### prolog sets problem, **stack** overflow

##### - by garm0nboz1a

Hi. I'm gonna show some code and ask, what could be optimized and where am I sucked?
sublist([], []).
sublist([H | Tail1], [H | Tail2]) :-
sublist(Tail1, Tail2).
sublist(H, [_ | Tail]) :-
sublist(H, Tail).
less(X, X, _).
less(X, Z, RelationList) :-
member([X,Z], RelationList).
less(X, Z, RelationList) :-
member([X,Y], RelationList),
less(Y, Z, RelationList),
\+less(Z, X, RelationList).
lessList(X, LessList, RelationList) :-
findall(Y, less(X, Y, RelationList), List),
list_to_set(List, L),
sort(L, LessList), !.
list_mltpl(List1, List2, List) :-
findall(X, (
member(X, List1),
member(X, List2)),
List).
chain([_], _).
chain([H,T | Tail], RelationList) :-
less(H, T, RelationList),
chain([T|Tail], RelationList),
!.
have_inf(X1, X2, RelationList) :-
lessList(X1, X1_cone, RelationList),
lessList(X2, X2_cone, RelationList),
list_mltpl(X1_cone, X2_cone, Cone),
chain(Cone, RelationList),
!.
relations(List, E) :-
findall([X1,X2],
(member(X1, E),
member(X2, E),
X1 =\= X2),
Relations),
sublist(List, Relations).
semilattice(List, E) :-
forall(
(member(X1, E),
member(X2, E),
X1 < X2),
have_inf(X1, X2, List)
).
main(E) :-
relations(X, E),
semilattice(X, E).
I'm trying to model all possible graph sets of N elements.
Predicate relations(List, E) connects list of possible graphs(List) and input set E.
Then I'm describing semilattice predicate to check relations' List for some properties.
So, what I have.
1) semilattice/2 is working fast and clear
?- semilattice([[1,3],[2,4],[3,5],[4,5]],[1,2,3,4,5]).
true.
?- semilattice([[1,3],[1,4],[2,3],[2,4],[3,5],[4,5]],[1,2,3,4,5]).
false.
2) relations/2 is working not well
?- findall(X, relations(X,[1,2,3,4]), List), length(List, Len), writeln(Len),fail.
4096
false.
?- findall(X, relations(X,[1,2,3,4,5]), List), length(List, Len), writeln(Len),fail.
ERROR: Out of global

**stack**^ Exception: (11) setup_call_catcher_cleanup('$bags':'$new_findall_bag'(17852886), '$bags':fa_loop(_G263, user:relations(_G263, [1, 2, 3, 4|...]), 17852886, _G268, []), _G835, '$bags':'$destroy_findall_bag'(17852886)) ? abort % Execution Aborted 3) Mix of them to finding all possible semilattice does not work at all. ?- main([1,2]). ERROR: Out of local**stack**^ Exception: (15) setup_call_catcher_cleanup('$bags':'$new_findall_bag'(17852886), '$bags':fa_loop(_G41, user:less(1, _G41, [[1, 2], [2, 1]]), 17852886, _G52, []), _G4767764, '$bags':'$destroy_findall_bag'(17852886)) ?