I’m trying to figure out how to calculate the fastest journey between two places, given different travel modes. My factbase starts with a predicate route(Src, Dest, Distance, TravelMode) and input is via the predicate journey(Src, Dest, TravelMode) which should output the fastest travel mode to use.…

Welcome. If you double post a question, please note it in the post. :smiley: Re: StackOverflow - Prolog - Calculate fastest travel between 2 locations given different travel modes

Oh my apologies regarding that!

I’ve been able to implement the rest of the other features as suggested by other users, however I still can’t seem to output the lowest time value. I don’t think its because I didn’t call the function since when I run all(Solutions). the output is just the same as that of find_min(MinimizedSolutions…

You can do the following: Put the elements in a flat term, not a list. Instead of: findall([City1, City2, TravelModes, Time], ...) Write: findall(path(City1, City2, TravelModes, Time), ..., Solutions) Now it is even easier to sort on Time and just take the first: sort(4, @=<, Solutions, [Faste…

Hi! Thank you for this, so that means the minimize(, Sol, Sol) and onwards predicates are not needed anymore right? I was reading the swi documentation for sort and I tried to follow it: /* Collecting all solutions */ all(Solutions) :- findall(path(City1, City2, TravelModes, Time), journey(City1…

Yes, everything else is unnecessary. You get the error because there is already a built in sort/2. I don’t see why you need to wrap the call to sort/4 to be honest. But just rename your sort/2 to something else and it should work. It seems to me, from looking at your code, that you are not findin…

Ah I see, I’m quite confused sir Boris. That being if I were to not call sort/4, how would I be able to input journey(City1, City2, TravelModes) and have an output that were to state the path with the shortest time. /* Collecting all solutions */ all(Solutions) :- findall(path(City1, City2, TravelM…

Prolog - Calculate fastest travel between 2 locations given different travel modes

Help!

abaljeu December 13, 2019, 1:29pm 3

This seems familiar. I quick search finds: Recursive travel

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Prolog - Calculate fastest travel between 2 locations given different travel modes

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