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An action of a group on a vector space partitions the latter into a set of orbits. We consider three natural and useful algorithmic "isomorphism" or "classification" problems, namely, orbit equality, orbit closure intersection, and orbit…

Data Structures and Algorithms · Computer Science 2021-10-22 Peter Bürgisser , M. Levent Doğan , Visu Makam , Michael Walter , Avi Wigderson

We present an explicit formula for the topology and H-flux of the T-dual of a general type II compactification, significantly generalizing earlier results. Our results apply to T-dualities with respect to any circle action on spacetime. As…

High Energy Physics - Theory · Physics 2012-11-06 Varghese Mathai , Siye Wu

Using elementary graded automorphisms of polytopal algebras (essentially the coordinate rings of projective toric varieties) polyhedral versions of the group of elementary matrices and the Steinberg and Milnor groups are defined. They…

K-Theory and Homology · Mathematics 2007-05-23 Winfried Bruns , Joseph Gubeladze

We describe the basic Dolbealut cohomology algebra of the canonical foliation on a class of complex manifolds with a torus symmetry group. This class includes complex moment-angle manifolds, LVM- and LVMB-manifolds and, in most generality,…

Differential Geometry · Mathematics 2021-09-02 Roman Krutowski , Taras Panov

We consider a Hamiltonian action of n-dimensional torus, T^n, on a compact symplectic manifold (M,\omega) with d isolated fixed points. For every fixed point p there exists (though not unique) a class a_p in H^*_{T}(M; Q) such that the…

Symplectic Geometry · Mathematics 2013-01-23 Milena Pabiniak

The purpose of this paper is the formal verification of a counterexample of Santos et al. to the so-called Hirsch Conjecture on the diameter of polytopes (bounded convex polyhedra). In contrast with the pen-and-paper proof, our approach is…

Logic in Computer Science · Computer Science 2023-01-11 Xavier Allamigeon , Quentin Canu , Pierre-Yves Strub

The bifurcation sets of polynomial functions have been studied by many mathematicians from various points of view. In particular, N\'emethi and Zaharia described them in terms of Newton polytopes. In this paper, we will show analogous…

Algebraic Geometry · Mathematics 2020-12-29 Tat Thang Nguyen , Takahiro Saito , Kiyoshi Takeuchi

Hypersimplices are well-studied objects in combinatorics, optimization, and representation theory. For each hypersimplex, we define a new family of subpolytopes, called r-stable hypersimplices, and show that a well-known regular unimodular…

Combinatorics · Mathematics 2016-03-17 Benjamin Braun , Liam Solus

The Ehrhart quasipolynomial of a rational polytope $P$ encodes the number of integer lattice points in dilates of $P$, and the $h^*$-polynomial of $P$ is the numerator of the accompanying generating function. We provide two decomposition…

Combinatorics · Mathematics 2024-09-24 Matthias Beck , Benjamin Braun , Andrés R. Vindas-Meléndez

We consider an effective action of a compact (n-1)-torus on a smooth 2n-manifold with isolated fixed points. We prove that under certain conditions the orbit space is a closed topological manifold. In particular, this holds for certain…

Algebraic Topology · Mathematics 2019-03-11 Anton Ayzenberg

We present a polynomial time algorithm to compute any fixed number of the highest coefficients of the Ehrhart quasi-polynomial of a rational simplex. Previously such algorithms were known for integer simplices and for rational polytopes of…

Combinatorics · Mathematics 2007-05-23 Alexander Barvinok

A seminal result of E. Ehrhart states that the number of integer lattice points in the dilation of a rational polytope by a positive integer $k$ is a quasi-polynomial function of $k$ --- that is, a "polynomial" in which the coefficients are…

Combinatorics · Mathematics 2020-02-11 Tyrrell B. McAllister

We introduce the notion of doubling and r-tupling for simplicial complexes, a notion reminiscent to that of matching complexes in graph theory. We prove a connectivity result for such complexes and relate r-tupling to stabilizing r times…

Combinatorics · Mathematics 2025-06-13 Kathryn Lesh , Bridget Schreiner , Nathalie Wahl

A simple polytope $P$ is called $B$-rigid if its combinatorial type is determined by the cohomology ring of the moment-angle manifold $\mathcal{Z}_P$ over $P$. We show that any tensor product decomposition of this cohomology ring is…

Algebraic Topology · Mathematics 2022-05-03 Steven Amelotte , Benjamin Briggs

We show that the Kontsevich operad, as an operad with multiplication, provides a model for the Taylor tower of the functor defined by taking the homotopy fiber of the inclusion of embeddings of an interval in a cube to the corresponding…

Algebraic Topology · Mathematics 2007-05-23 Dev Sinha

Let G be a torus of dimension n > 1 and M a compact Hamiltonian G-manifold with $M^G$ finite. A circle, $S^1$, in G is generic if $M^G = M^{S^1}$. For such a circle the moment map associated with its action on M is a perfect Morse function.…

Symplectic Geometry · Mathematics 2007-05-23 Victor Guillemin , Catalin Zara

In this paper, we introduce and analyze a new iterative algorithm for solving a class of variational inclusions involving H-monotone operators. The strong convergence of this algorithm is proved and estimate of its convergence rate is…

Functional Analysis · Mathematics 2015-01-15 Faik Gursoy

We study a class of smooth torus manifolds whose orbit space has the combinatorial structure of a simple polytope with holes. We construct moment angle manifolds for such polytopes with holes and use them to prove that the associated torus…

Symplectic Geometry · Mathematics 2024-12-05 Mainak Poddar , Soumen Sarkar

The Fourier transforms of polyhedral cones can be used, via Brion's theorem, to compute various geometric quantities of polytopes, such as volumes, moments, and lattice-point counts. We present a novel method of computing these conic…

Combinatorics · Mathematics 2018-08-02 Quang-Nhat Le

We present two algorithms that compute the Newton polytope of a polynomial defining a hypersurface H in C^n using numerical computation. The first algorithm assumes that we may only compute values of f - this may occur if f is given as a…

Algebraic Geometry · Mathematics 2012-10-11 Jonathan D. Hauenstein , Frank Sottile