%0 Journal Article %T Syndetic Sets and Amenability %A Vern I. Paulsen %J Mathematics %D 2010 %I arXiv %X We prove that if an infinite, discrete semigroup has the property that every right syndetic set is left syndetic, then the semigroup has a left invariant mean. We prove that the weak*-closed convex hull of the two-sided translates of every bounded function on an infinite discrete semigroup contains a constant function. Our proofs use the algebraic properties of the Stone-Cech compactification. %U http://arxiv.org/abs/1002.3157v2