Basic Prolog program

I am new to start this language, there is a problem that cannot be solved. There are two buttons: button a and button b. and two lights: light p and light q. Rule: - pressing button a the light p will be on. - pressing button b will interchanges p and q. - initially, p and q are off. - goal: p and q are on. Use the Prolog language to solve this question. Only use clauses of the form like this: p(T+1) :- ... q(T+1) :- ... Using the following action names: name: press_a, meaning: press button a name: press_b, meaning: press button b the rule T+1 instantiated by 1 and T instantiated by 0, and the additional fact press_a(0). the program should mention these six atoms:p(1),p(1),p(0),p(0),press_a(0),press_b(0). The part of my code, but I am not sure if it is correct: p(T+1) :- press_a(T),not p(T). p(T+1) :- q(T), not p(T), press_b(T). q(T+1) :- not q(T), p(T), press_b(T).