Complexity Results for Generating Subgraphs

Vadim E. Levit, David Tankus

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


A graph G is well-covered if all its maximal independent sets are of the same cardinality. Assume that a weight function w is defined on its vertices. Then G is w-well-covered if all maximal independent sets are of the same weight. For every graph G, the set of weight functions w such that G is w-well-covered is a vector space, denoted WCW(G). Let B be a complete bipartite induced subgraph of G on vertex sets of bipartition BX and BY. Then B is generating if there exists an independent set S such that S∪ BX and S∪ BY are both maximal independent sets of G. In the restricted case that a generating subgraph B is isomorphic to K1 , 1, the unique edge in B is called a relating edge. Deciding whether an input graph G is well-covered is co-NP-complete. Therefore finding WCW(G) is co-NP-hard. Deciding whether an edge is relating is NP-complete. Therefore, deciding whether a subgraph is generating is NP-complete as well. In this article we discuss the connections among these problems, provide proofs for NP-completeness for several restricted cases, and present polynomial characterizations for some other cases.

Original languageEnglish
Pages (from-to)2384-2399
Number of pages16
Issue number8
StatePublished - 1 Aug 2018


  • Generating subgraph
  • Maximal independent set
  • Relating edge
  • Vector space
  • Weighted well-covered graph


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