Simultaneous resolution of singularities

We prove a local theorem on simultaneous resolution of singularities, which is valid in all dimensions. This theorem is proven in dimension 2 (and in all characteristics) by Abhyankar in his book ``Ramification theoretic methods in algebraic geometry' (1959).

     

Simultaneous algorithmic resolution of singularities

This paper studies the concept of algorithmic equiresolution of a family of embedded varieties or ideals, which means a simultaneous resolution of such a family compatible with a given (suitable) algorithm of resolution in characteristic zero. The paper’s approach is more indirect: it primarily considers the more general case of families of basic objects (or marked ideals). A definition of algorithmic equiresolution is proposed, which applies to families whose parameter space T may be non-reduced, e.g., the spectrum of a suitable artinian ring. Other definitions of algorithmic equiresolution are also discussed. These are geometrically very natural, but the parameter space T of the family must be assumed regular. It is proven that when T is regular all the proposed definitions are equivalent.     

Newton polyhedra (resolution of singularities)

Some results are presented on the resolution of singularities and compactification of an algebraic manifold determined by a system of algebraic equations with fixed Newton polyhedra and rather general coefficients. Resolution and compactification are carried out by means of smooth toric manifolds which are described in the first half of the survey.Translated from Itogi Nauki i Tekhniki, Seriya Sovremennye Problemy Matematiki, Vol. 22, pp. 207–239, 1983.     

An elementary coordinate-dependent local resolution of singularities and applications

An elementary classical analysis resolution of singularities method is developed, extensively using explicit coordinate systems. The algorithm is designed to be applicable to subjects such as oscillatory integrals and critical integrability exponents. As one might expect, the trade-off for such an elementary method is a weaker theorem than Hironaka's work [H. Hironaka, Resolution of singularities of an algebraic variety over a field of characteristic zero I, Ann. of Math. (2) 79 (1964) 109-203; H. Hironaka, Resolution of singularities of an algebraic variety over a field of characteristic zero II, Ann. of Math. (2) 79 (1964) 205-326] or its subsequent simplications and extensions such as [E. Bierstone, P. Milman, Canonical desingularization in characteristic zero by blowing up the maximum strata of a local invariant, Invent. Math. 128 (2) (1997) 207-302; S. Encinas, O. Villamayor, Good points and constructive resolution of singularities, Acta Math. 181 (1) (1998) 109-158; J. Kollar, Resolution of singularities—Seattle lectures, preprint; A.N. Varchenko, Newton polyhedra and estimates of oscillatory integrals, Funct. Anal. Appl. 18 (3) (1976) 175-196]. Nonetheless the methods of this paper can be used to prove a variety of theorems of interest in analysis. As illustration, two consequences are given. First and most notably, a general theorem regarding the existence of critical integrability exponents are established. Secondly, a quick proof of a well-known inequality of Lojasiewicz [S. Lojasiewicz, Ensembles semi-analytiques, Inst. Hautes Études Sci., Bures-sur-Yvette, 1964] is given. The arguments here are substantially different from the general algorithms such as [H. Hironaka, Resolution of singularities of an algebraic variety over a field of characteristic zero I, Ann. of Math. (2) 79 (1964) 109-203; H. Hironaka, Resolution of singularities of an algebraic variety over a field of characteristic zero II, Ann. of Math. (2) 79 (1964) 205-326], or the elementary arguments of [E. Bierstone, P. Milman, Semianalytic and subanalytic sets, Inst. Hautes Études Sci. Publ. Math. 67 (1988) 5-42] and [H. Sussman, Real analytic desingularization and subanalytic sets: an elementary approach, Trans. Amer. Math. Soc. 317 (2) (1990) 417-461]. The methods here have as antecedents the earlier work of the author [M. Greenblatt, A direct resolution of singularities for functions of two variables with applications to analysis, J. Anal. Math. 92 (2004) 233-257], Phong and Stein [D.H. Phong, E.M. Stein, The Newton polyhedron and oscillatory integral operators, Acta Math. 179 (1997) 107-152], and Varchenko [A.N. Varchenko, Newton polyhedra and estimates of oscillatory integrals, Funct. Anal. Appl. 18 (3) (1976) 175-196].     

