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In this work we present the concept of amenable $C$-semianalytic subset of a real analytic manifold $M$ and study the main properties of this type of sets. Amenable $C$-semianalytic sets can be understood as globally defined semianalytic…

Algebraic Geometry · Mathematics 2015-11-24 José F. Fernando

We give an example of a real algebraic manifold embedded in a complex space that does not satisfy the Nash-Artin approximation Property. This Nash-Artin approximation Property is closely related to the problem of determining when the…

Complex Variables · Mathematics 2019-09-20 Guillaume Rond

In this work we compare the semialgebraic subsets that are images of regulous maps with those that are images of regular maps. Recall that a map f : R n $\rightarrow$ R m is regulous if it is a rational map that admits a continuous…

Algebraic Geometry · Mathematics 2017-11-29 José Fernando , Goulwen Fichou , Ronan Quarez , Carlos Ueno

We characterize locally injective semialgebraic maps between two semialgebraic sets in terms of the induced homomorphism between their rings of (continuous) semialgebraic functions.

Algebraic Geometry · Mathematics 2025-04-17 E. Baro , J. F. Fernando , J. M. Gamboa

A set $S\subseteq \re^n$ is called to be {\it Semidefinite (SDP)} representable if $S$ equals the projection of a set in higher dimensional space which is describable by some Linear Matrix Inequality (LMI). The contributions of this paper…

Optimization and Control · Mathematics 2008-12-08 J. William Helton , Jiawang Nie

Let $S =\{x\in \re^n: g_1(x)\geq 0, ..., g_m(x)\geq 0\}$ be a semialgebraic set defined by multivariate polynomials $g_i(x)$. Assume $S$ is convex, compact and has nonempty interior. Let $S_i =\{x\in \re^n: g_i(x)\geq 0\}$, and $\bdS$…

Optimization and Control · Mathematics 2008-07-21 J. William Helton , Jiawang Nie

We consider cylindrical algebraic decompositions (CADs) as a tool for representing semi-algebraic subsets of $\mathbb{R}^n$. In this framework, a CAD $\mathscr{C}$ is adapted to a given set $S$ if $S$ is a union of cells of $\mathscr{C}$.…

Symbolic Computation · Computer Science 2024-11-21 Lucas Michel , Pierre Mathonet , Naïm Zénaïdi

Bierstone and Parusi\'nski studied the desingularization of $d$-dimensional closed subanalytic sets and in particular of $d$-dimensional closed semialgebraic sets. Their main tools are Hironaka's desingularization of real algebraic sets (to…

Algebraic Geometry · Mathematics 2026-01-19 Antonio Carbone , José F. Fernando

A semi-algebraic set is a subset of the real space defined by polynomial equations and inequalities having real coefficients and is a union of finitely many maximally connected components. We consider the problem of deciding whether two…

Algebraic Geometry · Mathematics 2020-11-16 Hoon Hong , James Rohal , Mohab Safey El Din , Eric Schost

The purpose of this paper is to define semi- and subanalytic subsets and maps in the context of real analytic orbifolds and to study their basic properties. We prove results analogous to some well-known results in the manifold case. For…

Geometric Topology · Mathematics 2011-04-26 Marja Kankaanrinta

In this article, we present a novel theory of locally semialgebraic superspaces along with Nash supermanifolds. By adapting Batchelor's theorem to our framework, we show that all locally semialgebraic superspaces and affine Nash…

Algebraic Geometry · Mathematics 2023-10-27 Mahir Bilen Can

Let $\mathcal S$ be a semigroup of partial isometries acting on a complex, infinite-dimensional, separable Hilbert space. In this paper we seek criteria which will guarantee that the selfadjoint semigroup $\mathcal T$ generated by $\mathcal…

Operator Algebras · Mathematics 2014-11-21 Janez Bernik , Laurent W. Marcoux , Alexey I. Popov , Heydar Radjavi

The Semialgebraic Orbit Problem is a fundamental reachability question that arises in the analysis of discrete-time linear dynamical systems such as automata, Markov chains, recurrence sequences, and linear while loops. An instance of the…

Computational Complexity · Computer Science 2019-02-01 Shaull Almagor , Joël Oukanine , James Worrell

This paper is, in a first stage, devoted to establish a topological--algebraic characterization of the principal component, $\mathcal{U}^0 (M)$, of the set of unitary elements, $\mathcal{U} (M)$, in a unital JB$^*$-algebra $M$. We arrive to…

Operator Algebras · Mathematics 2021-06-01 María Cueto-Avellaneda , Yuta Enami , Daisuke Hirota , Takeshi Miura , Antonio M. Peralta

Based on a recently developed rank Theorem for Eisenstein power series, we provide new proofs of the following two results of W. Pawlucki: I) The non regular locus of a complex or real analytic map is an analytic set. II) The set of…

Algebraic Geometry · Mathematics 2023-03-15 Andre Belotto da Silva , Octave Curmi , Guillaume Rond

We present new real algebraic maps of non-positive codimensions with prescribed images whose boundaries consist of explicit non-singular real algebraic hypersurfaces satisfying so-called "transversality" as follows. Explicit information on…

Algebraic Geometry · Mathematics 2024-09-17 Naoki Kitazawa

We prove that two infinite p-adic semi-algebraic sets are isomorphic (i.e. there exists a semi-algebraic bijection between them) if and only if they have the same dimension.

Logic · Mathematics 2007-05-23 Raf Cluckers

We study the structure of separable elements in bipartite C$^{\ast}$-algebras, focusing on the existence and size of a separable neighbourhood around the identity element. While this phenomenon is well understood in the finite-dimensional…

Operator Algebras · Mathematics 2026-04-02 Mizanur Rahaman , Mateusz Wasilewski

Let X be a normal connected complex algebraic variety equipped with a semisimple complex representation of its fundamental group. Then, under a maximality assumption, we prove that the covering space of X associated to the kernel of the…

Algebraic Geometry · Mathematics 2023-05-18 Yohan Brunebarbe

In the present paper we consider the problem of the existence of pre-semigeodesic coordinates on manifolds with affine connection. We proved that pre-semigeodesic coordinates exist in the case when the components of the affine connection…

Differential Geometry · Mathematics 2016-08-29 Irena Hinterleitner , Josef Mikeš