By a theory we mean a subset of propositions that is closed under consequences and conjunctions. When the set of all propositions is a Boolean algebra, theories are filters in this algebra. When there are several theorists, they can also have theories about what theories the other theorists...

We study the existence of undominated elements of acyclic relations. A sufficient condition for the existence is given without any topological assumptions when the dominance relation is finite valued. The condition says that there is a point such that all dominance sequences starting from this...