A note on resolution of rational and hypersurface singularities

It is well known that the exceptional set in a resolution of a rational surface singularity is a tree of rational curves. We generalize the combinatoric part of this statement to higher dimensions and show that the highest cohomologies of the dual complex associated to a resolution of an isolated rational singularity vanish. We also prove that the dual complex associated to a resolution of an isolated hypersurface singularity is simply connected. As a consequence, we show that the dual complex associated to a resolution of a 3-dimensional Gorenstein terminal singularity has the homotopy type of a point.

     

On the resolution of 3-dimensional terminal singularities

We show that there is at most one nonrational exceptional divisor with discrepancy 1 over a three-dimensional terminal point of type cD. If such a divisor exists, then it is birationally isomorphic to the surface ¹ × C, where C is a hyperelliptic (for g(C) > 1) curve.     

On the resolution of 3-dimensional terminal singularities

We show that there is at most one nonrational exceptional divisor with discrepancy 1 over a three-dimensional terminal point of type cD. If such a divisor exists, then it is birationally isomorphic to the surface ¹ × C, where C is a hyperelliptic (for g(C) > 1) curve.Translated from Matematicheskie Zametki, vol. 77, no. 1, 2005, pp. 127–140.Original Russian Text Copyright © 2005 by D. A. Stepanov.This revised version was published online in April 2005 with a corrected issue number.     

On the resolution of singularities of ordinary differential systems

We show how some differential geometric ideas help to resolve some singularities of ordinary differential systems. Hence a singular problem is replaced by a regular one, which facilitates further analysis of the system. The methods employed are constructive and the regularized systems can also be used for numerical computations. This revised version was published online in June 2006 with corrections to the Cover Date.     

On crepant resolution of some hypersurface singularities and a criterion for UFD

In this article, we find some diagonal hypersurfaces that admit crepant resolutions. We also give a criterion for unique factorization domains.

     

A resolution theorem for absolutely isolated singularities of holomorphic vector fields

In this paper, the desingularization problem for an absolutely isolated singularity of an-dimensional holomorphic vector field is solved. Also, we exhibit final forms under blowing-up for this type of singularities.     

On the resolution of singularities in affine toric 3- varieties

Let $x_{\Sigma(\sigma)}=\ {\rm spec C[\check \sigma \cap Z}^{n}]$ be an affine toric variety given by the monoid algebra $\rm C[\check \sigma \cap Z^{n}]$ , $\check \sigma$ the negative dual cone of a lattice cone σ ? Rⁿ, Σ(σ) the fan consisting of the faces of σ. Assume XΣ(σ) to have only quotient singularities. For n = 3 we classify all pairs X_Σ′, X_Σ(σ) which occur in minimal models of equivariant resolutions Φ: X_Σ′ → - X_Σ(σ) sucn that the regular toric variety XΣ′ has Picard number at most 3.     

Enlargement procedure for resolution of singularities at simple singular solutions of nonlinear equations

Summary A solution of a nonlinear equation in Hilbert spaces is said to be a simple singular solution if the Fréchet derivative at the solution has one-dimensional kernel and cokernel. In this paper we present the enlargement procedure for resolution of singularities at simple singular solutions of nonlinear equations. Once singularities are resolved, we can compute accurately the singular solution by Newton's method. Conditions for which the procedure terminates in finite steps are given. In particular, if the equation defined in ⁿ is analytic and the simple singular solution is geometrically isolated, the procedure stops in finite steps, and we obtain the enlarged problem with an isolated solution. Numerical examples are given.This research is partially supported by Grant-in-Aid for Encouragment of Young Scientist No. 60740119, the Ministry of EducationDedicated to Professor Seiiti Huzino on his 60th birthday