The graph sandwich problem for property Phi is defined as follows: Giv
en two graphs G(1) = (V, E-1) and G(2) = (V, E-2) such that E-1 subset
of or equal to E-2, is there a graph G = (V, E) such that E-1 subset
of or equal to E subset of or equal to E-2 which satisfies property Ph
i? We present a polynomial-time algorithm for solving the graph sandwi
ch problem, when property Phi is ''to contain a homogeneous set''. The
algorithm presented also provides the graph G and a homogeneous set i
n G in case it exists. (C) 1998 Elsevier Science B.V. All rights reser
ved.