Relaxed graceful labellings of trees.
Van Bussel, Frank (2002)
The Electronic Journal of Combinatorics [electronic only]
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Van Bussel, Frank (2002)
The Electronic Journal of Combinatorics [electronic only]
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Markov, Minko (2007)
Serdica Journal of Computing
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This paper is part of a work in progress whose goal is to construct a fast, practical algorithm for the vertex separation (VS) of cactus graphs. We prove a theorem for cacti", a necessary and sufficient condition for the VS of a cactus graph being k. Further, we investigate the ensuing ramifications that prevent the construction of an algorithm based on that theorem only.
Markov, Minko (2008)
Serdica Journal of Computing
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We investigate the NP-complete problem Vertex Separation (VS) on Maximal Outerplanar Graphs (mops). We formulate and prove a “main theorem for mops”, a necessary and sufficient condition for the vertex separation of a mop being k. The main theorem reduces the vertex separation of mops to a special kind of stretchability, one that we call affixability, of submops.
Bohdan Zelinka (1990)
Časopis pro pěstování matematiky
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Piotr Borowiecki, Kristína Budajová, Stanislav Jendrol', Stanislav Krajci (2011)
Discussiones Mathematicae Graph Theory
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A parity path in a vertex colouring of a graph is a path along which each colour is used an even number of times. Let χₚ(G) be the least number of colours in a proper vertex colouring of G having no parity path. It is proved that for any graph G we have the following tight bounds χ(G) ≤ χₚ(G) ≤ |V(G)|-α(G)+1, where χ(G) and α(G) are the chromatic number and the independence number of G, respectively. The bounds are improved for trees. Namely, if T is a tree with diameter diam(T) and...
Bohdan Zelinka (1985)
Časopis pro pěstování matematiky
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Ralph J. Faudree, Ronald J. Gould, Michael S. Jacobson (2013)
Discussiones Mathematicae Graph Theory
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For a fixed graph F, a graph G is F-saturated if there is no copy of F in G, but for any edge e ∉ G, there is a copy of F in G + e. The minimum number of edges in an F-saturated graph of order n will be denoted by sat(n, F). A graph G is weakly F-saturated if there is an ordering of the missing edges of G so that if they are added one at a time, each edge added creates a new copy of F. The minimum size of a weakly F-saturated graph G of order n will be denoted by wsat(n, F). The graphs...