%%%%%%%%%%%%%%%%%%  element/2  %%%%%%%%%%%%%%%%%%%%%%%%
term(list([]),[]).
term(list([X|Y]),[item(X),list(Y)]).

literal(element(X,Y),[item(X),list(Y)]).

bg([]).

query1(Clauses):-
	induce_spec([+element(a,[a,b]),
	             -element(x,[a,b]),
	             +element(b,[b]),
  	             +element(b,[a,b])
	            ],Clauses).