Inverse Factorial Function (Prolog)

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Published on 2013-11-12T21:50:46Z Indexed on 2013/11/12 21:53 UTC
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I have to write a Prolog program to computer the inverse of factorial function without using division. I was also given the note: "the inverse of a function is not necessarily a function". I have this is a normal factorial predicate..

fact(0,1). fact(N,F) :- N>0, N1 is N-1, fact(N1,F1), F is N * F1.

I've read on some other posts that you should be able to just switch around the arguments, but that doesn't seem to be the case with this version. Could anyone help me out with figuring out why?

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