OpenRaiser/Intern-Atlas huggingface dataset:
Privacy-Preserving Trust Management Mechanisms from Private Matching Schemes
Venue: arXiv cs.CR 2013
Year: 2013

Cryptographic primitives are essential for constructing privacy-preserving communication mechanisms. There are situations in which two parties that do not know each other need to exchange sensitive information on the Internet. Trust management mechanisms make use of digital credentials and certificates in order to establish trust among these strangers. We address the problem of choosing which credentials are exchanged. During this process, each party should learn no information about the preferences of the other party other than strictly required for trust establishment. We present a method to reach an agreement on the credentials to be exchanged that preserves the privacy of the parties. Our method is based on secure two-party computation protocols for set intersection. Namely, it is constructed from private matching schemes.
What can Social Media teach us about protests? Analyzing the Chilean 2011-12 Student Movement's Network evolution through Twitter data
Venue: arXiv cs.SI 2013
Year: 2013

Using social media data -specially twitter -of the Chilean 2011-12 student movement, we study their social network evolution over time to analyze how leaders and participants self-organize and spread information. Based on a few key events of the student movement's timeline, we visualize the student network trajectory and analyze their structural and semantic properties. Therefore, in this paper we: i) describe the basic network topology of the 2011-12 Chilean massive student movement; ii) explore how the 180 key central nodes of the movement are connected, self-organize and spread information. We contend that this social media enabled massive movement is yet another manifestation of the network era, which leverages agents' socio-technical networks, and thus accelerates how agents coordinate, mobilize resources and enact collective intelligence.
Linearizability with Ownership Transfer
Venue: arXiv cs.LO 2013
Year: 2013

Linearizability is a commonly accepted notion of correctness for libraries of concurrent algorithms. Unfortunately, it assumes a complete isolation between a library and its client, with interactions limited to passing values of a given data type. This is inappropriate for common programming languages, where libraries and their clients can communicate via the heap, transferring the ownership of data structures, and can even run in a shared address space without any memory protection. In this paper, we present the first definition of linearizability that lifts this limitation and establish an Abstraction Theorem: while proving a property of a client of a concurrent library, we can soundly replace the library by its abstract implementation related to the original one by our generalisation of linearizability. This allows abstracting from the details of the library implementation while reasoning about the client. We also prove that linearizability with ownership transfer can be derived from the classical one if the library does not access some of data structures transferred to it by the client.
Interval colorings of complete bipartite graphs and trees
Venue: arXiv cs.DM 2013
Year: 2013

A translation from Russian of the work of R.R. Kamalian "Interval colorings of complete bipartite graphs and trees", Preprint of the Computing Centre of the Academy of Sciences of Armenia, Yerevan, 1989. (Was published by the decision of the Academic Council of the Computing Centre of the Academy of Sciences of Armenian SSR and Yerevan State University from 7.09.1989).
Evolutionary Extortion and Mischief: Zero Determinant strategies in iterated 2x2 games
Venue: arXiv cs.GT 2013
Year: 2013

This paper studies the mechanisms, implications, and potential applications of the recently discovered class of Zero Determinant (ZD) strategies in iterated 2x2 games. These strategies were reported to successfully extort pure economic maximizers, and to mischievously determine the set of feasible long-term payoffs in iterated Prisoners' Dilemma by enforcing linear constraints on both players' expected average scores. These results are generalized for all symmetric 2x2 games and a general Battle of the Sexes, exemplified by four common games. Additionally, a comparison to conventional strategies is made and typical ZD gameplay simulations are analyzed along with convergence speeds. Several response strategies are discussed, including a glance on how time preferences change previous results. Furthermore, a possibility of retaliation is presented: when maximin scores exceed the minimum symmetric payoff, it is possible to extort the extortioner. Finally, a summary of findings from evolutionary game theory shows that mischief is limited by its own malice. Nevertheless, this does not challenge the result that mindless economic maximization is subject to extortion: the study of ZD strategies reveals exciting new perspectives and opportunities in game theory, both evolutionary and classic.
Sparse Command Generator for Remote Control
Venue: arXiv cs.SY 2013
Year: 2013

In this article, we consider remote-controlled systems, where the command generator and the controlled object are connected with a bandwidth-limited communication link. In the remote-controlled systems, efficient representation of control commands is one of the crucial issues because of the bandwidth limitations of the link. We propose a new representation method for control commands based on compressed sensing. In the proposed method, compressed sensing reduces the number of bits in each control signal by representing it as a sparse vector. The compressed sensing problem is solved by an L1-L2 optimization, which can be effectively implemented with an iterative shrinkage algorithm. A design example also shows the effectiveness of the proposed method.
Independent Set, Induced Matching, and Pricing: Connections and Tight (Subexponential Time) Approximation Hardnesses
Venue: arXiv cs.CC 2013
Year: 2013

