Computability theory is part of computer science. Scientists want to know what can be computed, and what can not.
There is a model of a computer that is used for this. It is called the Turing machine. A Turing machine basically is a special typewriter with an endless ribbon. The machine is named after the mathematician Alan Turing.
A problem is "computable" if it can be expressed in such a way that a Turing machine can solve it.
One of the best known examples is the Halting problem. The task is to write a program which says for all programs whether they will finally stop. This is impossible to decide. Mathematicians say the problem is undecidable.
Batman (city)
Batman is a city in southeast Turkey. It is the capital (city) of the province with the same name. In 2010, 325,000 people lived there. There are many Kurds in that area. The area has much oil and gas.
There is a railway track at Kurtalan, near this city. The track runs all the way to Istanbul. There is also an airport near Batman. The name is short for the Bati Raman mountains.
Typewriter
A typewriter is a machine that is for typing on a piece of paper instead of writing by hand. It has keys for typing letters, numerals, and symbols one at a time. Typewriters were created in 1829. Typewriters were originally invented to make writing faster and printing. The earliest typing was done on stone, clay, or metal sheets by inscribing them.
A typewriter does not have computer memory. As with writing with a pen, it is difficult to correct mistakes. One advantage is that many of them are not electrical, so you do not need to plug them in. Hackers cannot see what you have typed. On many typewriters, a separate type element (called a typebar) corresponds to each key. The first commercial typewriters were introduced in 1874. They did not become common in offices until after the mid-1880s.
Typewriters quickly became a necessary tool for almost all writing other than personal handwritten letters. They were used a lot by professional writers, in offices, and for business correspondence in private homes. Typewriters were common in most offices up to the 1980s. After that, computers often replaced them. Nevertheless, typewriters are still common in some parts of the world. They are needed for a few specific applications, and they are popular in certain subcultures. Early typewriters, and later cheap ones, were "manual" typewriters. This means they were powered completely by the user. After the mid-20th century, electric typewriters with a motor became most common.
Nocturnal animals
Nocturnal (Latin: "nox" - night, darkness) animals are animals that are mainly active during the night. They hunt or feed during the night, and sleep during the day. Diurnal animals do it the other way around.
Scientists sometimes use the word "crepuscular" to describe nocturnal animals that are not active when it is very dark at night; they are mostly active near dawn, dusk, and sometimes when the moon makes a lot of light.
Many nocturnal animals have good night vision. Their large eyes may also be highly reflective when a bright light flashes them.
Censorship
Censorship is when an authority (such as a government or religion) cuts out or suppresses communication.
This has been done widely. All countries, religions and societies have their limits as to what can be said, or written or communication by art or nowadays by computer.
Certain facts are changed or removed on purpose. This may be done because it is considered wrong, harmful, sensitive, or inconvenient to the government or other authority. This can be done for different reasons.
A censor is a person whose job is to look at all types of media and remove material. There are many reasons to censor something, like protecting military secrets, stopping immoral or anti-religious works, or keeping political power. Censorship is almost always used as an insult, and there is much debate over what censorship is and when it is okay.
When there is freedom of speech and freedom of the press, most information can published. However, even in developed countries with much freedom of the press, there are some things that cannot be published. For example, journalists are usually not allowed to publish many secrets about the military, like where troops will be sent on a mission. Pornography is censored in some countries because it is seen as not moral. For these reasons, the government might arrest anyone who publishes it.
Most often things are censored for one or more of the following reasons:
There is much debate about when censorship should be allowed. For example, U.S. President Richard Nixon censored the New York Times when they tried to publish articles about the Pentagon Papers, a group of classified military documents that showed that Nixon and the military lied about the Vietnam War. The Supreme Court in New York Times Co v. United States overturned the censorship, saying that Nixon had not shown it would be dangerous to the military, just embarrassing. In other countries, journalists and bloggers (who are usually not seen as journalists) are sometimes arrested for saying bad things about the government. In Egypt, Kareem Amer was famously arrested for insulting Islam and calling the president of Egypt, Hosni Mubarak, a dictator.
Governments are not the only ones who censor information. For example, when the history department at Middlebury College did not allow professors to accept Wikipedia as a source in papers, some said it was censorship. This was because the department was telling professors (who usually have academic freedom) what works they should or should not accept. Sometimes, a group or a website will not allow some facts, articles, and pictures that they do not think should be seen. There is much debate over the difference between censorship and editing, that is, deciding what should or should not be published.
Sometimes there is censorship of knowledge because it is believed that the average person can be harmed by access to it.
Slate Magazine wrote that in the 18th century the French king’s council stopped the distribution of Encyclopédie because it was “destroying royal authority and encouraging a spirit of independence and revolt,”
The Chinese government has blocked the Chinese-language Wikipedia since June 2015.
On July 16, 2019 the National Post ran an article about a woman who was banned fromTwitter. Lindsay Shepherd who is described as a Free speech advocate claimed that twitter has been too eager to censor right-wing public figures. Shepherd was a teaching assistant at Wilfrid Laurier University.
Czestochowa
Częstochowa is a city in south Poland on the Warta River. It has 248,894 residents. It has been in the Silesian Voivodeship (administrative division) since 1999, and was once the capital of Częstochowa Voivodship (1975-1998).
The town is known for the famous monastery of Jasna Góra Monastery, which is the home of the Black Madonna painting, a shrine of the Virgin Mary. Every year, thousands of people from all over the world come to Częstochowa to see it.
The name Częstochowa means Częstoch's place, and comes from the name of a person, Częstoch. It is mentioned in medieval documents also as Częstobor and Częstomir. Częstochowa is also known as Czestochowa, Czenstochov, and Chenstochov.
Currently, the city is one of the main tourist attractions in the area. It attracts hundreds of thousands of visitors every year.
The Black Madonna of Częstochowa, kept at the Jasna Góra Monastery, is a very popular attraction.
Voivodeships of Poland
A Voivodeship is one of 16 different divisions of land in Poland. The word comes from the Polish ""wojewoda"" meaning a governor.
50s
"This is an article about the years 50 AD to 59 AD. Sometimes, "the 50s" is used for the 1950s".
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