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%  Copyright 2016 Metagol authors
%  Copyright 2018-2019 Paulo Moura
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:- set_logtalk_flag(hook, metagol).


:- object(undirected_edge,
	implements(metagol_example_protocol),
	extends(metagol)).

	%% tell Metagol to use the BK
	body_pred(edge/2).

	%% metarules
	metarule([P,Q], [P,A,B], [[Q,A,B]]).
	metarule([P,Q], [P,A,B], [[Q,B,A]]).

	%% background knowledge
	edge(a,b).
	edge(b,d).
	edge(c,c).

	learn(Clauses) :-
		Pos = [
			target(a,b),
			target(b,a),
			target(b,d),
			target(d,b),
			target(c,c)
		],
		Neg = [
		],
		^^learn(Pos, Neg, Prog),
		^^program_to_clauses(Prog, Clauses).

	learn :-
		learn(Clauses),
		^^pprint_clauses(Clauses).

:- end_object.
