notStandardExampleTheory

The database used in Prolog standard while writing examples for Not

shave(barber, X) :- \+ shave(X, X).

test_Prolog_unifiable(X, Y) :- \+ \+ X = Y.

p1 :- \+ q1.
q1 :- fail.
q1 :- true.
p2 :- \+ q2.
q2 :- !, fail.
q2 :- true.