OpenRaiser/Intern-Atlas huggingface dataset:
New directions in mechanism design
Venue: arXiv cs.GT 2005
Year: 2005

Mechanism design uses the tools of economics and game theory to design rules of interaction for economic transactions that will,in principle, yield some de- sired outcome. In the last few years this field has received much interest of researchers in computer science, especially with the Internet developing as a platform for communications and connections among enormous numbers of computers and humans. Arguably the most positive result in mechanism de- sign is truthful and there are only one general truthful mechanisms so far : the generalized Vickrey-Clarke-Groves (VCG) mechanism. But VCG mecha- nism has one shortage: The implementation of truthfulness is on the cost of decreasing the revenue of the mechanism. (e.g., Ning Chen and Hong Zhu. [1999]). We introduce three new characters of mechanism:partly truthful, criti- cal, consistent, and introduce a new mechanism: X mechanism that satisfy the above three characters. Like VCG mechanism, X mechanism also generalizes from Vickery Auction and is consistent with Vickery auction in many ways, but the extended methods used in X mechanism is different from that in VCG mechanism . This paper will demonstrate that X mechanism better than VCG mechanism in optimizing utility of mechanism, which is the original intention of mechanism design. So partly truthful,critical and consistent are at least as important as truthful in mechanism design, and they beyond truthful in many situations.As a result, we conclude that partly truthful,critical and consistent are three new directions in mechanism design.
Understanding physics from interconnected data
Venue: arXiv cs.CV 2005
Year: 2005

Metal melting on release after explosion is a physical system far from quilibrium. A complete physical model of this system does not exist, because many interrelated effects have to be considered. General methodology needs to be developed so as to describe and understand physical phenomena involved. The high noise of the data, moving blur of images, the high degree of uncertainty due to the different types of sensors, and the information entangled and hidden inside the noisy images makes reasoning about the physical processes very difficult. Major problems include proper information extraction and the problem of reconstruction, as well as prediction of the missing data. In this paper, several techniques addressing the first problem are given, building the basis for tackling the second problem.
Collaborative tagging as a tripartite network
Venue: arXiv cs.DS 2005
Year: 2005

We describe online collaborative communities by tripartite networks, the nodes being persons, items and tags. We introduce projection methods in order to uncover the structures of the networks, i.e. communities of users, genre families... To do so, we focus on the correlations between the nodes, depending on their profiles, and use percolation techniques that consist in removing less correlated links and observing the shaping of disconnected islands. The structuring of the network is visualised by using a tree representation. The notion of diversity in the system is also discussed.
Statistical Parameters of the Novel "Perekhresni stezhky" ("The Cross-Paths") by Ivan Franko
Venue: arXiv cs.CL 2005
Year: 2005

In the paper, a complex statistical characteristics of a Ukrainian novel is given for the first time. The distribution of word-forms with respect to their size is studied. The linguistic laws by Zipf-Mandelbrot and Altmann-Menzerath are analyzed.
On the Development of the Intersection of a Plane with a Polytope
Venue: arXiv cs.CG 2006
Year: 2006

Define a ``slice'' curve as the intersection of a plane with the surface of a polytope, i.e., a convex polyhedron in three dimensions. We prove that a slice curve develops on a plane without self-intersection. The key tool used is a generalization of Cauchy's arm lemma to permit nonconvex ``openings'' of a planar convex chain.
On the suitability of the 2 x 2 games for studying reciprocal cooperation and kin selection
Venue: arXiv cs.GT 2006
Year: 2006

