# Global constraint

### From Glossary

A global constraint is a family of scope-parameterized constraints (normally ), where is the size of the scope of the constraint. The relation represented by the constraint is often defined implicitly (i.e., intensionally) via a compact set of characteristics that all satisfying tuples must exhibit. For example, the all-different constraint is satisfied by all assignments to its variables where no pair have the same value. Such implicit definitions are then expressed and enforced by the constraint propagator corresponding to the global constraint.

Global constraint may also be explicitly (i.e., extensionally) defined by providing a set of satisfying (or non-satisfying) tuples.

The most common global constraint are: