My code is:

parent(pamela, bob). parent(tom, bob). parent(tom, liz). parent(bob, ann). parent(bob, patricia). parent(patricia, jim). ancestor(X, Y) :- parent(X, Y); ancestor(X, Z), parent(Z, Y). query2 :- ancestor(bob, patricia).

On request:

 query2.

Gives an error message:

 Actions: ; (n, r, space, TAB): redo t: trace & redo b: break c (a, RET): exit w: write p print h (?): help ERROR: char_code/2: Cannot represent due to `character_code' true Action?

Launched in the online translator ( link ).

What did I do wrong?

  • one
    Yes, everything seems to be correct, even the correct answer was given by the system. I asked for the parent(X, Y) predicate, it gives the correct answers, but this error remains, I launched it on swi, everything works. There are no such errors. It feels like this is something with the interpreter happens at the moment when he needs to request additional actions from the user - Cost
  • Clearly, I will then switch to swi, online editors are only suitable as a temporary measure ... - zcorvid

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