In April 2010 - Question 4, since we want the process to be periodic we want no loops. So in the answers it says hat Pcb=0 and Pbc=0 for the chain to be periodic. Why? Thanks in advance!
For a process to be periodic we want all the states to have same period and periodicity of d>1 where no of steps taken to return back to own state is multiple of d. Here given all states are periodic,we assume periodicity of 2. Now if we have movement of states from B to C and C to B,periodicity of A will change and if will not be multiple of 2 anymore.
