On a theorem of Faltings on formal functions

  • Paola Bonacini Università degli Studi di Catania
  • Alessio Del Padrone Università degli Studi di Genova
  • Michele Nesci Università degli Studi Roma Tre

Abstract

In 1980, Faltings proved, by deep local algebra methods, a local result
regarding formal functions which has the following global geometric fact
as a consequence. Theorem. − Let k be an algebraically closed field (of
any characteristic). Let Y be a closed subvariety of a projective irreducible
variety X defined over k. Assume that X ⊂ P^n , dim(X) = d > 2 and Y
is the intersection of X with r hyperplanes of P^n , with r ≤ d − 1. Then,
every formal rational function on X along Y can be (uniquely) extended to
a rational function on X . Due to its importance, the aim of this paper is to
provide two elementary global geometric proofs of this theorem.

Author Biographies

Paola Bonacini, Università degli Studi di Catania
Dipartimento di Matematica e Informatica
Viale A. Doria, 6 - 95124 Catania
Alessio Del Padrone, Università degli Studi di Genova
Dipartimento di Matematica
Via Dodecaneso, 35 - 16146 Genova
Michele Nesci, Università degli Studi Roma Tre
Dipartimento di Matematica
Largo Leonardo Murialdo, 1 - 00146 Roma
Published
2007-12-05
Section
Articoli