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We obtain sequences of inclusion sets for the spectrum, essential spectrum, and pseudospectrum of banded, in general non-normal, matrices of finite or infinite size. Each inclusion set is the union of the pseudospectra of certain…

Spectral Theory · Mathematics 2023-06-21 Simon N. Chandler-Wilde , Ratchanikorn Chonchaiya , Marko Lindner

We describe examples showing the sharpness of Fujita's conjecture on adjoint bundles also in the general type case, and use these examples to formulate related bold conjectures on pluricanonical maps of varieties of general type.

Algebraic Geometry · Mathematics 2022-06-28 Fabrizio Catanese

In this article we study homotopes of finite-dimensional algebras (not necessarily, associative). In the case of associative algebras we study homotopes by methods of Category theory and give description of so-called well-tempered elements…

Rings and Algebras · Mathematics 2020-05-05 Ilya Zhdanovskiy

In light of Kim's conjecture on regular polytopes of dimension four, which is a generalization of Waring's problem, we establish asymptotic formulas for representing any sufficiently large integer as a sum of numbers in the form of those…

Number Theory · Mathematics 2024-12-19 Anji Dong , The Nguyen , Alexandru Zaharescu

Recently, Stull [18], [17] resolved a long-standing open problem posed by Lutz, on whether the set of effective Hausdorff dimensions of points on a straight line in $\mathbb{R}^2$ -- the effective dimension spectrum of the line -- contains…

General Mathematics · Mathematics 2026-05-15 Prajval Koul , Satyadev Nandakumar

We use the differential algebra of polytopes to explain the known remarkable relation of the combinatorics of the associahedra and permutohedra with the universal compositional and multiplicative inversion formulas for the formal power…

Combinatorics · Mathematics 2025-02-11 V. M. Buchstaber , A. P. Veselov

A (convex) polytope $P$ is said to be $2$-level if for every direction of hyperplanes which is facet-defining for $P$, the vertices of $P$ can be covered with two hyperplanes of that direction. The study of these polytopes is motivated by…

We introduce the simple extension complexity of a polytope P as the smallest number of facets of any simple (i.e., non-degenerate in the sense of linear programming) polytope which can be projected onto P. We devise a combinatorial method…

Combinatorics · Mathematics 2015-01-23 Volker Kaibel , Matthias Walter

Let $f\in\Sigma_{n,2d}$ be a sum of squares. The Gram spectrahedron of $f$ is a compact, convex set that parametrizes all sum of squares representations of $f$. Let $F\subseteq\mathrm{Gram}(f)$ be a face of its Gram spectrahedron. We are…

Algebraic Geometry · Mathematics 2020-08-25 Julian Vill

We characterize all the strongly monotypic polytopes. Hadwiger's conjecture for this class of polytopes is deduced from the characterization.

Combinatorics · Mathematics 2021-11-09 Vuong Bui

We establish a strong form of Littlewood's conjecture with inhomogeneous shifts, for a full-dimensional set of pairs of badly approximable numbers on a vertical line. We also prove a uniform assertion of this nature, generalising a strong…

Number Theory · Mathematics 2021-03-15 Sam Chow , Agamemnon Zafeiropoulos

With an explicit, algebraic indexing $(2,1)$-category, we develop an efficient homotopy theory of cyclonic objects: circle-equivariant objects relative to the family of finite subgroups. We construct an $\infty$-category of cyclotomic…

Algebraic Topology · Mathematics 2016-02-09 Clark Barwick , Saul Glasman

We present an overview of a theory of complex dimensions of self-similar fractal strings, and compare this theory to the theory of varieties over a finite field from the geometric and the dynamical point of view. Then we combine the several…

Number Theory · Mathematics 2007-05-23 Michel L. Lapidus , Machiel van Frankenhuijsen

A "spectral convex set" is a collection of symmetric matrices whose range of eigenvalues form a symmetric convex set. Spectral convex sets generalize the Schur-Horn orbitopes studied by Sanyal-Sottile-Sturmfels (2011). We study this class…

Metric Geometry · Mathematics 2025-02-12 Raman Sanyal , James Saunderson

We describe a new sequence of polytopes which characterize A_infinity maps from a topological monoid to an A_infinity space. Therefore each of these polytopes is a quotient of the corresponding multiplihedron. Later term(s) in our sequence…

Category Theory · Mathematics 2008-05-08 Stefan Forcey

We give a summary on spectral techniques for finite dimensional algebras and study its link to singularity theory. In particular, we offer a contribution to the categorification of the Milnor lattice of two-dimensional singularities through…

Representation Theory · Mathematics 2008-05-08 Helmut Lenzing , Jose Antonio de la Pena

We formulate a conjecture concerning spectral factorization of a class of trigonometric polynomials of two variables and prove it for special cases. Our method uses relations between the distribution of values of a polynomial of two…

Number Theory · Mathematics 2012-08-29 Wayne Lawton

For each object in a tensor triangulated category, we construct a natural continuous map from the object's support---a closed subset of the category's triangular spectrum---to the Zariski spectrum of a certain commutative ring of…

Category Theory · Mathematics 2013-09-17 Beren Sanders

We introduce a spectrum for arbitrary varieties. This generalizes the definition by Steenbrink for hypersurfaces. In the isolated complete intersection singularity case, it coincides with the one given by Ebeling and Steenbrink except for…

Algebraic Geometry · Mathematics 2007-05-30 Alexandru Dimca , Philippe Maisonobe , Morihiko Saito

Let $X\subset P^n$ be a complex projective manifold of degree $d$ and arbitrary dimension. The main result of this paper gives a classification of such manifolds (assumed moreover to be connected, non-degenerate and linearly normal) in case…

Algebraic Geometry · Mathematics 2007-05-23 Paltin Ionescu