>>807

fruit.pl
fruit_val(ringo,1).
fruit_val(banana,2).
fruit_val(ichigo,3).
fruit_val(mikan,4).
fruit_val(kiwi,5).

goukei(A,B):-
fruit_val(A,AVal),
fruit_val(B,BVal),
CVal is AVal+BVal,
fruit_val(C,CVal),
write(C).


実行結果：
[1] 20 ?- goukei(ringo,ringo).
banana
true.

[1] 21 ?- goukei(ringo,banana).
ichigo
true.