منابع مشابه
Oriented Interval Greedoids
We propose a definition of an oriented interval greedoid that simultaneously generalizes the notion of an oriented matroid and the construction on antimatroids introduced by L. J. Billera, S. K. Hsiao, and J. S. Provan in Enumeration in convex geometries and associated polytopal subdivisions of spheres [Discrete Comput. Geom. 39 (2008), no. 1-3, 123–137]. As for of oriented matroids, associated...
متن کاملWell-covered Graphs and Greedoids
G is a well-covered graph provided all its maximal stable sets are of the same size (Plummer, 1970). S is a local maximum stable set of G, and we denote by S ∈ Ψ(G), if S is a maximum stable set of the subgraph induced by S ∪ N(S), where N(S) is the neighborhood of S. In 2002 we have proved that Ψ(G) is a greedoid for every forest G. The bipartite graphs and the trianglefree graphs, whose famil...
متن کاملGraph Operations that are Good for Greedoids
S is a local maximum stable set of G, and we write S 2 (G), if S is a maximum stable set of the subgraph induced by S [N(S), where N(S) is the neighborhood of S. Nemhauser and Trotter Jr. [5] proved that any S 2 (G) is a subset of a maximum stable set of G. In [1] we have proved that (G) is a greedoid for every forest G. The cases of bipartite graphs and triangle-free graphs were analyzed in [2...
متن کاملGreedoids on Vertex Sets of Unicycle Graphs
A maximum stable set in a graph G is a stable set of maximum size. S is a local maximum stable set of G, and we write S ∈ Ψ(G), if S is a maximum stable set of the subgraph induced by S ∪ N(S), where N(S) is the neighborhood of S. G is a unicycle graph if it owns only one cycle. It is known that the family Ψ(T ) of a forest T forms a greedoid on its vertex set. In this paper we completely chara...
متن کاملCharacterizations of Transversal and Fundamental Transversal Matroids
A result of Mason, as refined by Ingleton, characterizes transversal matroids as the matroids that satisfy a set of inequalities that relate the ranks of intersections and unions of nonempty sets of cyclic flats. We prove counterparts, for fundamental transversal matroids, of this and other characterizations of transversal matroids. In particular, we show that fundamental transversal matroids a...
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ژورنال
عنوان ژورنال: European Journal of Combinatorics
سال: 1997
ISSN: 0195-6698
DOI: 10.1006/eujc.1992.0072