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Partial covers of graphs

Jirí Fiala, Jan Kratochvíl (2002)

Discussiones Mathematicae Graph Theory

Given graphs G and H, a mapping f:V(G) → V(H) is a homomorphism if (f(u),f(v)) is an edge of H for every edge (u,v) of G. In this paper, we initiate the study of computational complexity of locally injective homomorphisms called partial covers of graphs. We motivate the study of partial covers by showing a correspondence to generalized (2,1)-colorings of graphs, the notion stemming from a practical problem of assigning frequencies to transmitters without interference. We compare the problems of...

Paths through fixed vertices in edge-colored graphs

W. S. Chou, Y. Manoussakis, O. Megalakaki, M. Spyratos, Zs. Tuza (1994)

Mathématiques et Sciences Humaines

We study the problem of finding an alternating path having given endpoints and passing through a given set of vertices in edge-colored graphs (a path is alternating if any two consecutive edges are in different colors). In particular, we show that this problem in NP-complete for 2-edge-colored graphs. Then we give a polynomial characterization when we restrict ourselves to 2-edge-colored complete graphs. We also investigate on (s,t)-paths through fixed vertices, i.e. paths of length s+t such that...

p-Median problems in a fuzzy environment.

David Kutangila-Mayoya, José Luis Verdegay (2005)

Mathware and Soft Computing

In this paper a formulation for the fuzzy p-median model in a fuzzy environment is presented. The model allows to find optimal locations of p facilities and their related cost when data related to the node demands and the edge distances are imprecise and uncertain and also to know the degree of certainty of the solution. For the sake of illustration, the proposed model is applied in a reduced map of Kinshasa (Democratic Republic of Congo) obtaining results which are rather than realistic ones.

Porous media equation on locally finite graphs

Li Ma (2022)

Archivum Mathematicum

In this paper, we consider two typical problems on a locally finite connected graph. The first one is to study the Bochner formula for the Laplacian operator on a locally finite connected graph. The other one is to obtain global nontrivial nonnegative solution to porous-media equation via the use of Aronson-Benilan argument. We use the curvature dimension condition to give a characterization two point graph. We also give a porous-media equation criterion about stochastic completeness of the graph....

Prescribed ultrametrics

J. Higgins, D. Campbell (1993)

RAIRO - Theoretical Informatics and Applications - Informatique Théorique et Applications

Quasiperfect domination in triangular lattices

Italo J. Dejter (2009)

Discussiones Mathematicae Graph Theory

A vertex subset S of a graph G is a perfect (resp. quasiperfect) dominating set in G if each vertex v of G∖S is adjacent to only one vertex ( d v ∈ 1,2 vertices) of S. Perfect and quasiperfect dominating sets in the regular tessellation graph of Schläfli symbol 3,6 and in its toroidal quotients are investigated, yielding the classification of their perfect dominating sets and most of their quasiperfect dominating sets S with induced components of the form K ν , where ν ∈ 1,2,3 depends only on S.

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