16 resultados para Error-correcting codes (Information theory)

em Bulgarian Digital Mathematics Library at IMI-BAS


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The emergence of digital imaging and of digital networks has made duplication of original artwork easier. Watermarking techniques, also referred to as digital signature, sign images by introducing changes that are imperceptible to the human eye but easily recoverable by a computer program. Usage of error correcting codes is one of the good choices in order to correct possible errors when extracting the signature. In this paper, we present a scheme of error correction based on a combination of Reed-Solomon codes and another optimal linear code as inner code. We have investigated the strength of the noise that this scheme is steady to for a fixed capacity of the image and various lengths of the signature. Finally, we compare our results with other error correcting techniques that are used in watermarking. We have also created a computer program for image watermarking that uses the newly presented scheme for error correction.

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In this work, we determine the coset weight spectra of all binary cyclic codes of lengths up to 33, ternary cyclic and negacyclic codes of lengths up to 20 and of some binary linear codes of lengths up to 33 which are distance-optimal, by using some of the algebraic properties of the codes and a computer assisted search. Having these weight spectra the monotony of the function of the undetected error probability after t-error correction P(t)ue (C,p) could be checked with any precision for a linear time. We have used a programm written in Maple to check the monotony of P(t)ue (C,p) for the investigated codes for a finite set of points of p € [0, p/(q-1)] and in this way to determine which of them are not proper.

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2000 Mathematics Subject Classification: 94A29, 94B70

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* Supported by COMBSTRU Research Training Network HPRN-CT-2002-00278 and the Bulgarian National Science Foundation under Grant MM-1304/03.

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The basic structure of the General Information Theory (GIT) is presented in the paper. The main divisions of the GIT are outlined. Some new results are pointed.

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In 1965 Levenshtein introduced the deletion correcting codes and found an asymptotically optimal family of 1-deletion correcting codes. During the years there has been a little or no research on t-deletion correcting codes for larger values of t. In this paper, we consider the problem of finding the maximal cardinality L2(n;t) of a binary t-deletion correcting code of length n. We construct an infinite family of binary t-deletion correcting codes. By computer search, we construct t-deletion codes for t = 2;3;4;5 with lengths n ≤ 30. Some of these codes improve on earlier results by Hirschberg-Fereira and Swart-Fereira. Finally, we prove a recursive upper bound on L2(n;t) which is asymptotically worse than the best known bounds, but gives better estimates for small values of n.

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The current formal as well as not formal definitions of the concept "Information” are presented in the paper.

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This paper presents an extended behavior of networks of evolutionary processors. Usually, such nets are able to solve NP-complete problems working with symbolic information. Information can evolve applying rules and can be communicated though the net provided some constraints are verified. These nets are based on biological behavior of membrane systems, but transformed into a suitable computational model. Only symbolic information is communicated. This paper proposes to communicate evolution rules as well as symbolic information. This idea arises from the DNA structure in living cells, such DNA codes information and operations and it can be sent to other cells. Extended nets could be considered as a superset of networks of evolutionary processors since permitting and forbidden constraints can be written in order to deny rules communication.

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The adequate attitude to the information models and information objects in the culture context is one of the main problems to be investigated on the threshold of information society. The goal of this paper is to outline some problems connected with the main styles of perceiving of the mental and artificially generated information models stored in the information objects and used in the processes of the Information Interaction or simply – in the Inforaction. The culture influence on inforaction is discussed.

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In this paper, the “Information Market” is introduced as a payable information exchange and based on it information interaction. In addition, special kind of Information Markets - the Knowledge Markets are outlined. The main focus of the paper is concentrated on the investigation of the staple commodities of the knowledge markets. They are introduced as kind of information objects, called “knowledge information objects”. The main theirs distinctive characteristic is that they contain information models, which concern sets of information models and interconnections between them.

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The concept INFOS is very important for understanding the information phenomena. Because of this, it is basic for the General Information Theory. The more precise formal definition of this concept is given in the paper.

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Определение многокритериального решения по своей природе компромиссно и принципиально основано на использовании субъективной информации. Возможность решения проблемы основана на гипотезе существования некоторой функции полезности. Традиционный подход линеаризации функции полезности обладает многими недостатками. Предлагается концепция нелинейной схемы компромиссов.

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Рассматриваются проблемы коллективного выбора. Обсуждаются преимущества и недостатки коллективного выбора, различные подходы для решения этих задач. Предлагается подход, позволяющие использовать аппарат нечеткой логики для моделирования задач коллективного выбора.

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A definition of the concept "business informatics" based on the General Information Theory is discussed in the paper.

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Предлагаются методы автоматической классификации и моделирования генетического кода. Излагаются принципы проектирования и результаты использования гетерогенных генно- нейронных сетей.