prolog-setof

What is the Prolog operator ^ ? Looking at The Prolog Built-in Directive op gives a list of the built-in operators. I see ** is exponentiation /\ is or but what is ^ ? Each of the three current answers are of value and I learned something: Roy for the book false for the examples I accepted the answer by CapelliC because it made clear that ^/2 has multiple meanings depending on context which instantly cleared up my confusion. In Prolog, most symbols can be used 'uninterpreted', at syntactic level, in particular after a op/3 declaration, any atom can be used as operator . Then you can use, for

I have predicate P1 that returns values one after the other like this: -? P1(ARGUMENTS, RETURN). -? RETURN = 1; -? RETURN = 2; -? RETURN = 3; -? fail. I also have another predicate called P2: P2(ARGUMENTS, LIST) :- P1(ARGUMENTS, RETURN),... % SOMEHOW HERE I NEED TO INSERT ALL VALUES OF RETURN TO LIST. How do find all of the values of RETURN and assign them to LIST ? Pesto Use findall to accomplish this: P2(ARGUMENTS, LIST) :- findall(X, P1(ARGUMENTS, X), LIST). This is related to the bagof function mentioned in the question linked to by Anders Lindahl. There is a good explanation on the

I need an ordered list of Objects that satisfy Goal. setof takes care of the ordering, but fails when no Objects satisfy Goal. I want to return an empty list instead like findall does. This works, but is there a way of accomplishing this without a cut? I'm using SWI-Prolog. setof(Object, Goal, List), !; List = []. First, ..., ( setof(Object, Goal, List), ! ; List = [] ), ... does not work, as you suggest. It always succeeds for List = [] , and it only shows the first answer of setof/3 . But setof/3 may produce several answers. The general method that works in any Prolog is: ..., ( \+ Goal ->

I had a quick question re. existential qualifier using setof in prolog (i.e. ^). using SICStus it seems that (despite what a number of websites claim), S does indeed appear to be quantified in the code below (using the bog standard, mother of / child of facts, which i havent included here): child(M,F,C) :- setof(X,(mother(S,X)),C). i check the unification using: child(M,F,C) :- setof(X-S,(mother(S,X)),C). so the following code, with the existential operator seem to make no difference: child(M,F,C) :- setof(X,S^(mother(S,X)),C). Any ideas why this is? What would be a situation where you would

My code runs but the problem is it shows the same results more than once. Here's my code: disease(hiv,[sore_throat,headache,fever,rash]). disease(pregnancy,[fatigue,vomiting,light_headedness,increased_waistline]). disease(flu,[fatigue,fever,tiredness,nasal_discharge]). diagnose([], []). diagnose(Name, [H|T]) :- disease(The_Disease, Symptoms), member(H, Symptoms), write(Name), write(' has/is '), writeln(The_Disease), diagnose(Name, T). member(X,[X|_]). member(X,[_|T]):- member(X,T). Result when executed in prolog: ?- diagnose(kevin,[sore_throat,fatigue,tiredness,rash]). kevin has/is hiv kevin

Given the following facts in a database: foo(a, 3). foo(b, 2). foo(c, 4). foo(d, 3). foo(e, 2). foo(f, 6). foo(g, 3). foo(h, 2). I want to collect all first arguments that have the smallest second argument, plus the value of the second argument. First try: find_min_1(Min, As) :- setof(B-A, foo(A, B), [Min-_|_]), findall(A, foo(A, Min), As). ?- find_min_1(Min, As). Min = 2, As = [b, e, h]. Instead of setof/3 , I could use aggregate/3 : find_min_2(Min, As) :- aggregate(min(B), A^foo(A, B), Min), findall(A, foo(A, Min), As). ?- find_min_2(Min, As). Min = 2, As = [b, e, h]. NB This only gives the