一个使用prolog的专家系统，有一个永远无法满足的预测

以上是我的prolog代码（从互联网下载），这些行：

xpositive(symbol,symbol).
xnegative(symbol,symbol).
run:-animal_is(X), !,write("\nYour animal may be a"),write(X),nl, nl, clear_facts.
run:-write("\nUnable to determine what"),clear_facts.
positive(X,Y):-write("\npositive(X,Y)0\n"),xpositive(X, Y), ! .
positive(X,Y):-write("\npositive(X,Y)1\n"),not(xnegative(X, Y)),ask(X, Y).
negative(X,Y):-write("\nnegative(X,Y)0\n"),xnegative(X, Y), !.
negative(X,Y):-write("\nnegative(X,Y)1\n"),not(xpositive(X, Y)),ask(X, Y).
ask(X,Y):-write("\nask \n"),write(X),write(" it "),write(Y),readln(R),write("\n0000000000000\n"),new_rules(X,Y,R).
new_rules(X, Y, y):-write("\n01111111111110\n"),assert(xpositive(X, Y)).
new_rules(X, Y, n):-write("\n02222222222220\n"),assert(xnegative(X, Y)), fail.
clear_facts:-retract(xpositive(_,_)) , fail.
clear_facts:-retract(xnegative(_,_)), fail.
clear_facts:-write("\nExit\n").
it_is(mammal):-write("\nit_is(mammal)0\n"),positive( has, hair).
it_is(mammal):-write("\nit_is(mammal)1\n"),positive( does, give_milk).
it_is(bird):-positive( has, feathers).
it_is(bird):-positive( does, fly),positive(does, lay_eggs).
it_is(carnivore):-positive(does, eat_meat).
it_is(carnivore):-positive(has, pointed_teeth),positive(has, claws),positive(has, forward_eyes).
it_is(ungulate):-it_is(mammal),positive( has, hooves).
it_is(ungulate):-it_is( mammal),positive( does, chew_cud).
animal_is(cheetah):-it_is( mammal) , it_is( carnivore),positive( has, tawny_color),positive(has, black_spots).
animal_is( tiger) :-it_is( mammal),it_is( carnivore) , positive( has, tawny_color) , positive( has,black_stripes).
animal_is(giraffe):- it_is(ungulate) ,positive(has, long_neck) , positive(has, long_legs),positive(has, dark-_spots) .

---

是指向用户提问，然后在系统中陈述新的事实。但是预测“新规则”无法满足，因为“01111110”或“0222220”无法打印到屏幕上，因此系统无法使用答案！！我只是不知道为什么！！非常感谢你的建议

我不完全确定您的程序应该如何处理所有这些0、1和2，因此为了回答您的建议请求，这里有一个SWI Prolog中的程序工作版本（它也有助于指定您使用的Prolog版本）

-RdR（注：如果你喜欢答案，别忘了投票）

---

我不完全确定您的程序应该如何处理所有这些0、1和2，因此，为了回答您的建议请求，这里有一个SWI Prolog中的程序工作版本（它也有助于指定您使用的Prolog版本）

-RdR（注：如果你喜欢答案，别忘了投票）

---

这是一个很好的答案！非常感谢！这是一个很好的回答！非常感谢你！

ask(X,Y):-write("\nask \n"),write(X),write(" it "),write(Y),readln(R),write("\n0000000000000\n"),new_rules(X,Y,R).

new_rules(X, Y, y):-write("\n01111111111110\n"),assert(xpositive(X, Y)).

new_rules(X, Y, n):-write("\n02222222222220\n"),assert(xnegative(X, Y)), fail.

:- dynamic xpositive/2, xnegative/2.

run:- write("\nAnalyse your animal...\n"), 
      clear_facts,
      animal_is(X),
      write("\nYour animal may be a "),
      writeln(X),nl.
run:- write("\nUnable to determine more\n").

clear_facts:-retractall(xpositive(_,_)), retractall(xnegative(_,_)).


positive(X,Y):-xpositive(X, Y), ! .
positive(X,Y):-not(xnegative(X, Y)),ask(X, Y).
negative(X,Y):-xnegative(X, Y), !.
negative(X,Y):-not(xpositive(X, Y)),ask(X, Y).

ask(X,Y):-
  format("~n~w it ~w (y/n)? ",[X,Y]),
  get_single_char(Ch),
  char_code(C,Ch),
  new_rule(X,Y,C).

new_rule(X, Y, 'y'):-assert(xpositive(X, Y)),!.
new_rule(X, Y, 'n'):-assert(xnegative(X, Y)),!,fail.


it_is(mammal):-positive( has, hair).
it_is(mammal):-positive( does, give_milk).
it_is(bird):-positive( has, feathers).
it_is(bird):-positive( does, fly),positive(does, lay_eggs).
it_is(carnivore):-positive(does, eat_meat).
it_is(carnivore):-positive(has, pointed_teeth),
    positive(has, claws),positive(has, forward_eyes).
it_is(ungulate):-it_is(mammal),positive( has, hooves).
it_is(ungulate):-it_is( mammal),positive( does, chew_cud).

animal_is(cheetah):-it_is( mammal) , it_is( carnivore),
    positive( has, tawny_color),positive(has, black_spots).
animal_is( tiger) :-it_is( mammal),it_is( carnivore) , 
    positive( has, tawny_color) , positive( has,black_stripes).
animal_is(giraffe):- it_is(ungulate) ,positive(has, long_neck),
    positive(has, long_legs),positive(has, dark_spots).