English

New Ideas for Resolution of Singularities in Arbitrary Characteristic

Algebraic Geometry 2010-11-05 v1

Abstract

Let kk be \emph{any} algebraically closed field in any characteristic, let RR be any regular local ring such that RR contains kk as a subring, the residue field of RR is isomorphic to kk as kk-algebras and dimR1\dim R\geq 1, let PP be any parameter system of RR and let zPz\in P. We consider any ϕR\phi\in R with ϕ0\phi\neq 0. In our main theorem we assume several conditions depending on PP, zz and Newton polyhedrons. By our assumptions the normal fan Σ\Sigma of the Newton polyhedron Γ+(P,ϕ)\Gamma_+(P,\phi) of ϕ\phi over PP has simple structure and we can make a special regular subdivision Σ\Sigma^* of Σ\Sigma called an upward subdivision, starting from a regular cone with dimension equal to dimR\dim R and repeating star subdivisions with center in a regular cone of dimension two. Let XX and σ:X\Spec(R)\sigma:X\rightarrow\Spec(R) denote the toric variety over \Spec(R)\Spec(R) and the toric morphism associated with Σ\Sigma^*. We consider any closed point aXa\in X such that σ(a)\sigma(a) is the unique closed point of \Spec(R)\Spec(R) and the morphism σ:ROX,a\sigma^*: R \rightarrow\mathcal{O}_{X,a} of local kk-algebras induced by σ\sigma. We show that our numerical invariant of σ(ϕ)OX,a\sigma^*(\phi)\in \mathcal{O}_{X,a} measuring the badness of the singularity is strictly less than the same invariant of ϕR\phi\in R and the singularity ϕ\phi is strictly improved by σ\sigma. We notice that this result opens a way toward the theory of resolution of singularities in arbitrary characteristic. We add several submain theorems to make bridges toward it and to show that our assumptions of the main theorem are not strong. By these results we can show that in a mathematical game with two players A and B related to the resolution of singularities of ϕ\phi, the player A can always win the game after finite steps. It follows "the local uniformization theorem in arbitrary characteristic and in arbitrary dimension".

Keywords

Cite

@article{arxiv.1011.1083,
  title  = {New Ideas for Resolution of Singularities in Arbitrary Characteristic},
  author = {Tohsuke Urabe},
  journal= {arXiv preprint arXiv:1011.1083},
  year   = {2010}
}

Comments

This is the third version of arXiv:1004.5446, and has a new abstract, a new introduction and a lot of new descriptions. In the third version I would like to delete the strange "s" at the end of the title of previous versions. However, I have found that the arXiv server computer does not accept the submission as the third version, if I delete only one character "s" at the end of the title