prolog

问题 I am trying to solve Einstein Riddle in Prolog. I am having a difficulty with the program I wrote, the basic method was to add all constraints and let Prolog figure out the only possible solutions. The problem is that Prolog finds 0 solutions. I have isolated the constraint that makes the program go from a given solution to no solutions, but I don't understand why. /*There are five houses*/ exists(A, list(A,_,_,_,_)). exists(A, list(_,A,_,_,_)). exists(A, list(_,_,A,_,_)). exists(A, list(_,_,

问题 How Can I turn off warnings in swi-prolog. Clauses of XXX/AA are not together in the source-file is very annoying. 回答1: Instead, you could fix the warning. The discontiguous directive is needed when the clauses of a static (compiled) predicate cannot be compiled as a single unit. This happens when the clause definitions are: Not contiguous Exceed the maximum number of clauses 回答2: You can turn off these warnings with style_check using :-style_check(-discontiguous). . For example, you can also

问题 Let's define custom operators - let it be ++ , equals :- op(900, yfx, equals). :- op(800, xfy, ++). And fact: check(A equals A). I try to make predicate, let it be check/1 , that will return true in all following situations: check( a ++ b ++ c ++ d equals c ++ d ++ b ++ a ), check( a ++ b ++ c ++ d equals d ++ a ++ c ++ b), check( a ++ b ++ c ++ d equals d ++ b ++ c ++ a ), % and all permutations... of any amount of atoms check( a ++ ( b ++ c ) equals (c ++ a) ++ b), % be resistant to any

问题 In parsing a large 3 gigabyte file with DCG, efficiency is of importance. The current version of my lexer is using mostly the or predicate ;/2 but I read that indexing can help. Indexing is a technique used to quickly select candidate clauses of a predicate for a specific goal. In most Prolog systems, indexing is done (only) on the first argument of the head. If this argument is instantiated to an atom, integer, float or compound term with functor, hashing is used to quickly select all

问题 Suppose I have the below code in my familyTree.pl file: male(tom). male(bob). female(lisa). female(emily). parent(tom, bob). parent(lisa, bob). morethanfriends(emily, bob). father(X,Y) :- male(X), parent(X,Y). mother(X,Y) :- female(X), parent(X,Y). girlfriend(X,Y) :- female(X), (morethanfriends(X,Y); morethanfriends(Y,X)). boyfriend(X,Y) :- male(X), (morethanfriends(X,Y); morethanfriends(Y,X)). Now, I want to get the answer to the questions like: What is the relationship between Tom and Bob ?

问题 I need some help writing a predicate in Prolog that, given a number as input, returns a list of lists with numbers that add up to it. Let's call the predicate addUpList/2 , it should work like this: ?- addUpList(3,P). P = [[1,2], [2,1], [1,1,1]]. % expected result I'm having so much trouble figuring this out I'm beginning to think it's impossible. Any ideas? Thanks in advance. 回答1: Try this: condense([], Rs, Rs). condense([X|Xs], Ys, Zs) :- condense(Xs, [X|Ys], Zs). condense([X, Y|Xs], Ys, Zs

问题 In many Prolog systems it is easy to add a new search path for consulting file. In Yap for example, the predicate I know it is add_to_path(NewPath). Is there a way to do the same in SWI Prolog ?. My question is specifically about adding one path to the already existing paths, I am aware of the file_search_path/2 predicate for declaring directories, and the cd/1 predicate for changing the current directory, but I would like to know if there is an alternative method, like the one I found in Yap

问题 I have this piece of code: % Family tree female(pen). male(tom). male(bob). female(liz). female(pat). female(ann). male(jim). parent(pam, bob). parent(tom, bob). parent(tom, liz). parent(bob, ann). parent(bob, pat). parent(pat, jim). I get this error: Warning: Clauses of female/1 are not together in source-file Warning: Clauses of male/1 are not together in source-file What is the purpose of this error? I mean, file does compile and run just fine and I am aware of the meaning of the error.

问题 Given word/1 , word(W) :- abs(ABs), ABs = W. abs([]). abs([AB|ABs]) :- abs(ABs), ab(AB). ab(a). ab(b). ?- word(W). W = [] ; W = [a] ; W = [b] ; W = [a,a] ; W = [b,a] ; W = [a,b] ; W = [b,b] ; W = [a,a,a] ; W = [b,a,a] ; W = [a,b,a] ; W = [b,b,a] ; W = [a,a,b] ; W = [b,a,b] ; W = [a,b,b] ; W = [b,b,b] ; W = [a,a,a,a] ... how does a more compact definition of word/1 look like, otherwise identical w.r.t. termination and the set of solutions, fairness, with the following constraints: No use of

问题 I was wondering if you know of any way to use prolog for stream processing, that is, some kind of reactive programming, or at least to let a query run on a knowledge base that is continuously updated (effectively a stream), and continuously output the output of the reasoning? Anything implemented in the popular "prologs", such as SWI-prolog? 回答1: You can use Logtalk's support for event-driven programming to define monitors that watch for knowledge base update events and react accordingly. You