Branching-Time as a relative closeness relation among histories

In the traditional approaches to branching-time, histories are dened as linearly ordered and maximal sets of moments. The `geometrical' approach considers both moments and histories as primitive entities with no set-theoretical and ontological dependency of the latter on the former. In the a topological approach the original perspective is inverted: only histories are primitive entities and moments are dened as sets of histories. Moreover, these particular sets of histories can be dened also by means of a relative closeness relation among histories.