# Hypergraph

### From Glossary

A set of *nodes* (or
*vertices*), say V, plus a set of *edges*, say E, such
that each member of E is a subset of V. When each member of E has
exactly 2 nodes, [V,E] is a graph. The hypergraph is a
convenient mathematical way to describe relations that involve more
than two objects (nodes).

Specific cases:

- An IIS hypergraph: each node represents an inequality and each edge represents an IIS.
- A common graphical representation of non-binary constraint networks is as a hypergraph, where nodes represent variables and edges group variables together that belong to the same scope.