:: deftheorem Def13 defines perfect CHORD:def 13 :
for G being _finite _Graph
for S being VertexScheme of G holds
( S is perfect iff for n being non zero Nat st n <= len S holds
for Gf being inducedSubgraph of G,(S .followSet n)
for v being Vertex of Gf st v = S . n holds
v is simplicial );