Various Fields Of Computer Science Research Articles

Pseudorandom generators against advised context-free languages

Pseudorandomness has played a central role in modern cryptography, finding theoretical and practical applications to various fields of computer science. A function that generates pseudorandom strings from shorter but truly random seeds is known as a pseudorandom generator. Our generators are designed to fool languages (or equivalently, Boolean-valued functions). In particular, our generator fools advised context-free languages, namely, context-free languages assisted by external information known as advice, and moreover our generator is made almost one-to-one, stretching n-bit seeds to n+1 bits. We explicitly construct such a pseudorandom generator, which is computed by a deterministic Turing machine using logarithmic space and also belongs to CFLMV(2)/n—a functional extension of the 2-conjunctive closure of CFL with the help of appropriate deterministic advice. In contrast, we show that there is no almost one-to-one pseudorandom generator against context-free languages if we demand that it should be computed by a nondeterministic pushdown automaton equipped with a write-only output tape. Our generator naturally extends known pseudorandom generators against advised regular languages. Our proof of the CFL/n-pseudorandomness of the generator is quite elementary and, in particular, one part of the proof utilizes a special feature of the behaviors of nondeterministic pushdown automata, called a swapping property, which is interesting in its own right, generalizing the swapping lemma for context-free languages.

On application of bloom filters to iris biometrics

In this study, the application of adaptive Bloom filters to binary iris biometric feature vectors, that is, iris-codes, is proposed. Bloom filters, which have been established as a powerful tool in various fields of computer science, are applied in order to transform iris-codes to a rotation-invariant feature representation. Properties of the proposed Bloom filter-based transform concurrently enable (i) biometric template protection, (ii) compression of biometric data and (iii) acceleration of biometric identification, whereas at the same time no significant degradation of biometric performance is observed. According to these fields of application, detailed investigations are presented. Experiments are conducted on the CASIA-v3 iris database for different feature extraction algorithms. Confirming the soundness of the proposed approach, the application of adaptive Bloom filters achieves rotation-invariant cancellable templates maintaining biometric performance, a compression of templates down to 20-40% of original size and a reduction of bit-comparisons to less than 5% leading to a substantial speed-up of the biometric system in identification mode.

Increasing the Efficiency of Image Results through Improved Image retrieval by using Image Mining in Search Engines

With the growth of Internet and advances in storage technologies, spread and acquisition of images has become imperative. Despite unprecedented advances in data mining, search engines return results of image queries by mining the written text associated with the images rather than mining the images to provide suitable results as per the image query. Image mining isn't merely an extension of data mining to image domain. It is an interdisciplinary attempt that draws upon expertise in various fields of Computer Science, ranging from computer vision, image processing and image retrieval to data mining, machine learning, database, and artificial intelligence. In this paper, we will suggest how image mining can be successfully implemented and will also suggest possible future research in the said discipline.

Interdisziplinarität als Herausforderung für die E-Learning-Forschung

Summary Research in e-learning requires collaboration within the various fields of computer science as well as between computer scientists and a variety of other disciplines. The article lists important prerequisites and challenges of interdisciplinary collaboration.

Formal systems for persuasion dialogue

This article reviews formal systems that regulate persuasion dialogues. In such dialogues two or more participants aim to resolve a difference of opinion, each trying to persuade the other participants to adopt their point of view. Systems for persuasion dialogue have found application in various fields of computer science, such as non-monotonic logic, artificial intelligence and law, multi-agent systems, intelligent tutoring and computer-supported collaborative argumentation. Taking a game-theoretic view on dialogue systems, this review proposes a formal specification of the main elements of dialogue systems for persuasion and then uses it to critically review some of the main formal systems for persuasion. The focus of this review will be on regulating the interaction between agents rather than on the design and behaviour of individual agents within a dialogue.

Barcelona, Spain, October 7-8, 2002: Graph-Based Tools (GraBaTs 2002)

Barcelona, Spain, October 7-8, 2002: Graph-Based Tools (GraBaTs 2002)

Highly regular, modular, and cascadable design of cellular automata-based pattern classifier

This paper enumerates a new approach to the solution of classification problems based on the properties of Additive Cellular Automata. Classification problem plays a major role in various fields of computer science, such as grouping of the records in database systems, detection of faults in VLSI circuits, image processing, and so on. The state-transition graph of Non-group Cellular Automata (CA) consists of a set of disjoint trees rooted at some cyclic states of unit cycle length - thus forming a natural classifier. First a scheme of classifying the patterns distributed into only two classes has been dealt with. This has been further extended for solution of the multiclass classification problem. The Multiclass Classifier saves on an average 34% of memory as compared to the straight-forward approach storing directly the class of each pattern. A regular, modular, and cascadable hardware implementation of the classifier has been presented which is highly suitable for VLSI realization. The design has been specified in Verilog and verified for functional correctness.

