Displaying similar documents to “Rewriting on cyclic structures: Equivalence between the operational and the categorical description”

A note on maximum independent sets and minimum clique partitions in unit disk graphs and penny graphs: complexity and approximation

Marcia R. Cerioli, Luerbio Faria, Talita O. Ferreira, Fábio Protti (2011)

RAIRO - Theoretical Informatics and Applications - Informatique Théorique et Applications

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A is the intersection graph of a family of unit disks in the plane. If the disks do not overlap, it is also a or . It is known that finding a maximum independent set in a unit disk graph is a NP-hard problem. In this work we extend this result to penny graphs. Furthermore, we prove that finding a minimum clique partition in a penny graph is also NP-hard, and present two linear-time approximation algorithms for the computation of clique partitions: a -approximation algorithm for unit...

A note on maximum independent sets and minimum clique partitions in unit disk graphs and penny graphs: complexity and approximation

Marcia R. Cerioli, Luerbio Faria, Talita O. Ferreira, Fábio Protti (2011)

RAIRO - Theoretical Informatics and Applications

Similarity:

A is the intersection graph of a family of unit disks in the plane. If the disks do not overlap, it is also a or . It is known that finding a maximum independent set in a unit disk graph is a NP-hard problem. In this work we extend this result to penny graphs. Furthermore, we prove that finding a minimum clique partition in a penny graph is also NP-hard, and present two linear-time approximation algorithms for the computation of clique partitions: a -approximation algorithm for unit...

Comparing Imperfection Ratio and Imperfection Index for Graph Classes

Arie M.C.A. Koster, Annegret K. Wagler (2009)

RAIRO - Operations Research

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Perfect graphs constitute a well-studied graph class with a rich structure, reflected by many characterizations with respect to different concepts. Perfect graphs are, for instance, precisely those graphs where the stable set polytope STAB() coincides with the fractional stable set polytope QSTAB(). For all imperfect graphs it holds that STAB() ⊂ QSTAB(). It is, therefore, natural to use the difference between the two polytopes in order to decide how far an imperfect graph...

Minimum convex-cost tension problems on series-parallel graphs

Bruno Bachelet, Philippe Mahey (2010)

RAIRO - Operations Research

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We present briefly some results we obtained with known methods to solve minimum cost tension problems, comparing their performance on non-specific graphs and on series-parallel graphs. These graphs are shown to be of interest to approximate many tension problems, like synchronization in hypermedia documents. We propose a new method to solve the minimum convex piecewise linear cost tension problem on series-parallel graphs in operations.