Rational connectivity and analytic contractibility

Autor: Morgan V. Brown, Tyler Foster
Rok vydání: 2016
Předmět:
Zdroj: Journal für die reine und angewandte Mathematik (Crelles Journal). 2019:45-62
ISSN: 1435-5345
0075-4102
DOI: 10.1515/crelle-2016-0019
Popis: Let k {{k}} be an algebraically closed field of characteristic 0, and let f : X → Y {f:X\to Y} be a morphism of smooth projective varieties over the ring k ⁢ ( ( t ) ) {k((t))} of formal Laurent series. We prove that if a general geometric fiber of f is rationally connected, then the induced map f an : X an → Y an {f^{\mathrm{an}}:X^{\mathrm{an}}\to Y^{\mathrm{an}}} between the Berkovich analytifications of X and Y is a homotopy equivalence. Two important consequences of this result are that the Berkovich analytification of any ℙ n {\mathbb{P}^{n}} -bundle over a smooth projective k ⁢ ( ( t ) ) {k((t))} -variety is homotopy equivalent to the Berkovich analytification of the base, and that the Berkovich analytification of a rationally connected smooth projective variety over k ⁢ ( ( t ) ) {k((t))} is contractible.
Databáze: OpenAIRE