Michael Temkin

Desingularization of quasi-excellent schemes in characteristic zero

Grothendieck proved in EGA IV that if any integral scheme of finite type over a locally noetherian scheme X admits a desingularization, then X is quasi-excellent, and conjectured that the converse is probably true. We prove this conjecture for noetherian schemes of characteristic zero. Namely, starting with the resolution of singularities for algebraic varieties of characteristic zero, we prove the resolution of singularities for noetherian quasi-excellent Q-schemes.

On local properties of non-Archimedean analytic spaces II

The non-Archimedean analytic spaces are studied. We extend to the general case notions and results defined earlier only for strictly analytic spaces. In particular, we prove that any strictly analytic space admits a unique rigid model.

Introduction to Berkovich Analytic Spaces

This paper presents an extended version of lecture notes for an introductory course on Berkovich analytic spaces that I gave in 2010 at Summer School “Berkovich spaces” at Institut de Mathematiques de Jussieu.

Relative Riemann-Zariski spaces

In this paper we study relative Riemann-Zariski spaces associated to a morphism of schemes and generalizing the classical Riemann-Zariski space of a field. We prove that similarly to the classical RZ spaces, the relative ones can be described either as projective limits of schemes in the category of locally ringed spaces or as certain spaces of valuations. We apply these spaces to prove the following two new results: a strong version of stable modification theorem for relative curves; a decomposition theorem which asserts that any separated morphism between quasi-compact and quasiseparated schemes factors as a composition of an affine morphism and a proper morphism. In particular, we obtain a new proof of Nagata’s compactification theorem.

Metrization of Differential Pluriforms on Berkovich Analytic Spaces

We introduce a general notion of a seminorm on sheaves of rings or modules and provide each sheaf of relative differential pluriforms on a Berkovich k-analytic space with a natural seminorm, called Kahler seminorm. If the residue field \(\tilde{k}\) is of characteristic zero and X is a quasi-smooth k-analytic space, then we show that the maximality locus of any global pluricanonical form is a PL subspace of X contained in the skeleton of any semistable formal model of X. This extends a result of Mustaţă and Nicaise, because the Kahler seminorm on pluricanonical forms coincides with the weight norm defined by Mustaţă and Nicaise when k is discretely valued and of residue characteristic zero.

Functorial desingularization over Q : boundaries and the embedded case

Our main result establishes functorial desingularization of noetherian quasi-excellent schemes over Q with ordered boundaries. A functorial embedded desingularization of quasi-excellent schemes of characteristic zero is deduced. Furthermore, a standard simple argument extends these results to other categories including, in particular, (equivariant) embedded desingularization of the following objects of characteristic zero: qe algebraic stacks, qe formal schemes, complex and non-archimedean analytic spaces. We also obtain a semistable reduction theorem for formal schemes.

Non-archimedean analytification of algebraic spaces

It is now a classical result that an algebraic space locally of finite type over

Berkovich spaces and tubular descent

\mathbf{C}

Ferrand pushouts for algebraic spaces

is analytifiable if and only if it is locally separated. In this paper we study non-archimedean analytifications of algebraic spaces. We construct a quotient for any etale non-archimedean analytic equivalence relation whose diagonal is a closed immersion, and deduce that any separated algebraic space locally of finite type over any non-archimedean field

Altered local uniformization of Berkovich spaces

k