Satgraphs and independent domination: part 1

  • Authors:
  • Igor Edm. Zverovich

  • Affiliations:
  • RUTCOR--Rutgers Center for Operations Research, Rutgers, The State University of New Jersey, Piscataway, NJ

  • Venue:
  • Theoretical Computer Science
  • Year:
  • 2006

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Abstract

A graph G is called a satgraph if there exists a partition A ∪ B = V(G) such that • A induces a clique [possibly, A = 0], • B induces a matching [i.e., G(B) is a 1-regular subgraph, possibly, B = 0], and • there are no triangles (a, b, b'), where a ∈ A and b, b' ∈ B.We also introduce the hereditary closure of IAJ, denoted by HIAJ [hereditary satgraphs]. The class HIAJ contains split graphs. In turn, HIAJ is contained in the class of all (1, 2)-split graphs [A. Gyárfás, Generalized split graphs and Ramsey numbers, J. Combin. Theory Ser. A 81 (2) (1998) 255-261], the latter being still not characterized. We characterize satgraphs in terms of forbidden induced subgraphs.There exist close connections between satgraphs and the satisfiability problem [SAT]. In fact, SAT is linear-time equivalent to finding the independent domination number in the corresponding satgraph. It follows that the independent domination problem is NP-complete for the hereditary satgraphs. In particular, it is NP-complete for perfect graphs.