ZIPF'S LAWS IN TEXT MODELING

Abstract Zipf's first and second laws define two striking phenomena in literary text. The two laws have applications in various fields of computer science. Recently, the study of continuous speech recognition in artificial intelligence has called for the use of statistical models of text generation. A major issue is the lack of effective and objective evaluation of the models. In this paper, four leading statistical models of text generation are evaluated with respect to Zipf's laws and we identify the Simon-Yule model as a promising approach. A significant implication of the findings for text modeling is also discussed.

Generating cartesian products of two sets on a shuffle‐exchange network

AbstractThis paper describes a method which generates all elements of a Cartesian product of two sets, using the shuffle‐exchange network. Often, processing appears which requires all elements of the Cartesian product in various fields in computer science as well as set manipulations in mathematics. Consequently, this operation can be considered to be one of the most fundamental. In this paper, the Cartesian product of two sets with N/2 elements is generated by an N‐input, N/2‐stage shuffle‐exchange network by assigning the switching element to each element of the Cartesian product. The experimental derivation of the realization method and the result of the experiment are described. In the derivation of the realization method, some properties of the shuffle‐exchange network are discussed. In the realization of the Cartesian product by an N/2‐stage shuffle‐exchange network, no redundant switching element is used. Consequently, the method shown in this paper is optimal.

A prototype of an intelligent system for information retrieval: IOTA

Recent results in artificial intelligence research are of prime interest in various fields of computer science; in particular we think information retrieval may benefit from significant advances in this approach. Expert systems seem to be valuable tools for components of information retrieval systems related to semantic inference. The query component is the one we consider in this paper. IOTA is the name of the resulting prototype presented here, which is our first step toward what we call an intelligent system for information retrieval. After explaining what we mean by this concept and presenting current studies in the field, the presentation of IOTA begins with the architecture problem, that is, how to put together a declarative component, such as an expert system, and a procedural component, such as an information retrieval system. Then we detail our proposed solution, which is based on a procedural expert system acting as the general scheduler of the entire query processing. The main steps of natural language query processing are then described according to the order in which they are processed, from the initial parsing of the query to the evaluation of the answer. The distinction between expert tasks and nonexpert tasks is emphasized. The paper ends with experimental results obtained from a technical corpus, and a conclusion about current and future developments.

The direction the FGCS Project will take

The nature of Japan’s Fifth Generation Computer Systems Project is discussed. Aimed at the accomplishment of basic research for innovation in future computer technology, the project itself has no commercial objectives. Logic programming is envisioned as the missing link unifying the various fields of computer science and is thus emphasized. Logic is emphasized in the approach to knowledge engineering, as is the need for radically more powerful computer tools for research on artificial intelligence. Logic is also stressed as the key to developing parallel architecture.

Parallelism and concurrency of graph manipulations

Graph manipulations are formalized as graph derivations within the framework of graph grammar theory. In this paper we generalize recently published ‘Church–Rosser’ and ‘Parallelism’ Theorems for graph derivations. Given a ‘sequential independent’ sequence of graph derivations G⇒ H ⇒ X the Parallelism Theorem states that there is also a sequential independent sequence via the same productions applied in reverse order, and a direct derivation G ⇒ X via the corresponding parallel production. In our ‘Concurrency Theorem’, the main result of this paper, the assumption of sequential independence is dropped. For each sequence of productions together with dependence relations (allowing later rules to depend on the effects of earlier productions), we construct a single ‘concurrent production’. The Concurrency Theorem states that each graph derivation sequence via the given sequence of productions, which respects all the dependence relations, can be performed in a single direct derivation via the ‘concurrent production’. Moreover this assignment becomes a bijective correspondence. This Concurrency Theorem is formulated and proved in the framework of the algebraic theory of graph grammars using new pushout and pullback lemmas for the 3- and 4- dimensional cubes. As corollaries we obtain the Parallelism Theorem and a theorem reducing the strong to the weak Church–Rosser-property of graph derivations. Applications of these results to various fields in computer science especially to data base systems, are sketched in the introduction.