We present a series of almost settled inapproximability results for three fundamental problems. The first in our series is the subexponential-time inapproximability of the maximum independent set problem, a question studied in the area of parameterized complexity. The second is the hardness of approximating the maximum induced matching problem on bounded-degree bipartite graphs. The last in our series is the tight hardness of approximating the k-hypergraph pricing problem, a fundamental problem arising from the area of algorithmic game theory. In particular, assuming the Exponential Time Hypothesis, our two main results are: - For any r larger than some constant, any r-approximation algorithm for the maximum independent set problem must run in at least 2^{n^{1-ε}/r^{1+ε}} time. This nearly matches the upper bound of 2^{n/r} (Cygan et al., 2008). It also improves some hardness results in the domain of parameterized complexity (e.g., Escoffier et al., 2012 and Chitnis et al., 2013) - For any k larger than some constant, there is no polynomial time min (k^{1-ε}, n^{1/2-ε})-approximation algorithm for the k-hypergraph pricing problem, where n is the number of vertices in an input graph. This almost matches the upper bound of min (O(k), \tilde O(\sqrt{n})) (by Balcan and Blum, 2007 and an algorithm in this paper). We note an interesting fact that, in contrast to n^{1/2-ε} hardness for polynomial-time algorithms, the k-hypergraph pricing problem admits n^δ approximation for any δ>0 in quasi-polynomial time. This puts this problem in a rare approximability class in which approximability thresholds can be improved significantly by allowing algorithms to run in quasi-polynomial time.
An efficient ant based qos aware intelligent temporally ordered routing algorithm for manets
Venue: arXiv cs.NI 2013
Year: 2013

A Mobile Ad hoc network (MANET) is a self configurable network connected by wireless links. This type of network is only suitable for temporary communication links as it is infrastructure-less and there is no centralised control. Providing QoS aware routing is a challenging task in this type of network due to dynamic topology and limited resources. The main purpose of QoS aware routing is to find a feasible path from source to destination which will satisfy two or more end to end QoS constrains. Therefore, the task of designing an efficient routing algorithm which will satisfy all the quality of service requirements and be robust and adaptive is considered as a highly challenging problem. In this work we have designed a new efficient and energy aware multipath routing algorithm based on ACO framework, inspired by the behaviours of biological ants. Basically by considering QoS constraints and artificial ants we have designed an intelligent version of classical Temporally Ordered Routing Algorithm (TORA) which will increase network lifetime and decrease packet loss and average end to end delay that makes this algorithm suitable for real time and multimedia applications.
Extended Distributed Learning Automata:A New Method for Solving Stochastic Graph Optimization Problems
Venue: arXiv cs.AI 2013
Year: 2013

In this paper, a new structure of cooperative learning automata so-called extended learning automata (eDLA) is introduced. Based on the proposed structure, a new iterative randomized heuristic algorithm for finding optimal sub-graph in a stochastic edge-weighted graph through sampling is proposed. It has been shown that the proposed algorithm based on new networked-structure can be to solve the optimization problems on stochastic graph through less number of sampling in compare to standard sampling. Stochastic graphs are graphs in which the edges have an unknown distribution probability weights. Proposed algorithm uses an eDLA to find a policy that leads to an induced sub-graph that satisfies some restrictions such as minimum or maximum weight (length). At each stage of the proposed algorithm, eDLA determines which edges to be sampled. This eDLA-based proposed sampling method may result in decreasing unnecessary samples and hence decreasing the time that algorithm requires for finding the optimal sub-graph. It has been shown that proposed method converge to optimal solution, furthermore the probability of this convergence can be made arbitrarily close to 1 by using a sufficiently small learning rate. A new variance-aware threshold value was proposed that can be improving significantly convergence rate of the proposed eDLA-based algorithm. It has been shown that the proposed algorithm is competitive in terms of the quality of the solution
Improved Quality of Service Protocol for Real Time Traffic in MANET
Venue: arXiv cs.NI 2013
Year: 2013

The technologies like Wi-Fi, Blue tooth, WiMax etc. have made Mobile Ad hoc Networks common in our Real life. Multi-media applications need to be supported on MANET. A certain level of QoS (Quality of Service) support is essential for Real time data. Our proposed protocol provides the required QoS without having negative impact on Best Effort data traffic. An efficient rout discovery mechanism for AODV routing protocol as well as transmission technique for real time data are proposed. This technique gives more transmission opportunities to real time data traffic results in decreasing transmission delay and increasing throughput. A modified version of the popular AODV routing protocol to provide QoS guarantee for real time traffic in MANETs is proposed. The simulation shows better performance results for proposed protocol over the basic AODV.
Effective Construction of a Class of Bent Quadratic Boolean Functions
Venue: arXiv cs.IT 2013
Year: 2013

