Graph operations that are good for greedoids

  • Authors:
  • Vadim E. Levit;Eugen Mandrescu

  • Affiliations:
  • Department of Computer Science and Mathematics, Ariel University Center of Samaria, Israel;Department of Computer Science, Holon Institute of Technology, Israel

  • Venue:
  • Discrete Applied Mathematics
  • Year:
  • 2010

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Abstract

S is a local maximum stable set of a graph G, and we write S@?@J(G), if the set S is a maximum stable set of the subgraph induced by S@?N(S), where N(S) is the neighborhood of S. In Levit and Mandrescu (2002) [5] we have proved that @J(G) is a greedoid for every forest G. The cases of bipartite graphs and triangle-free graphs were analyzed in Levit and Mandrescu (2003) [6] and Levit and Mandrescu (2007) [7] respectively. In this paper we give necessary and sufficient conditions for @J(G) to form a greedoid, where G is: (a)the disjoint union of a family of graphs; (b)the Zykov sum of a family of graphs; (c)the corona X@?{H"1,H"2,...,H"n} obtained by joining each vertex x of a graph X to all the vertices of a graph H"x.