Canonical forms for frequent graph mining

A core problem of approaches to frequent graph mining, which are based on growing subgraphs into a set of graphs, is how to avoid redundant search. A powerful technique for this is a canonical description of a graph, which uniquely identifies it, and a corresponding test. I introduce a family of canonical forms based on systematic ways to construct spanning trees. I show that the canonical form used in gSpan (Yan and Han (2002)) is a member of this family, and that MoSS/MoFa (Borgelt and Berthold (2002), Borgelt et al. (2005)) is implicitly based on a different member, which I make explicit and exploit in the same way.