Free descriptions of convex sets

E Levin, V Chandrasekaran - arXiv preprint arXiv:2307.04230, 2023 - arxiv.org
Convex sets arising in a variety of applications are well-defined for every relevant
dimension. Examples include the simplex and the spectraplex that correspond, respectively …

[HTML][HTML] Linear slices of hyperbolic polynomials and positivity of symmetric polynomial functions

C Riener, R Schabert - Journal of Pure and Applied Algebra, 2024 - Elsevier
A real univariate polynomial of degree n is called hyperbolic if all of its n roots are on the real
line. Such polynomials appear quite naturally in different applications, for example, in …

Symmetric non-negative forms and sums of squares

G Blekherman, C Riener - Discrete & Computational Geometry, 2021 - Springer
We study symmetric non-negative forms and their relationship with symmetric sums of
squares. For a fixed number of variables n and degree 2 d, symmetric non-negative forms …

Positivstellens\" atze and Moment problems with Universal Quantifiers

X Hu, I Klep, J Nie - arXiv preprint arXiv:2401.12359, 2024 - arxiv.org
This paper studies Positivstellens\" atze and moment problems for sets that are given by
universal quantifiers. Let $ Q $ be a closed set and let $ g=(g_1,..., g_s) $ be a tuple of …

[HTML][HTML] Reflection groups and cones of sums of squares

S Debus, C Riener - Journal of Symbolic Computation, 2023 - Elsevier
We consider cones of real forms which are sums of squares and invariant under a (finite)
reflection group. Using the representation theory of these groups we are able to use the …

Computing critical points for invariant algebraic systems

JC Faugère, G Labahn, MS El Din, É Schost… - Journal of Symbolic …, 2023 - Elsevier
Let K be a field and (f 1,…, fs, ϕ) be multivariate polynomials in K [x 1,…, xn](with s< n) each
invariant under the action of S n, the group of permutations of {1,…, n}. We consider the …

Real root finding for equivariant semi-algebraic systems

C Riener, M Safey el Din - Proceedings of the 2018 ACM International …, 2018 - dl.acm.org
Let R be a real closed field. We consider basic semi-algebraic sets defined by n-variate
equations/inequalities of s symmetric polynomials and an equivariant family of polynomials …

Faster real root decision algorithm for symmetric polynomials

G Labahn, C Riener, M Safey El Din, É Schost… - Proceedings of the 2023 …, 2023 - dl.acm.org
In this paper, we consider the problem of deciding the existence of real solutions to a system
of polynomial equations having real coefficients, and which are invariant under the action of …

Noncommutative rational functions invariant under the action of a finite solvable group

I Klep, JE Pascoe, G Podlogar, J Volčič - Journal of Mathematical Analysis …, 2020 - Elsevier
This paper describes the structure of invariant skew fields for linear actions of finite solvable
groups on free skew fields in d generators. These invariant skew fields are always finitely …

Symmetric nonnegative forms and sums of squares

G Blekherman, C Riener - arXiv preprint arXiv:1205.3102, 2012 - arxiv.org
We study symmetric nonnegative forms and their relationship with symmetric sums of
squares. For a fixed number of variables $ n $ and degree $2 d $, symmetric nonnegative …