Generate all state reached from a transition fire
[ch,tran_ch] = findchild(forward,backward,x,tran_x)
This function is used to generate all states that can be reached by fire one transition. The input is Petri net represented by forward and backward incidence matrix also list of states and its transition firing order in matrix form. This function is called by function firingorder.
Every column of x and ch represent state. Number of column in x equal with tran_x and number of column in ch equal with tran_ch. Number of row in tran_x shows how many firing needed to reach x. The same is true for tran_ch and ch.