The 2 x 2 games, in particular the Prisoner's Dilemma, have been extensively used in studies into reciprocal cooperation and, to a lesser extent, kin selection. This paper examines the suitability of the 2 x 2 games for modelling the evolution of cooperation through reciprocation and kin selection. This examination is not restricted to the Prisoner's Dilemma, but includes the other non-trivial symmetric 2 x 2 games. We show that the popularity of the Prisoner's Dilemma for modelling social and biotic interaction is justified by its superiority according to these criteria. Indeed, the Prisoner's Dilemma is unique in providing the simplest support for reciprocal cooperation, and additive kin-selected altruism. However, care is still required in choosing the particular Prisoner's Dilemma payoff matrix to use. This paper reviews the impact of non-linear payoffs for the application of Hamilton's rule to typical altruistic interactions, and derives new results for cases in which the roles of potential altruist and beneficiary are separated. In doing so we find the same equilibrium condition holds in continuous games between relatives, and in discrete games with roles.
Finding Traitors in Secure Networks Using Byzantine Agreements
Venue: arXiv cs.CR 2006
Year: 2006

Secure networks rely upon players to maintain security and reliability. However not every player can be assumed to have total loyalty and one must use methods to uncover traitors in such networks. We use the original concept of the Byzantine Generals Problem by Lamport, and the more formal Byzantine Agreement describe by Linial, to nd traitors in secure networks. By applying general fault-tolerance methods to develop a more formal design of secure networks we are able to uncover traitors amongst a group of players. We also propose methods to integrate this system with insecure channels. This new resiliency can be applied to broadcast and peer-to-peer secure communication systems where agents may be traitors or become unreliable due to faults.
Generalized Strong Preservation by Abstract Interpretation
Venue: arXiv cs.LO 2006
Year: 2006

Standard abstract model checking relies on abstract Kripke structures which approximate concrete models by gluing together indistinguishable states, namely by a partition of the concrete state space. Strong preservation for a specification language L encodes the equivalence of concrete and abstract model checking of formulas in L. We show how abstract interpretation can be used to design abstract models that are more general than abstract Kripke structures. Accordingly, strong preservation is generalized to abstract interpretation-based models and precisely related to the concept of completeness in abstract interpretation. The problem of minimally refining an abstract model in order to make it strongly preserving for some language L can be formulated as a minimal domain refinement in abstract interpretation in order to get completeness w.r.t. the logical/temporal operators of L. It turns out that this refined strongly preserving abstract model always exists and can be characterized as a greatest fixed point. As a consequence, some well-known behavioural equivalences, like bisimulation, simulation and stuttering, and their corresponding partition refinement algorithms can be elegantly characterized in abstract interpretation as completeness properties and refinements.
A Logic for Reasoning about Evidence
Venue: arXiv cs.AI 2006
Year: 2006

We introduce a logic for reasoning about evidence that essentially views evidence as a function from prior beliefs (before making an observation) to posterior beliefs (after making the observation). We provide a sound and complete axiomatization for the logic, and consider the complexity of the decision problem. Although the reasoning in the logic is mainly propositional, we allow variables representing numbers and quantification over them. This expressive power seems necessary to capture important properties of evidence.
Content Based Image Retrieval with Mobile Agents and Steganography
Venue: arXiv cs.CR 2006
Year: 2006

In this paper we present an image retrieval system based on Gabor texture features, steganography, and mobile agents.. By employing the information hiding technique, the image attributes can be hidden in an image without degrading the image quality. Thus the image retrieval process becomes simple. Java based mobile agents manage the query phase of the system. Based on the simulation results, the proposed system not only shows the efficiency in hiding the attributes but also provides other advantages such as: (1) fast transmission of the retrieval image to the receiver, (2) searching made easy.
Learning nonsingular phylogenies and hidden Markov models
Venue: arXiv cs.LG 2006
Year: 2006

In this paper we study the problem of learning phylogenies and hidden Markov models. We call a Markov model nonsingular if all transition matrices have determinants bounded away from 0 (and 1). We highlight the role of the nonsingularity condition for the learning problem. Learning hidden Markov models without the nonsingularity condition is at least as hard as learning parity with noise, a well-known learning problem conjectured to be computationally hard. On the other hand, we give a polynomial-time algorithm for learning nonsingular phylogenies and hidden Markov models.
On the Scalability of Cooperative Time Synchronization in Pulse-Connected Networks
Venue: arXiv cs.IT 2006
Year: 2006

The problem of time synchronization in dense wireless networks is considered. Well established synchronization techniques suffer from an inherent scalability problem in that synchronization errors grow with an increasing number of hops across the network. In this work, a model for communication in wireless networks is first developed, and then the model is used to define a new time synchronization mechanism. A salient feature of the proposed method is that, in the regime of asymptotically dense networks, it can average out all random errors and maintain global synchronization in the sense that all nodes in the multi-hop network can see identical timing signals. This is irrespective of the distance separating any two nodes.
Searching Monotone Multi-dimensional Arrays
Venue: arXiv cs.DS 2006
Year: 2006

In this paper we investigate the problem of searching monotone multi-dimensional arrays. We generalize Linial and Saks' search algorithm \cite{LS1} for monotone 3-dimensional arrays to $d$-dimensions with $d\geq 4$. Our new search algorithm is asymptotically optimal for $d=4$.
Approximate reasoning for real-time probabilistic processes
Venue: arXiv cs.LO 2006
Year: 2006

We develop a pseudo-metric analogue of bisimulation for generalized semi-Markov processes. The kernel of this pseudo-metric corresponds to bisimulation; thus we have extended bisimulation for continuous-time probabilistic processes to a much broader class of distributions than exponential distributions. This pseudo-metric gives a useful handle on approximate reasoning in the presence of numerical information -- such as probabilities and time -- in the model. We give a fixed point characterization of the pseudo-metric. This makes available coinductive reasoning principles for reasoning about distances. We demonstrate that our approach is insensitive to potentially ad hoc articulations of distance by showing that it is intrinsic to an underlying uniformity. We provide a logical characterization of this uniformity using a real-valued modal logic. We show that several quantitative properties of interest are continuous with respect to the pseudo-metric. Thus, if two processes are metrically close, then observable quantitative properties of interest are indeed close.
Optimal space-time codes for the MIMO amplify-and-forward cooperative channel
Venue: arXiv cs.IT 2006
Year: 2006

In this work, we extend the non-orthogonal amplify-and-forward (NAF) cooperative diversity scheme to the MIMO channel. A family of space-time block codes for a half-duplex MIMO NAF fading cooperative channel with N relays is constructed. The code construction is based on the non-vanishing determinant criterion (NVD) and is shown to achieve the optimal diversity-multiplexing tradeoff (DMT) of the channel. We provide a general explicit algebraic construction, followed by some examples. In particular, in the single relay case, it is proved that the Golden code and the 4x4 Perfect code are optimal for the single-antenna and two-antenna case, respectively. Simulation results reveal that a significant gain (up to 10dB) can be obtained with the proposed codes, especially in the single-antenna case.
Retinal Vessel Segmentation Using the 2-D Morlet Wavelet and Supervised Classification
Venue: arXiv cs.CV 2006
Year: 2006

We present a method for automated segmentation of the vasculature in retinal images. The method produces segmentations by classifying each image pixel as vessel or non-vessel, based on the pixel's feature vector. Feature vectors are composed of the pixel's intensity and continuous two-dimensional Morlet wavelet transform responses taken at multiple scales. The Morlet wavelet is capable of tuning to specific frequencies, thus allowing noise filtering and vessel enhancement in a single step. We use a Bayesian classifier with class-conditional probability density functions (likelihoods) described as Gaussian mixtures, yielding a fast classification, while being able to model complex decision surfaces and compare its performance with the linear minimum squared error classifier. The probability distributions are estimated based on a training set of labeled pixels obtained from manual segmentations. The method's performance is evaluated on publicly available DRIVE and STARE databases of manually labeled non-mydriatic images. On the DRIVE database, it achieves an area under the receiver operating characteristic (ROC) curve of 0.9598, being slightly superior than that presented by the method of Staal et al.
Spectral approach to linear programming bounds on codes
Venue: arXiv cs.IT 2006
Year: 2006

We give new proofs of asymptotic upper bounds of coding theory obtained within the frame of Delsarte's linear programming method. The proofs rely on the analysis of eigenvectors of some finite-dimensional operators related to orthogonal polynomials. The examples of the method considered in the paper include binary codes, binary constant-weight codes, spherical codes, and codes in the projective spaces.
Competing with wild prediction rules
Venue: arXiv cs.LG 2006
Year: 2006

