rational variety

A $n$-dimensional algebraic $k$-variety $M$ is **rational** if there is a birational map $M\to P^n_k$ to the projective space. A variety is irrational if it is not rational. It is often a difficult question wheather some concrete example of a variety is rational.

Revised on May 19, 2010 18:27:58
by Zoran Škoda
(161.53.130.104)