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On spectral bandwidth of a stationary random process

Vladimír Klega (1983)

Aplikace matematiky

The irregularity coefficient is one of the numerical characteristics of the spectral bandwith of a stationary random process. Its basic properties are investigated and the application to the dichotomic classification of a process into narrow-band and wide-band ones is given. Further, its behaviour is analyzed for sufficiently wide classes of stationary processes whose spectral densities frequently appear both in theory and applications.

On the amount of information resulting from empirical and theoretical knowledge.

Igor Vajda, Arnost Vesely, Jana Zvarova (2005)

Revista Matemática Complutense

We present a mathematical model allowing formally define the concepts of empirical and theoretical knowledge. The model consists of a finite set P of predicates and a probability space (Ω, S, P) over a finite set Ω called ontology which consists of objects ω for which the predicates π ∈ P are either valid (π(ω) = 1) or not valid (π(ω) = 0). Since this is a first step in this area, our approach is as simple as possible, but still nontrivial, as it is demonstrated by examples. More realistic approach...

On the anti–synchronization detection for the generalized Lorenz system and its applications to secure encryption

Volodymyr Lynnyk, Sergej Čelikovský (2010)

Kybernetika

In this paper, a modified version of the Chaos Shift Keying (CSK) scheme for secure encryption and decryption of data will be discussed. The classical CSK method determines the correct value of binary signal through checking which initially unsynchronized system is getting synchronized. On the contrary, the new anti-synchronization CSK (ACSK) scheme determines the wrong value of binary signal through checking which already synchronized system is loosing synchronization. The ACSK scheme is implemented...

On the Automorphism Groups of some AG-Codes Based on Ca;b Curves

Shaska, Tanush, Wang, Quanlong (2007)

Serdica Journal of Computing

*Partially supported by NATO.We study Ca,b curves and their applications to coding theory. Recently, Joyner and Ksir have suggested a decoding algorithm based on the automorphisms of the code. We show how Ca;b curves can be used to construct MDS codes and focus on some Ca;b curves with extra automorphisms, namely y^3 = x^4 + 1, y^3 = x^4 - x, y^3 - y = x^4. The automorphism groups of such codes are determined in most characteristics.

On the classification of 3-dimensional non-associative division algebras over p -adic fields

Abdulaziz Deajim, David Grant (2011)

Journal de Théorie des Nombres de Bordeaux

Let p be a prime and K a p -adic field (a finite extension of the field of p -adic numbers p ). We employ the main results in [12] and the arithmetic of elliptic curves over K to reduce the problem of classifying 3-dimensional non-associative division algebras (up to isotopy) over K to the classification of ternary cubic forms H over K (up to equivalence) with no non-trivial zeros over K . We give an explicit solution to the latter problem, which we then relate to the reduction type of the jacobian...

On the Complexity of the Hidden Weighted Bit Function for Various BDD Models

Beate Bollig, Martin Löbbing, Martin Sauerhoff, Ingo Wegener (2010)

RAIRO - Theoretical Informatics and Applications

Ordered binary decision diagrams (OBDDs) and several more general BDD models have turned out to be representations of Boolean functions which are useful in applications like verification, timing analysis, test pattern generation or combinatorial optimization. The hidden weighted bit function (HWB) is of particular interest, since it seems to be the simplest function with exponential OBDD size. The complexity of this function with respect to different circuit models, formulas, and various...

On the computation of covert channel capacity

Eugene Asarin, Cătălin Dima (2010)

RAIRO - Theoretical Informatics and Applications

We address the problem of computing the capacity of a covert channel, modeled as a nondeterministic transducer. We give three possible statements of the notion of “covert channel capacity” and relate the different definitions. We then provide several methods allowing the computation of lower and upper bounds for the capacity of a channel. We show that, in some cases, including the case of input-deterministic channels, the capacity of the channel can be computed exactly (e.g. in the form...

On the computational complexity of centers locating in a graph

Ján Plesník (1980)

Aplikace matematiky

It is shown that the problem of finding a minimum k -basis, the n -center problem, and the p -median problem are N P -complete even in the case of such communication networks as planar graphs with maximum degree 3. Moreover, a near optimal m -center problem is also N P -complete.

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