In set theory and in the context of a large cardinal property, a subset, S, of D is homogeneous for a function if f is constant on size- subsets of S.[1]p. 72 More precisely, given a set D, let be the set of all size- subsets of (see Powerset § Subsets of limited cardinality) and let be a function defined in this set. Then is homogeneous for if .[1]p. 72[2]p. 1
Ramsey's theorem can be stated as for all functions , there is an infinite set which is homogeneous for .[2]p. 1