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New results about impartial solitaire clobber

Eric Duchêne, Sylvain Gravier, Julien Moncel (2009)

RAIRO - Operations Research

Impartial Solitaire Clobber is a one-player version of the combinatorial game Clobber, introduced by Albert et al. in 2002. The initial configuration of Impartial Solitaire Clobber is a graph, such that there is a stone placed on each of its vertex, each stone being black or white. A move of the game consists in picking a stone, and clobbering an adjacent stone of the opposite color. By clobbering we mean that the clobbered stone is removed from the graph, and replaced by the clobbering one....

New sufficient conditions for hamiltonian and pancyclic graphs

Ingo Schiermeyer, Mariusz Woźniak (2007)

Discussiones Mathematicae Graph Theory

For a graph G of order n we consider the unique partition of its vertex set V(G) = A ∪ B with A = {v ∈ V(G): d(v) ≥ n/2} and B = {v ∈ V(G):d(v) < n/2}. Imposing conditions on the vertices of the set B we obtain new sufficient conditions for hamiltonian and pancyclic graphs.

New Upper Bound for the Edge Folkman Number Fe(3,5;13)

Kolev, Nikolay (2008)

Serdica Mathematical Journal

2000 Mathematics Subject Classification: 05C55.For a given graph G let V(G) and E(G) denote the vertex and the edge set of G respevtively. The symbol G e → (a1, …, ar) means that in every r-coloring of E(G) there exists a monochromatic ai-clique of color i for some i ∈ {1,…,r}. The edge Folkman numbers are defined by the equality Fe(a1, …, ar; q) = min{|V(G)| : G e → (a1, …, ar; q) and cl(G) < q}. In this paper we prove a new upper bound on the edge Folkman number Fe(3,5;13), namely Fe(3,5;13)...

n-Functional digraphs uniquely determined by the skeleton

Konrad Pióro (2002)

Colloquium Mathematicae

We show that any total n-functional digraph D is uniquely determined by its skeleton up to the orientation of some cycles and infinite chains. Next, we characterize all graphs G such that each n-functional digraph obtained from G by directing all its edges is total. Finally, we describe finite graphs whose edges can be directed to form a total n-functional digraph without cycles.

n-functionality of graphs

Konrad Pióro (2001)

Colloquium Mathematicae

We first characterize in a simple combinatorial way all finite graphs whose edges can be directed to form an n-functional digraph, for a fixed positive integer n. Next, we prove that the possibility of directing the edges of an infinite graph to form an n-functional digraph depends on its finite subgraphs only. These results generalize Ore's result for functional digraphs.

Niche Hypergraphs

Christian Garske, Martin Sonntag, Hanns-Martin Teichert (2016)

Discussiones Mathematicae Graph Theory

If D = (V,A) is a digraph, its niche hypergraph NH(D) = (V, E) has the edge set ℇ = {e ⊆ V | |e| ≥ 2 ∧ ∃ v ∈ V : e = N−D(v) ∨ e = N+D(v)}. Niche hypergraphs generalize the well-known niche graphs (see [11]) and are closely related to competition hypergraphs (see [40]) as well as double competition hypergraphs (see [33]). We present several properties of niche hypergraphs of acyclic digraphs.

Node assignment problem in Bayesian networks

Joanna Polanska, Damian Borys, Andrzej Polanski (2006)

International Journal of Applied Mathematics and Computer Science

This paper deals with the problem of searching for the best assignments of random variables to nodes in a Bayesian network (BN) with a given topology. Likelihood functions for the studied BNs are formulated, methods for their maximization are described and, finally, the results of a study concerning the reliability of revealing BNs' roles are reported. The results of BN node assignments can be applied to problems of the analysis of gene expression profiles.

Nombre maximum d’ordres de Slater des tournois T vérifiant σ ( T ) = 1

Olivier Hudry (1997)

Mathématiques et Sciences Humaines

On s’intéresse ici au nombre maximum d’ordres de Slater qu’admettent les tournois T vérifiant σ ( T ) = 1 , où σ ( T ) est un paramètre calculé à partir des scores de T . On détermine ce nombre maximum d’ordres de Slater, de l’ordre de 2 n / 2 , si n désigne le nombre de sommets. On donne de plus la forme des tournois T vérifiant σ ( T ) = 1 et maximisant le nombre d’ordres de Slater. En particulier, on obtient que ces tournois ne sont pas fortement connexes pour n pair.

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