Questions tagged [constraint-handling-rules]

A little test code with no particular meaning: :- use_module(library(chr)). :- chr_constraint foo/1, bar/1, anyone/2. foo(X) \ bar(Y) <=> anyone(X,Y). anyone(_,Y) <=> bar(Y) | writef("bar(%w) exists\n",[Y]). anyone(_,Y) <=> writef("bar(%w) does…

As an example. Suppose that everything which is red has value 5. I write the following: :- use_module(library(chr)). :- use_module(library(clpfd)). :- chr_type color ---> red ; blue. :- chr_constraint hasColor(?any, ?color). :- chr_constraint…

I was trying a simple program in SWI-Prolog using the CHR library. The responses to the queries are obvious to me, but the tracing baffled me. I started with only one rule. and(X,Y,Z) <=> Y = 0 | Z = 0. Tracing made sense ?- and(A,B,C). CHR: …

I am writing a constraint solver in Prolog that implements a simple logical formula: "(alive(A) and animal(A)) iff (awake(A) or asleep(A))". I found one way to implement it in Constraint Handling Rules, but it is much more verbose than the original…