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On Ramsey properties of classes with forbidden trees (1111.0674v5)
Published 2 Nov 2011 in math.CO and cs.DM
Abstract: Let F be a set of relational trees and let Forbh(F) be the class of all structures that admit no homomorphism from any tree in F; all this happens over a fixed finite relational signature $\sigma$. There is a natural way to expand Forbh(F) by unary relations to an amalgamation class. This expanded class, enhanced with a linear ordering, has the Ramsey property.