由於第一次接觸PROLOG，所以語法不熟，不知道怎麼除錯.. 可以請大大幫我看一下嗎?謝謝~ % Candidate Elimination Algorithm run_candidate_elim :- candidate_elim([[_,_,_]], [], [[small, medium, large], [red, blue, green], [ball, brick, cube]]). % Candidate_elim implements a top level read-process loop % It prints out the current G set % the S set % % and calls process to process the input. candidate_elim([G],[S],_) :- covers(G,S),covers(S,G), write("target concept is "), write(G),nl. candidate_elim(G, S, Types) :- write("G= "), write(G),nl, write("S= "), write(S),nl, write("Enter Instance "), read(Instance), process(Instance, G, S, Updated_G, Updated_S, Types), candidate_elim(Updated_G, Updated_S, Types). % Process takes the instance, % a set of concepts, G and % and a set of concepts, S % it implements a step of the candidate elimination algorithm. process(negative(Instance), G, S, Updated_G, Updated_S, Types) :- delete(X, S, covers(X, Instance), Updated_S), specialize_set(G,Spec_G, Instance, Types), delete(X, Spec_G, (member(Y, Spec_G), more_general(Y, X)), Pruned_G), delete(X, Pruned_G, (member(Y, Updated_S), not(covers(X, Y))), Updated_G). process(positive(Instance), G, [], Updated_G, [Instance],_):- % Initialize S delete(X, G, not(covers(X, Instance)), Updated_G). process(positive(Instance), G, S, Updated_G, Updated_S,_) :- delete(X, G, not(covers(X, Instance)), Updated_G), generalize_set(S,Gen_S, Instance), delete(X, Gen_S, (member(Y, Gen_S), more_general(X, Y)), Pruned_S), delete(X, Pruned_S, not((member(Y, Updated_G), covers(Y, X))), Updated_S). process(Input, G, P, G, P,_):- Input \= positive(_), Input \= negative(_), write("Enter either positive(Instance) or negative(Instance) "), nl % The following predicate definitions are duplicated in either % the general to specific searches or the specific to genearal searches. % specialize_set([], [], _, _). ERROR: c:/candidate1.pl:54:0: Syntax error: Operator expected specialize_set([Hypothesis|Rest],Updated_H,Instance, Types):- covers(Hypothesis, Instance), (bagof(Hypothesis, specialize(Hypothesis, Instance, Types), Updated_head); Updated_head = []), specialize_set(Rest, Updated_rest, Instance, Types), append(Updated_head, Updated_rest, Updated_H). specialize_set([Hypothesis|Rest],[Hypothesis|Updated_rest],Instance, Types):- not (covers(Hypothesis, Instance)), specialize_set(Rest,Updated_rest, Instance, Types). specialize([Prop|_], [Inst_prop|_], [Instance_values|_]):- var(Prop), member(Prop, Instance_values), Prop \= Inst_prop. specialize([_|Tail], [_|Inst_tail], [_|Types]):- specialize(Tail, Inst_tail, Types). % generalize_set([], [], _). generalize_set([Hypothesis|Rest],Updated_H,Instance):- not(covers(Hypothesis, Instance)), (bagof(X, generalize(Hypothesis, Instance, X), Updated_H); Updated_head = []), generalize_set(Rest,Updated_rest, Instance), append(Updated_head, Updated_rest, Updated_H). generalize_set([Hypothesis|Rest],[Hypothesis|Updated_rest],Instance):- covers(Hypothesis, Instance), generalize_set(Rest,Updated_rest, Instance). % generalize([],[],[]). generalize([Feature|Rest], [Inst_prop|Rest_inst], [Feature|Rest_gen]) :- not(Feature \= Inst_prop), generalize(Rest, Rest_inst, Rest_gen). generalize([Feature|Rest], [Inst_prop|Rest_inst], [_|Rest_gen]) :- Feature \= Inst_prop, generalize(Rest, Rest_inst, Rest_gen). % more_general(Feature_vector_1, Feature_vector_2) :- succeeds if % Feature_vector_1 is strictly more general than Feature_vector_2 more_general(X, Y) :- not(covers(Y, X)), covers(X, Y). % covers(Feature_list_1, Feature_list_2) :- Succeeds if Feature_list_1 % covers Feature_list_2. Note that covers, unlike unification is % not symmetric: variables in Feature_list_2 will not match constants % in Feature_list_1. covers([],[]). covers([H1|T1], [H2|T2]) :- var(H1), var(H2), covers(T1, T2). covers([H1|T1], [H2|T2]) :- var(H1), atom(H2), covers(T1, T2). covers([H1|T1], [H2|T2]) :- atom(H1), atom(H2), H1 = H2, covers(T1, T2). % delete(Element, List1, Goal, List2) :- List2 contains all bindings % of Element to a member of List1 except those that cause % Goal to succeed delete(X, L, Goal, New_L) :- (bagof(X, (member(X, L), not(Goal)), New_L);New_L = []). 麻煩大家了~謝謝!! --

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