% Demostrate the use of 'fact'
:- eval(test020()).

symmetric(a).

symmetric(X) :-
	b=X.

test020() :-
	println(["==========test020=========="]),
	assert(symmetric(c)),
	% Only 'symmetric' facts will be used
	fact(symmetric(X)),
	println(["Rule A: symmetric= ",X]).
test020() :-
	% Both 'symmetric' facts and rule will be used
	symmetric(X),
	println(["Rule B: symmetric= ",X]).