We consider the problem of on-line prediction competitive with a benchmark class of continuous but highly irregular prediction rules. It is known that if the benchmark class is a reproducing kernel Hilbert space, there exists a prediction algorithm whose average loss over the first N examples does not exceed the average loss of any prediction rule in the class plus a "regret term" of O(N^(-1/2)). The elements of some natural benchmark classes, however, are so irregular that these classes are not Hilbert spaces. In this paper we develop Banach-space methods to construct a prediction algorithm with a regret term of O(N^(-1/p)), where p is in [2,infty) and p-2 reflects the degree to which the benchmark class fails to be a Hilbert space.
Book review "The Haskell Road to Logic, Maths and Programming"
Venue: arXiv cs.PL 2006
Year: 2006

The textbook by Doets and van Eijck puts the Haskell programming language systematically to work for presenting a major piece of logic and mathematics. The reader is taken through chapters on basic logic, proof recipes, sets and lists, relations and functions, recursion and co-recursion, the number systems, polynomials and power series, ending with Cantor's infinities. The book uses Haskell for the executable and strongly typed manifestation of various mathematical notions at the level of declarative programming. The book adopts a systematic but relaxed mathematical style (definition, example, exercise, ...); the text is very pleasant to read due to a small amount of anecdotal information, and due to the fact that definitions are fluently integrated in the running text. An important goal of the book is to get the reader acquainted with reasoning about programs.
On the Joint Source-Channel Coding Error Exponent for Discrete Memoryless Systems: Computation and Comparison with Separate Coding
Venue: arXiv cs.IT 2006
Year: 2006

We investigate the computation of Csiszar's bounds for the joint source-channel coding (JSCC) error exponent, E_J, of a communication system consisting of a discrete memoryless source and a discrete memoryless channel. We provide equivalent expressions for these bounds and derive explicit formulas for the rates where the bounds are attained. These equivalent representations can be readily computed for arbitrary source-channel pairs via Arimoto's algorithm. When the channel's distribution satisfies a symmetry property, the bounds admit closed-form parametric expressions. We then use our results to provide a systematic comparison between the JSCC error exponent E_J and the tandem coding error exponent E_T, which applies if the source and channel are separately coded. It is shown that E_T <= E_J <= 2E_T. We establish conditions for which E_J > E_T and for which E_J = 2E_T. Numerical examples indicate that E_J is close to 2E_T for many source-channel pairs. This gain translates into a power saving larger than 2 dB for a binary source transmitted over additive white Gaussian noise channels and Rayleigh fading channels with finite output quantization. Finally, we study the computation of the lossy JSCC error exponent under the Hamming distortion measure.
The necessity and sufficiency of anytime capacity for stabilization of a linear system over a noisy communication link Part I: scalar systems
Venue: arXiv cs.IT 2006
Year: 2006

We review how Shannon's classical notion of capacity is not enough to characterize a noisy communication channel if the channel is intended to be used as part of a feedback loop to stabilize an unstable scalar linear system. While classical capacity is not enough, another sense of capacity (parametrized by reliability) called ``anytime capacity'' is shown to be necessary for the stabilization of an unstable process. The required rate is given by the log of the unstable system gain and the required reliability comes from the sense of stability desired. A consequence of this necessity result is a sequential generalization of the Schalkwijk/Kailath scheme for communication over the AWGN channel with feedback. In cases of sufficiently rich information patterns between the encoder and decoder, adequate anytime capacity is also shown to be sufficient for there to exist a stabilizing controller. These sufficiency results are then generalized to cases with noisy observations, delayed control actions, and without any explicit feedback between the observer and the controller. Both necessary and sufficient conditions are extended to continuous time systems as well. We close with comments discussing a hierarchy of difficulty for communication problems and how these results establish where stabilization problems sit in that hierarchy.
A Hierarchical Analysis of Propositional Temporal Logic Based on Intervals
Venue: arXiv cs.LO 2006
Year: 2006

