# Dilatation

From Encyclopedia of Mathematics

An obsolete term used to denote special birational transformations. The modern term is monoidal transformation.

#### Comments

There are, however, also several non-obsolete meanings of the term, such as the dilatation (dilatation coefficient) $k(f,a)$ of a quasi-conformal mapping and the theory of (unitary) dilatations in operator theory, cf. Contraction and Contraction semi-group; cf. also Spectral set.

**How to Cite This Entry:**

Dilatation.

*Encyclopedia of Mathematics.*URL: http://encyclopediaofmath.org/index.php?title=Dilatation&oldid=31635

This article was adapted from an original article by V.A. Iskovskikh (originator), which appeared in Encyclopedia of Mathematics - ISBN 1402006098. See original article