2
votes
2answers
248 views

Rationally connected varieties and rational fibrations

Let $Y$ be a rationally connected variety over an algebraically closed field, and let $$\phi:X\dashrightarrow Y$$ be a rational fibration such that the general fiber of $\phi$ is rationally chain ...
6
votes
1answer
323 views

Proving a variety is not unirational

It is known that if a variety is unirational then it is rationally connected. However, there are no known examples of rationally connected varieties which are not unirational. In these notes, at the ...