Relative complements and a `switch'-classification of simple graphs

In the paper we introduce and study a classification of finite (simple, undirected, loopless) graphs with respect to a switch-equivalence (`local-complement' equivalence of \cite{pascvebl}, an analogue of the complement-equivalence of \cite{conell}). In the paper we propose a simple inductive method to compute the number of switch-types of graphs on $n$ vertices and we show that there are exactly 16 such types of graphs on 6 vertices.