An infinite family of graphs F is called feasible if for any pair of
integers (n,m), nβ₯1, 0β€mβ€(2nβ), there is a member
GβF such that G has n vertices and m edges. We prove that
given a graph G, the family F(G) of all induced G-free graphs is
feasible if and only if G is not Kkβ, Kkβ\K2β,
Kkββ, Kkβ\K2ββ, for kβ₯2