Graph parameters and semigroup functions

Abstract. We prove a general theorem on semigroup functions that implies characterizations of graph partition functions in terms of the positive semidefiniteness (`reflection positivity') and rank of certain derived matrices. The theorem applies to undirected and directed graphs and to hypergraphs.

• Type: Journal
• Year: 2008
• Where: EJC
• Authors: László Lovász, Alexander Schrijver
• Keywords: Certain Derived Matrices, EJC 2007, EJC 2008, Graph Partition Functions, Information Technology, Semigroup Functions