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On the matrices of central linear mappings

Hans Havlicek (1996)

Mathematica Bohemica

We show that a central linear mapping of a projectively embedded Euclidean n -space onto a projectively embedded Euclidean m -space is decomposable into a central projection followed by a similarity if, and only if, the least singular value of a certain matrix has multiplicity 2 m - n + 1 . This matrix is arising, by a simple manipulation, from a matrix describing the given mapping in terms of homogeneous Cartesian coordinates.

On the median-of-k version of Hoare's selection algorithm

Rudolf Grübel (2010)

RAIRO - Theoretical Informatics and Applications

In Hoare's (1961) original version of the algorithm   the partitioning element in the central divide-and-conquer step is chosen uniformly at random from the set S in question. Here we consider a variant where this element is the median of a sample of size 2k+1 from S. We investigate convergence in distribution of the number of comparisons required and obtain a simple explicit result for the limiting average performance of the median-of-three version.

On the M/G/1 retrial queue subjected to breakdowns

Natalia V. Djellab (2002)

RAIRO - Operations Research - Recherche Opérationnelle

Retrial queueing systems are characterized by the requirement that customers finding the service area busy must join the retrial group and reapply for service at random intervals. This paper deals with the M/G/1 retrial queue subjected to breakdowns. We use its stochastic decomposition property to approximate the model performance in the case of general retrial times.

On the M/G/1 retrial queue subjected to breakdowns

Natalia V. Djellab (2010)

RAIRO - Operations Research

Retrial queueing systems are characterized by the requirement that customers finding the service area busy must join the retrial group and reapply for service at random intervals. This paper deals with the M/G/1 retrial queue subjected to breakdowns. We use its stochastic decomposition property to approximate the model performance in the case of general retrial times.

On the number of binary signed digit representations of a given weight

Jiří Tůma, Jiří Vábek (2015)

Commentationes Mathematicae Universitatis Carolinae

Binary signed digit representations (BSDR’s) of integers have been studied since the 1950’s. Their study was originally motivated by multiplication and division algorithms for integers and later by arithmetics on elliptic curves. Our paper is motivated by differential cryptanalysis of hash functions. We give an upper bound for the number of BSDR’s of a given weight. Our result improves the upper bound on the number of BSDR’s with minimal weight stated by Grabner and Heuberger in On the number of...

On the number of iterations required by Von Neumann addition

Rudolf Grübel, Anke Reimers (2001)

RAIRO - Theoretical Informatics and Applications - Informatique Théorique et Applications

We investigate the number of iterations needed by an addition algorithm due to Burks et al. if the input is random. Several authors have obtained results on the average case behaviour, mainly using analytic techniques based on generating functions. Here we take a more probabilistic view which leads to a limit theorem for the distribution of the random number of steps required by the algorithm and also helps to explain the limiting logarithmic periodicity as a simple discretization phenomenon.

On the number of iterations required by Von Neumann addition

Rudolf Grübel, Anke Reimers (2010)

RAIRO - Theoretical Informatics and Applications

We investigate the number of iterations needed by an addition algorithm due to Burks et al. if the input is random. Several authors have obtained results on the average case behaviour, mainly using analytic techniques based on generating functions. Here we take a more probabilistic view which leads to a limit theorem for the distribution of the random number of steps required by the algorithm and also helps to explain the limiting logarithmic periodicity as a simple discretization phenomenon.

On the Number of Partitions of an Integer in the m -bonacci Base

Marcia Edson, Luca Q. Zamboni (2006)

Annales de l’institut Fourier

For each m 2 , we consider the m -bonacci numbers defined by F k = 2 k for 0 k m - 1 and F k = F k - 1 + F k - 2 + + F k - m for k m . When m = 2 , these are the usual Fibonacci numbers. Every positive integer n may be expressed as a sum of distinct m -bonacci numbers in one or more different ways. Let R m ( n ) be the number of partitions of n as a sum of distinct m -bonacci numbers. Using a theorem of Fine and Wilf, we obtain a formula for R m ( n ) involving sums of binomial coefficients modulo 2 . In addition we show that this formula may be used to determine the number of partitions...

On the number of squares in partial words

Vesa Halava, Tero Harju, Tomi Kärki (2010)

RAIRO - Theoretical Informatics and Applications

The theorem of Fraenkel and Simpson states that the maximum number of distinct squares that a word w of length n can contain is less than 2n. This is based on the fact that no more than two squares can have their last occurrences starting at the same position. In this paper we show that the maximum number of the last occurrences of squares per position in a partial word containing one hole is 2k, where k is the size of the alphabet. Moreover, we prove that the number of distinct squares in a partial...

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