For any finite abelian group G and any subset S ⊆ G, we determine the connectivity of the addition Cayley graph induced by S on G. Moreover, we show that if this graph is not complete, then it possesses a minimum vertex cut of a special, explicitly described form. 1. Background: addition Cayley graphs For a subset S of the abelian group G, we denote by Cay+G(S) the addition Cayley graph induced...