Handling all possible results in prolog -


i have clause is_adjacent([x1,y1], [x2,y2]) true, when [x2,y2] neighbor of [x1,y1]. possible results (four) if ask is_adjacent([2,2], [x,y]), in case:

is_adjacent([2,2],[x,y]). x = 2, y = 3 ; x = 3, y = 2 ; x = 2, y = 1 ; x = 1, y = 2.

i want use behavior in clause:

anotherclause :-     is_adjacent([2,2],[x,y]),     [to continued...].

now, how can work automatically every possible result? example if want check if every single result member of specific list.

thanks answers!

there forall/2, seems fit requirements:

% fails because not results in list anotherclause :-     forall(is_adjacent([2, 2], [x, y]),            memberchk([x, y], [[2, 3], [3, 2]])).  % succeed, results in list anotherclause :-     forall(is_adjacent([2, 2], [x, y]),            memberchk([x, y], [[2, 3], [3, 2], [1, 2], [2, 1]])).

for test purpose, coded is_adjacent way:

is_adjacent([a, b], [x, y]) :-     member(u / v, [1 / 0, 0 / 1, -1 / 0, 0 / -1]),     x + u, y b + v.

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