AbstractGraphs, regarded as grammar forms as well as coloring specifications, induce graph-families, so-called color-families. It can be shown that for each color-family a unique (vertex) minimal graph exists. In this paper an operation on such minimal graphs is presented. As a main result it is shown that in a minimal graph G with m vertices, none of them adjacent to all other vertices, cliques have less than 12m vertices and this bound cannot be improved
AbstractSeymour (Quart. J. Math. Oxford 25 (1974), 303–312) proved that a minimal non 2-colorable hy...
Let F be a graph and let , denote nonempty families of graphs. We write F → (,) if in any 2-coloring...
summary:In this paper, we show that the maximal number of minimal colourings of a graph with $n$ ver...
AbstractGraphs, regarded as grammar forms as well as coloring specifications, induce graph-families,...
summary:In this paper, we show that the maximal number of minimal colourings of a graph with $n$ ver...
summary:In this paper, we show that the maximal number of minimal colourings of a graph with $n$ ver...
summary:In this paper we characterize $k$-chromatic graphs without isolated vertices and connected $...
summary:In this paper we characterize $k$-chromatic graphs without isolated vertices and connected $...
AbstractLet P be a property of graphs. A graph G is vertex (P,k)-colourable if the vertex set V(G) o...
AbstractWe determine the minimum number of vertices an edge-colored graph must have, if its group of...
AbstractA mechanism for constructing families of “similar” graphs is introduced. This mechanism is e...
AbstractA defining set (of vertex coloring) of a graph G is a set of vertices S with an assignment o...
Let F be a graph and let G, H denote nonempty families of graphs. We write F → (G,H) if in any 2-col...
AbstractFollowing the arrow notation, for a graph G and natural numbers a1,a2,…,ar we write G→(a1,a2...
AbstractWe disprove a conjecture of [Cook and Evans (1979)] by providing a number (the Stirling numb...
AbstractSeymour (Quart. J. Math. Oxford 25 (1974), 303–312) proved that a minimal non 2-colorable hy...
Let F be a graph and let , denote nonempty families of graphs. We write F → (,) if in any 2-coloring...
summary:In this paper, we show that the maximal number of minimal colourings of a graph with $n$ ver...
AbstractGraphs, regarded as grammar forms as well as coloring specifications, induce graph-families,...
summary:In this paper, we show that the maximal number of minimal colourings of a graph with $n$ ver...
summary:In this paper, we show that the maximal number of minimal colourings of a graph with $n$ ver...
summary:In this paper we characterize $k$-chromatic graphs without isolated vertices and connected $...
summary:In this paper we characterize $k$-chromatic graphs without isolated vertices and connected $...
AbstractLet P be a property of graphs. A graph G is vertex (P,k)-colourable if the vertex set V(G) o...
AbstractWe determine the minimum number of vertices an edge-colored graph must have, if its group of...
AbstractA mechanism for constructing families of “similar” graphs is introduced. This mechanism is e...
AbstractA defining set (of vertex coloring) of a graph G is a set of vertices S with an assignment o...
Let F be a graph and let G, H denote nonempty families of graphs. We write F → (G,H) if in any 2-col...
AbstractFollowing the arrow notation, for a graph G and natural numbers a1,a2,…,ar we write G→(a1,a2...
AbstractWe disprove a conjecture of [Cook and Evans (1979)] by providing a number (the Stirling numb...
AbstractSeymour (Quart. J. Math. Oxford 25 (1974), 303–312) proved that a minimal non 2-colorable hy...
Let F be a graph and let , denote nonempty families of graphs. We write F → (,) if in any 2-coloring...
summary:In this paper, we show that the maximal number of minimal colourings of a graph with $n$ ver...