Query and answer | |
?- integer(I). false. |
No integer exists. |
?- integer(3). true. |
Yet, 3 is an integer. |
?- X \= Y. false. |
There are no terms for which X \= Y holds. |
?- a \= b. true. |
In contrast to what the system just said, X \= Y does hold for example for X = a and Y = b. |
?- X =:= Y. ERROR: =:=/2: ... |
Insufficient instantiation. |
?- 3 =:= X, X =:= Y. ERROR: =:=/2: ... |
Insufficient instantiation. |
Query and answer | |
?- I in inf..sup. I in inf..sup. |
True iff I is an integer. |
?- 3 in inf..sup. true. |
In particular, 3 is an integer. |
?- dif(X, Y). dif(X, Y). |
The query holds iff X and Y are different terms. |
?- dif(a, b). true. |
In particular, dif(X, Y) holds for example for X = a and Y = b. |
?- X #= Y. X = Y, Y in inf..sup. |
The query holds iff X and Y are the same integer. |
?- 3 #= X, X #= Y. X = Y, Y = 3. |
In particular, it holds if X and Y are equal to 3. |