Editing Prolog (section)

=== Constraints ===
[[Constraint logic programming]] extends Prolog to include concepts from [[constraint satisfaction]].<ref>{{Cite journal |last=Jaffar |first=J. |year=1994 |title=Constraint logic programming: a survey |journal=The Journal of Logic Programming |volume=19–20 |pages=503–581 |doi=10.1016/0743-1066(94)90033-7 |doi-access=free}}</ref><ref>
{{cite journal
 |first=Alain
 |last=Colmerauer |year=1987
 |title=Opening the Prolog III Universe
 |journal=Byte
 |volume=August
}}</ref> A constraint logic program allows constraints in the body of clauses, such as: <code>A(X,Y) :- X+Y>0.</code> It is suited to large-scale [[combinatorial optimisation]] problems<ref>{{Cite book |last=Wallace |first=M. |year=2002 |chapter=Constraint Logic Programming |isbn=978-3-540-45628-5 |title=Computational Logic: Logic Programming and Beyond |series=Lecture Notes in Computer Science |volume=2407 |pages=512–556 |doi=10.1007/3-540-45628-7_19}}</ref> and is thus useful for applications in industrial settings, such as automated time-tabling and [[production scheduling]]. Most Prolog systems ship with at least one constraint solver for finite domains, and often also with solvers for other domains like [[rational number]]s.