Solution
= Solution
The communicating classes are $\{1,3\}$ and $\{2,4\}$. The first is open because state 3 can enter 4 and cannot return; the second is closed.
= Solution
The communicating classes are $\{1,3\}$ and $\{2,4\}$. The first is open because state 3 can enter 4 and cannot return; the second is closed.