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A notion of rigidity with respect to an arbitrary semidualizing complex C over a commutative noetherian ring R is introduced and studied. One of the main result characterizes C-rigid complexes. Specialized to the case when C is the relative…

Commutative Algebra · Mathematics 2009-09-15 Luchezar L. Avramov , Srikanth B. Iyengar , Joseph Lipman

Design matrices are sparse matrices in which the supports of different columns intersect in a few positions. Such matrices come up naturally when studying problems involving point sets with many collinear triples. In this work we consider…

Combinatorics · Mathematics 2018-03-13 Zeev Dvir , Ankit Garg , Rafael Oliveira , József Solymosi

This paper introduces the notion of weak rigidity to characterize a framework by pairwise inner products of inter-agent displacements. Compared to distance-based rigidity, weak rigidity requires fewer constrained edges in the graph to…

Systems and Control · Computer Science 2018-04-10 Gangshan Jing , Guofeng Zhang , Heung Wing Joseph Lee , Long Wang

The Constant Degree Hypothesis was introduced by Barrington et. al. (1990) to study some extensions of $q$-groups by nilpotent groups and the power of these groups in a certain computational model. In its simplest formulation, it…

Computational Complexity · Computer Science 2023-11-30 Piotr Kawałek , Armin Weiß

Hadamard matrices are $(-1, +1)$ square matrices with mutually orthogonal rows. The Hadamard conjecture states that Hadamard matrices of order $n$ exist whenever $n$ is $1$, $2$, or a multiple of $4$. However, no construction is known that…

Combinatorics · Mathematics 2023-06-30 Matteo Cati , Dmitrii V. Pasechnik

The show that the upper-left-corner problem and upper-right-corner problem for matrix groups with rational entries are undecidable. To reach this aim, we answer a question of Dixon from 1985 by proving the undecidability of the stabilizer…

Group Theory · Mathematics 2024-03-25 Emmanuel Breuillard , Georgi Kocharyan

Komj\'ath, Milner, and Polat investigated when a finitary matroid admits a partition into circuits. They defined the class of ``finite matching extendable'' matroids and showed in their compactness theorem that those matroids always admit…

Combinatorics · Mathematics 2025-09-17 Nathan Bowler , Attila Joó

Tubal scalars are usual vectors, and tubal matrices are matrices with every element being a tubal scalar. Such a matrix is often recognized as a third-order tensor. The product between tubal scalars, tubal vectors, and tubal matrices can be…

Spectral Theory · Mathematics 2021-07-28 Yuning Yang , Junwei Zhang

The goal of this paper is to establish that it remains undecidable whether a sequent is provable in two systems in which a weakening rule for an exponential modality is completely omitted from classical propositional linear logic…

Logic in Computer Science · Computer Science 2025-09-03 Jun Suzuki , Katsuhiko Sano

Combinatorial rigidity theory seeks to describe the rigidity or flexibility of bar-joint frameworks in R^d in terms of the structure of the underlying graph G. The goal of this article is to broaden the foundations of combinatorial rigidity…

Combinatorics · Mathematics 2011-10-05 Mike Develin , Jeremy L. Martin , Victor Reiner

We prove super-polynomial lower bounds for low-depth arithmetic circuits using the shifted partials measure [Gupta-Kamath-Kayal-Saptharishi, CCC 2013], [Kayal, ECCC 2012] and the affine projections of partials measure [Garg-Kayal-Saha, FOCS…

Computational Complexity · Computer Science 2022-11-16 Prashanth Amireddy , Ankit Garg , Neeraj Kayal , Chandan Saha , Bhargav Thankey

We characterize the combinatorial types of symmetric frameworks in the plane that are minimally generically symmetry-forced infinitesimally rigid when the symmetry group consists of rotations and translations. Along the way, we use tropical…

Combinatorics · Mathematics 2021-12-09 Daniel Irving Bernstein

Border complexity measures are defined via limits (or topological closures), so that any function which can approximated arbitrarily closely by low complexity functions itself has low border complexity. Debordering is the task of proving an…

Computational Complexity · Computer Science 2024-11-11 Pranjal Dutta , Fulvio Gesmundo , Christian Ikenmeyer , Gorav Jindal , Vladimir Lysikov

In this article, we consider a special class of Williamson type matrices which we call them near Williamson matrices. They are in fact four $n\times n$ $(-1, 1)$-matrices $A, B, C, D$ so that $A$ is circulant, $B,C,D$ are symmetric…

Combinatorics · Mathematics 2026-05-12 Hadi Kharaghani , Ali Mohammadian , Behruz Tayfeh-Rezaie

We investigate the complexity of computing the Zariski closure of a finitely generated group of matrices. The Zariski closure was previously shown to be computable by Derksen, Jeandel, and Koiran, but the termination argument for their…

Computational Complexity · Computer Science 2025-03-05 Klara Nosan , Amaury Pouly , Sylvain Schmitz , Mahsa Shirmohammadi , James Worrell

We study $m \times n$ matrices whose columns are of the form \[\{(a_{1j},\ldots, a_{nj}): \quad a_{1j} = \lambda_j,\ a_{ij} = \pm\lambda_j\ , \ \lambda_j >0 ,\ j=1,2,\ldots,n\}.\] We explicitly construct for all $a = (a_1,\ldots,…

Combinatorics · Mathematics 2023-03-23 Sara Botelho-Andrade , Peter G. Casazza , Desai Cheng , Tin Tran , Janet Tremain

Nonnegative matrix factorizations are often encountered in data mining applications where they are used to explain datasets by a small number of parts. For many of these applications it is desirable that there exists a unique nonnegative…

Algebraic Geometry · Mathematics 2020-09-02 Robert Krone , Kaie Kubjas

Motivated by a rigidity-theoretic perspective on the Localization Problem in 2D, we develop an algorithm for computing circuit polynomials in the algebraic rigidity matroid associated to the Cayley-Menger ideal for $n$ points in 2D. We…

Combinatorics · Mathematics 2021-03-17 Goran Malić , Ileana Streinu

The work on the estimation of the condition numbers of Vandermonde matrices, motivated by applications to interpolation and quadrature, can be traced back at least to the 1970s. Empirical study has shown consistently that Vandermonde…

Numerical Analysis · Mathematics 2015-07-13 Victor Y. Pan

The problem of constructing or characterizing strongly regular Cayley graphs (or equivalently, regular partial difference sets) has garnered significant attention over the past half-century. In 2003, Miklavi\v{c} and Poto\v{c}nik [European…

Combinatorics · Mathematics 2025-02-14 Xiongfeng Zhan , Xueyi Huang , Lu Lu