We present a hierarchical framework for analysing propositional linear-time temporal logic (PTL) to obtain standard results such as a small model property, decision procedures and axiomatic completeness. Both finite time and infinite time are considered and one consequent benefit of the framework is the ability to systematically reduce infinite-time reasoning to finite-time reasoning. The treatment of PTL with both the operator Until and past time naturally reduces to that for PTL without either one. Our method utilises a low-level normal form for PTL called a "transition configuration". In addition, we employ reasoning about intervals of time. Besides being hierarchical and interval-based, the approach differs from other analyses of PTL typically based on sets of formulas and sequences of such sets. Instead we describe models using time intervals represented as finite and infinite sequences of states. The analysis relates larger intervals with smaller ones. Steps involved are expressed in Propositional Interval Temporal Logic (PITL) which is better suited than PTL for sequentially combining and decomposing formulas. Consequently, we can articulate issues in PTL model construction of equal relevance in more conventional analyses but normally only considered at the metalevel. We also describe a decision procedure based on Binary Decision Diagrams.
Prop-Based Haptic Interaction with Co-location and Immersion: an Automotive Application
Venue: arXiv cs.HC 2006
Year: 2006

Most research on 3D user interfaces aims at providing only a single sensory modality. One challenge is to integrate several sensory modalities into a seamless system while preserving each modality's immersion and performance factors. This paper concerns manipulation tasks and proposes a visuo-haptic system integrating immersive visualization, tactile force and tactile feedback with co-location. An industrial application is presented.
Algebraic Structures and Algorithms for Matching and Matroid Problems (Preliminary Version)
Venue: arXiv cs.DS 2006
Year: 2006

Basic path-matchings, introduced by Cunningham and Geelen (FOCS 1996), are a common generalization of matroid intersection and non-bipartite matching. The main results of this paper are a new algebraic characterization of basic path-matching problems and an algorithm for constructing basic path-matchings in O(n^w) time, where n is the number of vertices and w is the exponent for matrix multiplication. Our algorithms are randomized, and our approach assumes that the given matroids are linear and can be represented over the same field. Our main results have interesting consequences for several special cases of path-matching problems. For matroid intersection, we obtain an algorithm with running time O(nr^(w-1))=O(nr^1.38), where the matroids have n elements and rank r. This improves the long-standing bound of O(nr^1.62) due to Gabow and Xu (FOCS 1989). Also, we obtain a simple, purely algebraic algorithm for non-bipartite matching with running time O(n^w). This resolves the central open problem of Mucha and Sankowski (FOCS 2004).
Superimposed Coded and Uncoded Transmissions of a Gaussian Source over the Gaussian Channel
Venue: arXiv cs.IT 2006
Year: 2006

We propose to send a Gaussian source over an average-power limited additive white Gaussian noise channel by transmitting a linear combination of the source sequence and the result of its quantization using a high dimensional Gaussian vector quantizer. We show that, irrespective of the rate of the vector quantizer (assumed to be fixed and smaller than the channel's capacity), this transmission scheme is asymptotically optimal (as the quantizer's dimension tends to infinity) under the mean squared-error fidelity criterion. This generalizes the classical result of Goblick about the optimality of scaled uncoded transmission, which corresponds to choosing the rate of the vector quantizer as zero, and the classical source-channel separation approach, which corresponds to choosing the rate of the vector quantizer arbitrarily close to the capacity of the channel.
Using First-Order Logic to Reason about Policies
Venue: arXiv cs.LO 2006
Year: 2006

A policy describes the conditions under which an action is permitted or forbidden. We show that a fragment of (multi-sorted) first-order logic can be used to represent and reason about policies. Because we use first-order logic, policies have a clear syntax and semantics. We show that further restricting the fragment results in a language that is still quite expressive yet is also tractable. More precisely, questions about entailment, such as `May Alice access the file?', can be answered in time that is a low-order polynomial (indeed, almost linear in some cases), as can questions about the consistency of policy sets.