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Implementation of directed acyclic word graph

Miroslav Balík (2002)

Kybernetika

An effective implementation of a Directed Acyclic Word Graph (DAWG) automaton is shown. A DAWG for a text T is a minimal automaton that accepts all substrings of a text T , so it represents a complete index of the text. While all usual implementations of DAWG needed about 30 times larger storage space than was the size of the text, here we show an implementation that decreases this requirement down to four times the size of the text. The method uses a compression of DAWG elements, i. e. vertices,...

Improved Sufficient Conditions for Hamiltonian Properties

Jens-P. Bode, Anika Fricke, Arnfried Kemnitz (2015)

Discussiones Mathematicae Graph Theory

In 1980 Bondy [2] proved that a (k+s)-connected graph of order n ≥ 3 is traceable (s = −1) or Hamiltonian (s = 0) or Hamiltonian-connected (s = 1) if the degree sum of every set of k+1 pairwise nonadjacent vertices is at least ((k+1)(n+s−1)+1)/2. It is shown in [1] that one can allow exceptional (k+ 1)-sets violating this condition and still implying the considered Hamiltonian property. In this note we generalize this result for s = −1 and s = 0 and graphs that fulfill a certain connectivity condition....

Improved upper bounds for nearly antipodal chromatic number of paths

Yu-Fa Shen, Guo-Ping Zheng, Wen-Jie HeK (2007)

Discussiones Mathematicae Graph Theory

For paths Pₙ, G. Chartrand, L. Nebeský and P. Zhang showed that a c ' ( P ) n - 2 2 + 2 for every positive integer n, where ac’(Pₙ) denotes the nearly antipodal chromatic number of Pₙ. In this paper we show that a c ' ( P ) n - 2 2 - n / 2 - 10 / n + 7 if n is even positive integer and n ≥ 10, and a c ' ( P ) n - 2 2 - ( n - 1 ) / 2 - 13 / n + 8 if n is odd positive integer and n ≥ 13. For all even positive integers n ≥ 10 and all odd positive integers n ≥ 13, these results improve the upper bounds for nearly antipodal chromatic number of Pₙ.

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