Thanks for your reply.

For the first part, if I use just the one state like below is it correct ? :

A_exist ({s1}, !s1, (!s1 & !p & !Xs1 | !s1 & p & Xs1 | s1 & !p & Xs1), Fs1)

For the second part:

I got your point by mistake I wrote disjunction, I will correct it.