In this paper, we consider the characterization of the bentness of quadratic Boolean functions of the form $f(x)=\sum_{i=1}^{\frac{m}{2}-1} Tr^n_1(c_ix^{1+2^{ei}})+ Tr_1^{n/2}(c_{m/2}x^{1+2^{n/2}}) ,$ where $n=me$, $m$ is even and $c_i\in GF(2^e)$. For a general $m$, it is difficult to determine the bentness of these functions. We present the bentness of quadratic Boolean function for two cases: $m=2^vp^r$ and $m=2^vpq$, where $p$ and $q$ are two distinct primes. Further, we give the enumeration of quadratic bent functions for the case $m=2^vpq$.
Discretized Gabor Frames of Totally Positive Functions
Venue: arXiv cs.IT 2013
Year: 2013

In this paper a large class of universal windows for Gabor frames (Weyl-Heisenberg frames) is constructed. These windows have the fundamental property that every overcritical rectangular lattice generates a Gabor frame. Likewise, every undercritical rectangular lattice generates a Riesz sequence.
Can Agent Intelligence be used to Achieve Fault Tolerant Parallel Computing Systems?
Venue: arXiv cs.DC 2013
Year: 2013

The work reported in this paper is motivated towards validating an alternative approach for fault tolerance over traditional methods like checkpointing that constrain efficacious fault tolerance. Can agent intelligence be used to achieve fault tolerant parallel computing systems? If so, "What agent capabilities are required for fault tolerance?", "What parallel computational tasks can benefit from such agent capabilities?" and "How can agent capabilities be implemented for fault tolerance?" need to be addressed. Cognitive capabilities essential for achieving fault tolerance through agents are considered. Parallel reduction algorithms are identified as a class of algorithms that can benefit from cognitive agent capabilities. The Message Passing Interface is utilized for implementing an intelligent agent based approach. Preliminary results obtained from the experiments validate the feasibility of an agent based approach for achieving fault tolerance in parallel computing systems.
Low-Complexity Sphere Decoding of Polar Codes based on Optimum Path Metric
Venue: arXiv cs.IT 2013
Year: 2013

Sphere decoding (SD) of polar codes is an efficient method to achieve the error performance of maximum likelihood (ML) decoding. But the complexity of the conventional sphere decoder is still high, where the candidates in a target sphere are enumerated and the radius is decreased gradually until no available candidate is in the sphere. In order to reduce the complexity of SD, a stack SD (SSD) algorithm with an efficient enumeration is proposed in this paper. Based on a novel path metric, SSD can effectively narrow the search range when enumerating the candidates within a sphere. The proposed metric follows an exact ML rule and takes the full usage of the whole received sequence. Furthermore, another very simple metric is provided as an approximation of the ML metric in the high signal-to-noise ratio regime. For short polar codes, simulation results over the additive white Gaussian noise channels show that the complexity of SSD based on the proposed metrics is up to 100 times lower than that of the conventional SD.
Robotic Message Ferrying for Wireless Networks using Coarse-Grained Backpressure Control
Venue: arXiv cs.NI 2013
Year: 2013

We formulate the problem of robots ferrying messages between statically-placed source and sink pairs that they can communicate with wirelessly. We first analyze the capacity region for this problem under both ideal (arbitrarily high velocity, long scheduling periods) and realistic conditions. We indicate how robots could be scheduled optimally to satisfy any arrival rate in the capacity region, given prior knowledge about arrival rates. We find that if the number of robots allocated grows proportionally with the number of source-sink pairs, then the capacity of the network scales as $Θ(1)$, similar to what was shown previously by Grossglauser and Tse for uncontrolled mobility; however, in contrast to that prior result, we also find that with controlled mobility this constant capacity scaling can be obtained while ensuring finite delay. We then consider the setting where the arrival rates are unknown and present a coarse-grained backpressure message ferrying algorithm (CBMF) for it. In CBMF, the robots are matched to sources and sinks once every epoch to maximize a queue-differential-based weight. The matching controls both motion and transmission for each robot: if a robot is matched to a source, it moves towards that source and collects data from it; and if it is matched to a sink, it moves towards that sink and transmits data to it. We show through analysis and simulations the conditions under which CBMF can stabilize the network. We show that the maximum achievable stable throughput with this policy tends to the ideal capacity as the schedule duration and robot velocity increase.
Semistability-Based Convergence Analysis for Paracontracting Multiagent Coordination Optimization
Venue: arXiv cs.SY 2013
Year: 2013

This sequential technical report extends some of the previous results we posted at arXiv:1306.0225.
Gap Theorems for the Delay of Circuits Simulating Finite Automata
Venue: arXiv cs.CC 2013
Year: 2013

