Some basic problems:-

Problem 1;

1> p 
2> (p => q)
3> (q => r)
4> ok

?- r

Problem 2;

1> ok

?- (~ (p & (~ p)))

1> (p <=> q)
2> ok

?- (q <=> p)

Problem 3;

1> ((all x) ((f x) => (g x)))
2> (f a)
3> ok

?- (g a)

Problem 4;

1> ((some x) (all y) (father x y))
2> ok

?- ((all y) (some x) (father x y))
