nLab
unirational variety

An algebraic variety XX over a field kk is unirational if there is a dominant rational map of varieties f:P k nXf : P^n_k \dashrightarrow X. The class of unirational varieties is a natural generalization of a class of rational varieties. Usually, it is much easier to decide if a variety is unirational or not, than it is to decide whether or not it is rational.

Revised on July 1, 2015 01:15:45 by Elliot? (99.232.1.13)