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We describe new algorithms to compute Whitney stratifications of real algebraic varieties. Using either conormal or polar techniques, these algorithms stratify a complexification of a given real variety. We then show that the resulting…

Algebraic Geometry · Mathematics 2025-09-03 Martin Helmer , Anton Leykin , Vidit Nanda

We describe two new algorithms for the computation of Whitney stratifications of real and complex algebraic varieties. The first algorithm is a modification of the algorithm of Helmer and Nanda (HN), but is made more efficient by using…

Algebraic Geometry · Mathematics 2025-12-01 Martin Helmer , Rafael Mohr

Algebraic boundaries of convex semi-algebraic sets are closely related to polynomial optimization problems. Building upon Rainer Sinn's work, we refine the stratification of iterated singular loci to a Whitney (a) stratification, which…

Optimization and Control · Mathematics 2024-06-10 Zihao Dai , Zijia Li , Zhi-Hong Yang , Lihong Zhi

We prove a combinatorial version of Thom's Isotopy Lemma for projection maps applied to any complex or real toric variety. Our results are constructive and give rise to a method for associating the Whitney strata of the projection to the…

Algebraic Geometry · Mathematics 2024-08-20 Boulos El Hilany , Martin Helmer , Elias Tsigaridas

The method of Whitney interpolation is used to construct, for any real or complex projective algebraic variety, a stratified submersive family of self-maps that yields stratified general position and transversality theorems for…

Algebraic Geometry · Mathematics 2018-11-06 Clint McCrory , Adam Parusinski , Laurentiu Paunescu

We define "t-stratifications", a strong notion of stratifications for Henselian valued fields $K$ of equi-characteristic 0, and prove that they exist. In contrast to classical stratifications in Archimedean fields, t-stratifications also…

Algebraic Geometry · Mathematics 2014-08-26 Immanuel Halupczok

The generation of curves and surfaces from given data is a well-known problem in Computer-Aided Design that can be approached using subdivision schemes. They are powerful tools that allow obtaining new data from the initial one by means of…

Numerical Analysis · Mathematics 2024-12-03 Sergio López-Ureña , Dionisio F. Yáñez

We outline an algorithm to recover the canonical (or, coarsest) stratification of a given finite-dimensional regular CW complex into cohomology manifolds, each of which is a union of cells. The construction proceeds by iteratively…

Algebraic Topology · Mathematics 2019-06-18 Vidit Nanda

This paper proposes and develops a new Newton-type algorithm to solve subdifferential inclusions defined by subgradients of extended-real-valued prox-regular functions. The proposed algorithm is formulated in terms of the second-order…

Optimization and Control · Mathematics 2022-09-16 Pham Duy Khanh , Boris Mordukhovich , Vo Thanh Phat

We stratify families of projective and very affine hypersurfaces according to their topological Euler characteristic. Our new algorithms compute all strata using algebro-geometric techniques. For very affine hypersurfaces, we investigate…

Algebraic Geometry · Mathematics 2024-07-26 Simon Telen , Maximilian Wiesmann

We specify the canonical stratifications satisfying respectively Whitney (a)-regularity, Whitney (b)-regularity, Kuo-Verdier (w)-regularity, and Mostowski (L)-regularity for the family of surfaces y^a = t^b x^c + x^d, where a, b, c, d are…

Algebraic Geometry · Mathematics 2017-01-19 Dwi Juniati , Laurent Noirel , David Trotman

We investigate a scheme-theoretic variant of Whitney condition a. If X is a projec-tive variety over the field of complex numbers and Y $\subset$ X a subvariety, then X satisfies generically the scheme-theoretic Whitney condition a along Y…

Algebraic Geometry · Mathematics 2018-11-26 Roland Abuaf

X-ray computed tomographic infrastructures are medical imaging modalities that rely on the acquisition of rays crossing examined objects while measuring their intensity decrease. Physical measurements are post-processed by mathematical…

Image and Video Processing · Electrical Eng. & Systems 2022-01-25 Attila Juhos

Closed subschemes in projective space with a fixed Hilbert polynomial are parametrized by a Hilbert scheme. We classify the smooth ones. We identify numerical conditions on a polynomial that completely determine when the Hilbert scheme is…

Algebraic Geometry · Mathematics 2023-01-13 Roy Skjelnes , Gregory G. Smith

The linear optimization degree gives an algebraic measure of complexity of optimizing a linear objective function over an algebraic model. Geometrically, it can be interpreted as the degree of a projection map on the {affine} conormal…

Algebraic Geometry · Mathematics 2023-04-25 Laurentiu G. Maxim , Jose Israel Rodriguez , Botong Wang , Lei Wu

Here we define a new unification algorithm for terms interpreted in semantic domains denoted by a subclass of regular types here called deterministic regular types. This reflects our intention not to handle the semantic universe as a…

Logic in Computer Science · Computer Science 2025-02-14 João Barbosa , Mário Florido , Vítor Santos Costa

We provide a computationally and statistically efficient method for estimating the parameters of a stochastic covariance model observed on a regular spatial grid in any number of dimensions. Our proposed method, which we call the Debiased…

Methodology · Statistics 2022-04-27 Arthur P. Guillaumin , Adam M. Sykulski , Sofia C. Olhede , Frederik J. Simons

Fine-grained image recognition is very challenging due to the difficulty of capturing both semantic global features and discriminative local features. Meanwhile, these two features are not easy to be integrated, which are even conflicting…

Computer Vision and Pattern Recognition · Computer Science 2021-02-22 Shaokang Yang , Shuai Liu , Cheng Yang , Changhu Wang

We propose an efficient estimation technique for the automatic selection of locally-adaptive Total Variation regularisation parameters based on an hybrid strategy which combines a local maximum-likelihood approach estimating space-variant…

Optimization and Control · Mathematics 2020-05-20 Luca Calatroni , Alessandro Lanza , Monica Pragliola , Fiorella Sgallari

In this paper we show Whitney's fibering conjecture in the real and complex, local analytic and global algebraic cases. For a given germ of complex or real analytic set, we show the existence of a stratification satisfying a strong (real…

Algebraic Geometry · Mathematics 2017-01-25 Adam Parusiński , Laurentiu Paunescu
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