Abstract
In a paper from 1992, Kollár, Miyaoka and Mori posed the following question: Given a proper flat morphism f: P → X with target a nonsingular curve and whose geometric generic fiber is rationally-connected, does it follow that f admits a regular section? In the case that the ground field is an algebraically-closed field of characteristic zero, this was answered affirmatively by Graber, Harris, and Starr using a topological argument. We prove that f admits a regular section when the ground field is an algebraically-closed field of arbitrary characteristic. The key ingredients in the proof are the following: (a) Proposition 2.1 which shows that after taking the reduced fiber product of f with a generically étale morphism π: Y → X, we may assume that the smooth locus of f intersects every geometric fiber, and (b) Proposition 1.1 which is a purely algebraic analogue of the "moving branch points" argument in Graber-Harris-Starr. The reader is cautioned that our definition of "separably rationally connected" differs slightly from the original definition.
| Original language | English |
|---|---|
| Pages (from-to) | 567-580 |
| Number of pages | 14 |
| Journal | American Journal of Mathematics |
| Volume | 125 |
| Issue number | 3 |
| State | Published - Jun 2003 |
Fingerprint
Dive into the research topics of 'Every rationally connected variety over the function field of a curve has a rational point'. Together they form a unique fingerprint.Cite this
- APA
- Author
- BIBTEX
- Harvard
- Standard
- RIS
- Vancouver