Chiral hypermaps of small genus.
Chiral hypermaps with few hyperfaces
Circularity of graphs and continua: topology
Classification of -dipoles on nonorientable surfaces.
Classification of rings with toroidal Jacobson graph
Let be a commutative ring with nonzero identity and the Jacobson radical of . The Jacobson graph of , denoted by , is defined as the graph with vertex set such that two distinct vertices and are adjacent if and only if is not a unit of . The genus of a simple graph is the smallest nonnegative integer such that can be embedded into an orientable surface . In this paper, we investigate the genus number of the compact Riemann surface in which can be embedded and explicitly...
Clique-connecting forest and stable set polytopes
Let G = (V,E) be a simple undirected graph. A forest F ⊆ E of G is said to be clique-connecting if each tree of F spans a clique of G. This paper adresses the clique-connecting forest polytope. First we give a formulation and a polynomial time separation algorithm. Then we show that the nontrivial nondegenerate facets of the stable set polytope are facets of the clique-connecting polytope. Finally we introduce a family of rank inequalities which are facets, and which generalize the clique inequalities. ...
Clopen graphs
A graph G on a topological space X as its set of vertices is clopen if the edge relation of G is a clopen subset of X² without the diagonal. We study clopen graphs on Polish spaces in terms of their finite induced subgraphs and obtain information about their cochromatic numbers. In this context we investigate modular profinite graphs, a class of graphs obtained from finite graphs by taking inverse limits. This continues the investigation of continuous colorings on Polish spaces and their homogeneity...
Colorings and orientations of matrices and graphs.
Colouring vertices of plane graphs under restrictions given by faces
We consider a vertex colouring of a connected plane graph G. A colour c is used k times by a face α of G if it appears k times along the facial walk of α. We prove that every connected plane graph with minimum face degree at least 3 has a vertex colouring with four colours such that every face uses some colour an odd number of times. We conjecture that such a colouring can be done using three colours. We prove that this conjecture is true for 2-connected cubic plane graphs. Next we consider other...
Combinatorial aspects of an exact sequence that is related to a graphs.
Combinatorics of orientation reversing polygons.
Compact compatible topologies for graphs with small cycles.
Compositions of maps and hypermaps. (Compositions des cartes et hypercartes.)
Configuration spaces of weighted graphs in high dimensional Euclidean spaces.
Confluent drawings: visualizing non-planar diagrams in a planar way.
Congestion optimale du plongement de l’hypercube dans la chaîne
Congruence classes of orientable 2-cell embeddings of bouquets of circles and dipoles.
Connected domatic number in planar graphs
A dominating set in a graph is a connected dominating set of if it induces a connected subgraph of . The connected domatic number of is the maximum number of pairwise disjoint, connected dominating sets in . We establish a sharp lower bound on the number of edges in a connected graph with a given order and given connected domatic number. We also show that a planar graph has connected domatic number at most 4 and give a characterization of planar graphs having connected domatic number 3.
Connected simple graphs and a selection problem
Connection on differential modules