Self-Dual Ramsey Degrees for Trees

Abstract

We consider a Ramsey statement for pairs of maps between trees, where one is an embedding as defined by Deuber and the other is a rigid surjection as defined by Solecki. We show that there is no Ramsey Theorem for pairs of maps where the coloring depends on both coordinates. On the other hand, we give a characterization of the Ramsey degrees for such pairs. Furthermore, we show that our theorem on Ramsey Degrees for pairs of maps between trees implies the Ramsey Theorem for pairs of maps between linear orders as proved by Solecki.