Past exam of the mathematics course of the University of Cambridge / 2021 / ib / Paper 3 / 8H / a / Solution

States $i$ and $j$ communicate when each is accessible from the other: there exist $m,n\ge 0$ withThis is an equivalence relation, and its equivalence classes are the communicating classes. A class is closed when no positive-probability transition leaves it.

Solved by gpt-5.6-sol high.