We study the delay (also known as depth) of circuits that simulate finite automata, showing that only certain growth rates (as a function of the number $n$ of steps simulated) are possible. A classic result due to Ofman (rediscovered and popularized by Ladner and Fischer) says that delay $O(\log n)$ is always sufficient. We show that if the automaton is "generalized definite", then delay O(1) is sufficient, but otherwise delay $Ω(\log n)$ is necessary; there are no intermediate growth rates. We also consider "physical" (rather than "logical") delay, whereby we consider the lengths of wires when inputs and outputs are laid out along a line. In this case, delay O(n) is clearly always sufficient. We show that if the automaton is "definite", then delay O(1) is sufficient, but otherwise delay $Ω(n)$ is necessary; again there are no intermediate growth rates. Inspired by an observation of Burks, Goldstein and von Neumann concerning the average delay due to carry propagation in ripple-carry adders, we derive conditions for the average physical delay to be reduced from O(n) to $O(\log n)$, or to O(1), when the inputs are independent and uniformly distributed random variables; again there are no intermediate growth rates. Finally we consider an extension of this last result to a situation in which the inputs are not independent and uniformly distributed, but rather are produced by a non-stationary Markov process, and in which the computation is not performed by a single automaton, but rather by a sequence of automata acting in alternating directions.
Phase Retrieval for Sparse Signals: Uniqueness Conditions
Venue: arXiv cs.IT 2013
Year: 2013

In a variety of fields, in particular those involving imaging and optics, we often measure signals whose phase is missing or has been irremediably distorted. Phase retrieval attempts the recovery of the phase information of a signal from the magnitude of its Fourier transform to enable the reconstruction of the original signal. A fundamental question then is: "Under which conditions can we uniquely recover the signal of interest from its measured magnitudes?" In this paper, we assume the measured signal to be sparse. This is a natural assumption in many applications, such as X-ray crystallography, speckle imaging and blind channel estimation. In this work, we derive a sufficient condition for the uniqueness of the solution of the phase retrieval (PR) problem for both discrete and continuous domains, and for one and multi-dimensional domains. More precisely, we show that there is a strong connection between PR and the turnpike problem, a classic combinatorial problem. We also prove that the existence of collisions in the autocorrelation function of the signal may preclude the uniqueness of the solution of PR. Then, assuming the absence of collisions, we prove that the solution is almost surely unique on 1-dimensional domains. Finally, we extend this result to multi-dimensional signals by solving a set of 1-dimensional problems. We show that the solution of the multi-dimensional problem is unique when the autocorrelation function has no collisions, significantly improving upon a previously known result.
Membership in social networks and the application in information filtering
Venue: arXiv cs.IR 2013
Year: 2013

During the past a few years, users' membership in the online system (i.e. the social groups that online users joined) are wildly investigated. Most of these works focus on the detection, formulation and growth of online communities. In this paper, we study users' membership in a coupled system which contains user-group and user-object bipartite networks. By linking users' membership information and their object selection, we find that the users who have collected only a few objects are more likely to be "influenced" by the membership when choosing objects. Moreover, we observe that some users may join many online communities though they collected few objects. Based on these findings, we design a social diffusion recommendation algorithm which can effectively solve the user cold-start problem. Finally, we propose a personalized combination of our method and the hybrid method in [PNAS 107, 4511 (2010)], which leads to a further improvement in the overall recommendation performance.
First experiences with the Intel MIC architecture at LRZ
Venue: arXiv cs.PF 2013
Year: 2013

With the rapidly growing demand for computing power new accelerator based architectures have entered the world of high performance computing since around 5 years. In particular GPGPUs have recently become very popular, however programming GPGPUs using programming languages like CUDA or OpenCL is cumbersome and error-prone. Trying to overcome these difficulties, Intel developed their own Many Integrated Core (MIC) architecture which can be programmed using standard parallel programming techniques like OpenMP and MPI. In the beginning of 2013, the first production-level cards named Intel Xeon Phi came on the market. LRZ has been considered by Intel as a leading research centre for evaluating coprocessors based on the MIC architecture since 2010 under strict NDA. Since the Intel Xeon Phi is now generally available, we can share our experience on programming Intel's new MIC architecture.
Normalized Google Distance of Multisets with Applications
Venue: arXiv cs.IR 2013
Year: 2013

Normalized Google distance (NGD) is a relative semantic distance based on the World Wide Web (or any other large electronic database, for instance Wikipedia) and a search engine that returns aggregate page counts. The earlier NGD between pairs of search terms (including phrases) is not sufficient for all applications. We propose an NGD of finite multisets of search terms that is better for many applications. This gives a relative semantics shared by a multiset of search terms. We give applications and compare the results with those obtained using the pairwise NGD. The derivation of NGD method is based on Kolmogorov complexity.