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 the variety is unirational or not, then to decide weather it is rational or not.

Created on May 19, 2010 18:27:12 by Zoran Škoda (161.53.130.104)