A graph G is called normal if there exist two coverings, C and
S of its vertex set such that every member of C induces a
clique in G, every member of S induces an independent set in G
and C∩S=∅ for every C∈C and S∈S. It has been conjectured by De Simone and K\"orner in 1999 that a
graph G is normal if G does not contain C5, C7 and C7
as an induced subgraph. We disprove this conjecture