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Kinga MARTON, Alin SUCIU, Iosif IGNAT
Randomness in Digital Cryptography: A Survey
pp. 219–240

Abstract. Digital cryptography relies greatly on randomness in providing the security requirements imposed by various information systems. Just as different requirements call for specific cryptographic techniques, randomness takes upon a variety of roles in order to ensure the proper strength of these cryptographic primitives. The purpose of the survey is to emphasize the importance of randomness in digital cryptography by identifying and highlighting the many roles random number sequences play and to carry forth the significance of choosing and integrating suitable random number generators as security flaws in the generator can easily compromise the security of the whole system. Read the pdf

 

 

 

 

 

 

 

 

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Claudiu-Florin GIURGIU
An implementation of the backtracking algorithm for multicore systems
pp. 241–254

Abstract. The emergence of inexpensive parallel computers powered by multicore chips combined with high clock rates raises new challenges for software engineering. Since the performance improvements will not come from increased clock rates, high performance applications will need to be parallelized. In addition to operating system support, adjustments to existing software are required to maximize utilization of the computing resources provided by multicore processors. The ability of multicore processors to increase application performance depends on the use of multiple threads within applications. We will describe an algorithm that allows backtracking problems to be solved by means of such multicore systems. A multicore algorithm meant for backtracking problems and able to meet certain constraints is made of multiple search threads with concurrent operation and distinct processing parts of the solution space. The proposed algorithm is scalable. Read the pdf

 

 

 

 

 

 

 

 

 

 

 

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Daniel Claudian VOINESCU
Elementary Alphabets of a Language
pp. 255–278

Abstract. The paper pertains to the field of Combinatorics on words. We introduce the notion of elementary alphabet of a language as the natural generalization of the combinatorial alphabet introduced in [10]. By analogy with the famous Ehrenfeucht conjecture, we prove a compactness property of all words in a language, namely, that any language has a finite elementary test-set. Then we show that the class of all elementary sets of a regular language can be effectively constructed. As a consequence, it is decidable whether a given finite part of a regular language is an elementary test-set for that language. Read the pdf

 

 

 

 

 

 

 

 

 

 

 

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Katalin Anna LAZAR, Erzsebet Csuhaj–VARJU, Andras LORINCZ
On EcoForaging Systems
pp. 279–309

Abstract. In this paper we present a formal language theoretic approach to Internet crawlers seeking novel information on the World Wide Web, based on a modified version of eco–grammar systems, called eco–foraging systems. In our model, the grammars correspond to very simple autonomous agents and the generated language to the behaviour of the system. In fact, the agents are represented by regulated rewriting devices, which impose some constraint on the search strategy of the agent. The letters of the generated strings symbolize the web pages. We prove that if we ignore the aging of the web environment in the model, then through the simulation of certain normal form grammars, the eco–foraging systems determine the class of recursively enumerable languages. If the web pages may become obsolete, then the language family generated by unordered scattered context grammars of finite index can be obtained. The ignorance of lifetime implies that the crawlers communicating only through the environment are able to identify any computable set of the environmental states. The lifetime constraint, however, considerably decreases the efficiency of the cooperation of the agents. Read the pdf.

 

 

 

 

 

 

 

 

 

 

 

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Dragos BURILEANU, Mihai SURMEI, Cristian NEGRESCU, Catalin UNGUREAN, Aurelian DERVIS
Multi-Access Network-Based TTS Architectures
pp. 310–320

Abstract. There are many areas were text-to-speech (TTS) synthesis could enhance the end-user experience or even change the behavior of using existing network services starting from simple notification applications to complex presence enabled instant messaging convergent services. For this to happen we may need to bring TTS service in the multi-access area of Internet Multimedia Subsystem (IMS) networks and implement network-based TTS architectures. This paper proposes a pre-IMS network architecture leveraging a Romanian TTS system and a reference framework for developing future convergent network services around TTS technology. Read the pdf.