accessibility relation

An accessibility relation is a concept used in logic and computer science to describe how different states or points in a system can be reached from one another. Imagine a map where each city represents a state, and roads connect them. The accessibility relation indicates which cities you can travel to directly from a given city. It helps analyze what possibilities exist within a system, such as whether a process can reach a certain condition or state from its starting point. This idea is fundamental in understanding how systems evolve and whether certain outcomes are possible.