On a theorem of Faltings on formal functions

Authors

  • 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

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Published

2007-12-05

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Section

Articoli