I'm trying to learn the basics of Prolog and keep running into a existence_error with the following code. comes_after(m1, m2). comes_after(m2, m3). comes_after(m3, m4). comes_after(m4, m5). comes_...

Are there any up-to-date Prolog implementation benchmarks (with results)? I found this on the mercury web site. Surprisingly, it shows a 20-fold gap between swi-prolog and Aquarius. I suspect that ...

I wrote a quick predicate in Prolog trying out CLP(FD) and its ability to solve systems of equations. problem(A, B) :- A-B #= 320, A #= 21*B. When I call it in SWI, I get: ?- problem(A,B). 32...

Is there a way to 'trap' (e.g. 'catch') an operating system signal within GNU Prolog? (I'm using Ubuntu/Linux, latest gprolog). I think a long time ago I used this approach in WAMCC, before that m...

While using gprolog I often have exceptions without any kind of line numbers or context like this one: uncaught exception: error(instantiation_error,(is)/2) Without any kind of context. I know I...

I am new to Prolog, but I am stuck at this supposedly simple command. I have loaded a knowledge base with no errors, and whenever I try do assert (and even help) I get the following message: uncau...

I'm new to prolog and want to save all queries in a file instead of typing them by hand. I have these facts in facts.pl: likes(wallace, cheese). likes(grommit, cheese). likes(wendolene, sheep). ...

I have a Prolog database file (test_inserts.p) that I used to insert all my data. I also have a Prolog query file (test_queries.pl) that has all of the Prolog queries I wrote up to receive specifi...

I'd like to use predicates like: range(X,0,5) range(X,4,200) range(X,-1000000,1000000) dom_range(X,-1000000,1000000) with meaning : range(X,0,5) :- member(X,[0,1,2,3,4,5]). range(X,4,200) :- me...

There is a lack of some predicates in one Prolog implementations, that are available in others. We can implement lacking predicates, let's call this "Prolog Compatibility Layer". Do you know "Pro...

I'm trying to keep my Prolog code modular, and I was wondering if anyone had any advice as to how to do this. The way I was doing this with simple consults, but that is getting cumbersome as the nu...

I'm reading "Seven languages in seven weeks" atm, and I'm stumped over some Prolog query that I don't understand the 'no' response to. The friends.pl file looks like this: likes(wallace, cheese)....