Co-Accessibility 

Description : This program obtains the co-accessible part of the FSM h. 
		   A co-accessible machine is an accessible machine such
                that any state can reach a marked state.
               
Input         : H.fsm - Input FSM                                        

Output        : H_co_acc.fsm - Co-accessible FSM

Example

H

Output machine

H FSM

Output FSM

States C3 is not present in the output machine because there exists no path between it and a marked state (C), whereas C2 remains because a path does exists (namely {c, b}).