I’m assuming you are using swi interactively and trying to enter the fact gives you an error like so:
1 ?- like(x, y).
ERROR: toplevel: Undefined procedure: like/2 (DWIM could not correct goal)
Since the fact does not exist in the database.
If this is the case, try asserting the fact first:
2 ?- assert(like(x,y)).
true.
Then you can try:
3 ?- like(x, y).
true.
This time the query succeeds because the fact exists in the database.
A better approach might be to write your clauses into a file & then consult them.
Swi prolog has an emacs-like editor that you can bring up by typing
emacs.
at the prompt. Or use your own editor & then consult the file. Swi prolog
comes with a lot of graphical tools that might be of help; look at the manual
for more details.