نتایج جستجو برای: perfect human being

تعداد نتایج: 2174787  

2008
Matthew Clarke Mark McGillivray

Journal: :J. Comb. Theory, Ser. B 2009
Maria Chudnovsky Paul D. Seymour

Our proof (with Robertson and Thomas) of the strong perfect graph conjecture ran to 179 pages of dense matter; and the most impenetrable part was the final 55 pages, on what we called “wheel systems”. In this paper we give a replacement for those 55 pages, much easier and shorter, using “even pairs”. This is based on an approach of Maffray and Trotignon.

Journal: :Des. Codes Cryptography 1994
Chris J. Mitchell

A c-ary Perfect Factor is a set of uniformly long cycles whose elements are drawn from a set of size c, in which every possible v-tuple of elements occurs exactly once. In the binary case, i.e. where c = 2, these perfect factors have previously been studied by Etzion, [2], who showed that the obvious necessary conditions for their existence are in fact sufficient. This result has recently been ...

Journal: :Discussiones Mathematicae Graph Theory 2000
Van Bang Le

The complement of a graph G is denoted by G. χ(G) denotes the chromatic number and ω(G) the clique number of G. The cycles of odd length at least five are called odd holes and the complements of odd holes are called odd anti-holes. A graph G is called perfect if, for each induced subgraph G of G, χ(G) = ω(G). Classical examples of perfect graphs consist of bipartite graphs, chordal graphs and c...

Journal: :Discrete Mathematics 2009
Florian Roussel Irena Rusu Henri Thuillier

The Strong Perfect Graph Conjecture (SPGC) was certainly one of the most challenging conjectures in graph theory. During more than four decades, numerous attempts were made to solve it, by combinatorial methods, by linear algebraic methods, or by polyhedral methods. The rst of these three approaches yielded the rst (and to date only) proof of the SPGC; the other two remain promising to consider...

Journal: :Graphs and Combinatorics 2007
Vincent Jost Benjamin Lévêque Frédéric Maffray

The pre-coloring extension problem consists, given a graph G and a subset of nodes to which some colors are already assigned, in finding a coloring of G with the minimum number of colors which respects the pre-coloring assignment. This can be reduced to the usual coloring problem on a certain contracted graph. We prove that pre-coloring extension is polynomial for complements of Meyniel graphs....

2008
SETH SULLIVANT

The construction of joins and secant varieties is studied in the combinatorial context of monomial ideals. For ideals generated by quadratic monomials, the generators of the secant ideals are obstructions to graph colorings, and this leads to a commutative algebra version of the Strong Perfect Graph Theorem. Given any projective variety and any term order, we explore whether the initial ideal o...

Journal: :CoRR 2005
Vincent Jost Benjamin Lévêque Frédéric Maffray

The pre-coloring extension problem consists, given a graph G and a subset of nodes to which some colors are already assigned, in nding a coloring of G with the minimum number of colors which respects the pre-coloring assignment. This can be reduced to the usual coloring problem on a certain contracted graph. We prove that pre-coloring extension is polynomial for complements of Meyniel graphs. W...

ژورنال: مطالعات تفسیری 2019

Hakim Dashtaki has viewed human being as spacio-temporal being and future etrnal but not past eternal. He has proved the view by relying on the verse: Hath there come Upon man (ever) any period of time in which he was a thing unremembered? Ibn Arabi, however, views human being as both past eternal and future eternal. The article has intended to study some commenators` opinions of the verse and ...

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