Home/ Questions/Q 6907339
In Process

The Archive Base Latest Questions

Editorial Team
  • 0
Asked: 2026-05-27T08:25:21+00:00

when I use prolog’s built-in predicate subtract/3 : subtract(+Set, +Delete, -Result) in for example:

  • 0

when I use prolog’s built-in predicate “subtract/3” : subtract(+Set, +Delete, -Result) in for example: 

subtract([a,b,c,d,c,c,d,e], [c,a], X).  
X = [b, d, d, e].

but I want to subtract each item in +Delete from +Set ONCE. I mean, I want 

subtract([a,b,c,d,c,c,d,e], [c,a], X). to give
X = [b, d, c, c, d, e].

How can I do this?

Share

Leave an answer

You must login to add an answer.

Need An Account,

1 Answer

  1. Editorial Team

    You can build your own procedure that does that.
    For example:

    subtract_once(List, [], List).
subtract_once(List, [Item|Delete], Result):-
  (select(Item, List, NList)->
    subtract_once(NList, Delete, Result);
    (List\=[],subtract_once(List, Delete, Result))).

    In every iteration you take one item from the list of items to remove, and extract one element from the input list, and then continue using the remainder of both lists.

    • 0