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In this paper, we focus on the positive definiteness and Hurwitz stability of interval tensors. First, we introduce auxiliary tensors $\mathcal{A}^z$ and establish equivalent conditions for the positive (semi-)definiteness of interval…

Optimization and Control · Mathematics 2025-09-16 Li Ye , Yisheng Song

We study almost Hermitian structures admitting a Hermitian connexion with totally skew-symmetric torsion or equivalently, those almost Hermitian structures with totally skew-symmetric Nijenhuis tensor. We investigate up to what extent the…

Differential Geometry · Mathematics 2007-09-11 Paul-Andi Nagy

In our previous paper in \cite{C}, we generalized the almost-Schur lemma of De Lellis and Topping for closed manifolds with nonnegative Rcci curvature to any closed manifolds. In this paper, we generalize the above results to symmetric…

Differential Geometry · Mathematics 2016-01-20 Xu Cheng

In particle physics, scalar potentials have to be bounded from below in order for the physics to make sense. The precise expressions of checking lower bound of scalar potentials are essential, which is an analytical expression of checking…

Optimization and Control · Mathematics 2022-02-09 Yisheng Song , Liqun Qi

Given tensors $T$ and $T'$ of order $k$ and $k'$ respectively, the tensor product $T \otimes T'$ is a tensor of order $k+k'$. It was recently shown that the tensor rank can be strictly submultiplicative under this operation…

Algebraic Geometry · Mathematics 2019-09-11 Edoardo Ballico , Alessandra Bernardi , Matthias Christandl , Fulvio Gesmundo

One of the fundamental problems in multilinear algebra, the minimum ratio between the spectral and Frobenius norms of tensors, has received considerable attention in recent years. While most values are unknown for real and complex tensors,…

Numerical Analysis · Mathematics 2022-06-17 Shengyu Cao , Simai He , Zhening Li , Zhen Wang

The purpose of the article is to generalize the concept of approximate Birkhoff-James orthogonality, in the semi-Hilbertian structure. Given a positive operator $ A $ on a Hilbert space $ \mathbb{H}, $ we define $ (\epsilon,A)- $approximate…

Functional Analysis · Mathematics 2024-08-14 Jeet Sen , Debmalya Sain , Kallol Paul

Weak almost contact manifolds, i.e., the linear complex structure on the contact distribution is replaced by a nonsingular skew-symmetric tensor, defined by the author and R. Wolak, allowed us to take a new look at the theory of contact…

Differential Geometry · Mathematics 2024-10-11 Vladimir Rovenski

We study almost symmetric numerical semigroups and semigroup rings. We describe a characteristic property of the minimal free resolution of the semigroup ring of an almost symmetric numerical semigroup. For almost symmetric semigroups…

Commutative Algebra · Mathematics 2018-07-03 Jürgen Herzog , Kei-ichi Watanabe

A symmetric tensor may be regarded as a partially symmetric tensor in several different ways. These produce different notions of rank for the symmetric tensor which are related by chains of inequalities. By exploiting algebraic tools such…

Algebraic Geometry · Mathematics 2019-12-03 Fulvio Gesmundo , Alessandro Oneto , Emanuele Ventura

One proves that each almost local-global semihereditary ring has the stacked basis property and is almost Bezout. If M is a finitely presented module, its torsion part tM is a direct sum of cyclic modules where the family of annhilators is…

Rings and Algebras · Mathematics 2007-10-03 Francois Couchot

Let S(D) be the surface produced by applying Seifert's algorithm to the oriented link diagram D. I prove that if D has no negative crossings then S(D) is a quasipositive Seifert surface, that is, S(D) embeds incompressibly on a fiber…

Geometric Topology · Mathematics 2007-05-23 Lee Rudolph

A lattice polytope translated by a rational vector is called an almost integral polytope. In this paper we investigate Ehrhart quasi-polynomials of almost integral polytopes. We study the relationship between the shape of the polytopes and…

Combinatorics · Mathematics 2023-08-31 Christopher de Vries , Masahiko Yoshinaga

We introduce the notions of pointwise almost h-slant submanifolds and pointwise almost h-semi-slant submanifolds as a generalization of slant submanifolds, pointwise slant submanifolds, semi-slant submanifolds, and pointwise semi-slant…

Differential Geometry · Mathematics 2016-01-14 Kwang-Soon Park

There is considered a connection with skew symmetric torsion on a quasi-K\"ahler manifold with Norden metric. Some necessary and sufficient conditions are derived for the corresponding curvature tensor to be K\"ahlerian. In the case when…

Differential Geometry · Mathematics 2009-07-14 Dimitar Mekerov

In this paper, we introduce a new class of nonnegative tensors --- strictly nonnegative tensors. A weakly irreducible nonnegative tensor is a strictly nonnegative tensor but not vice versa. We show that the spectral radius of a strictly…

Numerical Analysis · Mathematics 2015-03-13 Shenglong Hu , Zheng-Hai Huang , Liqun Qi

A new $Z$-eigenvalue inclusion theorem for tensors is given and proved to be tighter than those in [G. Wang, G.L. Zhou, L. Caccetta, $Z$-eigenvalue inclusion theorems for tensors, Discrete and Continuous Dynamical Systems Series B,22(1)…

Numerical Analysis · Mathematics 2017-05-16 Jianxing Zhao

We define and study a certain relative tensor product of subfactors over a modular tensor category. This gives a relative tensor product of two completely rational heterotic full local conformal nets with trivial superselection structures…

Operator Algebras · Mathematics 2017-12-01 Yasuyuki Kawahigashi

We develop the basic constructions of homological algebra in the (appropriately defined) unbounded derived categories of modules over algebras over coalgebras over noncommutative rings (which we call semialgebras over corings). We define…

Category Theory · Mathematics 2014-05-12 Leonid Positselski

We investigate which relations for families of commuting matrices are stable under small perturbations, or in other words, which commutative $C^*$-algebras $C(X)$ are matricially semiprojective. Extending the works of Davidson,…

Operator Algebras · Mathematics 2023-02-20 Dominic Enders , Tatiana Shulman