln intensified his push for the amendment, making direct emotional appeals to particular members of Congress. On January 31, 1865, the House called another vote on the amendment, with neither side being certain of the outcome. With a total of 183 House members (one seat was vacant after Reuben Fenton was elected governor), 122 would have to vote "aye" to secure passage of the resolution; however, eight Democrats abstained, reducing the number to 117. Every Republican (84), Independent Republican (2), and Unconditional Unionist (16) supported the measure, as well as fourteen Democrats, almost all of them lame ducks, and three Unionists. The amendment finally passed by a vote of 119 to 56, narrowly reaching the required two-thirds majority. The House exploded into celebration, with some members openly weeping. Black onlookers, who had only been allowed to attend Congressional sessions since the previous year, cheered from the galleries.


text: While the Constitution does not provide the President any formal role in the amendment process, the joint resolution was sent to Lincoln for his signature. Under the usual signatures of the Speaker of the House and the President of the Senate, President Lincoln wrote the word "Approved" and added his signature to the joint resolution on February 1, 1865. On February 7, Congress passed a resolution affirming that the Presidential signature was unnecessary. The Thirteenth Amendment is the only ratified amendment signed by a President, although James Buchanan had signed the Corwin Amendment that the 36th Congress had adopted and sent to the states in March 1861.


text: On February 1, 1865, when the proposed amendment was submitted to the states for ratification, there were 36 states in the U.S., including those that had been in rebellion; at least 27 states had to ratify the amendment for it to come into force. By the end of February, 18 states had ratified the amendment. Among them were the ex-Confederate states of Virginia and Louisiana, where ratifications were submitted by Reconstruction governments. These, along with subsequent ratifications from Arkansas and Tennessee raised the issues of how many seceded states had legally valid legislatures; and if there were fewer legislatures than states, if Article V required ratification by three-fourths of the states or three-fourths of the legally valid state legislatures. President Lincoln in his last speech, on April 11, 1865, called the question about whether the Southern states were in or out of the Union a "pernicious abstraction". He declared they were not "in their proper practical relation with the Union"; whence everyone's object should be to restore that relation. Lincoln was assassinated three days later.