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Mathematics

arXiv preprints from January 1, 2026 through September 7, 2026 — 14:59:35 EST

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Posted in math.OC · 2026-01-12 · Luisa Estrada, Sasha Glendinning, Andrew Nugent

Speaking of Opinions: Comparing Approaches to Modelling Opinion Manipulation

This review outlines the major approaches to modelling opinion formation and manipulation in mathematics and computer science. Key tools such as ordinary and partial differential equations, stochastic models, control theory, and interaction protocols are introduced and compared as methods for describing manipulation. The review is...

💬 0 commentsarXiv:2601.07619v1PDF
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Posted in math.CO · 2026-01-12 · Byron Chin, Marcus Michelen

The random stable roommates problem typically has no solution

Assume that $n = 2k$ potential roommates each have an ordered preference of the $n-1$ others. A stable matching is a perfect matching of the $n$ roommates in which no two unmatched people prefer each other to their matched partners. In their seminal 1962 stable marriage paper, Gale and Shapley noted that not every instance of the...

💬 0 commentsarXiv:2601.07612v1PDF
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Posted in math.NA · 2026-01-12 · Jerome Droniou, Raman Kumar, Roland Masson, Ritesh Singla

A higher order polytopal method for contact mechanics with Tresca friction

In this work, we design and analyze a Discrete de Rham (DDR) scheme for a contact mechanics problem involving fractures along which a model of Tresca friction is considered. Our approach is based on a mixed formulation involving a displacement field and a Lagrange multiplier, enforcing the contact conditions, representing tractions at...

💬 0 commentsarXiv:2601.07586v2PDF
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Posted in math.OA · 2026-01-12 · Changyuan Gao, Julian Kranz

Exactness and Fell bundles with the approximation property over inverse semigroups

We prove that the reduced cross-sectional algebra of a Fell bundle with the approximation property over an inverse semigroup is exact if and only if the unit fiber of the Fell bundle is exact. This generalizes a recent result of the first-named author for actions of second countable locally compact Hausdorff groupoids on separable...

💬 0 commentsarXiv:2601.07572v2PDF
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Posted in math.LO · 2026-01-12 · Hiroyuki Ikari, Keita Yokoyama

Low-like basis theorems for Ramsey's theorem for pairs in first-order arithmetic

We construct an $\ll^2$-solution (also known as a weakly low solution) to ${\mathrm{D}^2}$ within ${\mathrm{B}Σ^0_{3}}$ and prove the $\ll^2$-basis theorem for $\mathrm{RT}^2$ over ${\mathrm{B}Σ^0_{3}}$. The $\ll^2$-basis theorem is a variant of the low basis theorem, which has recently received focus in the context of the first-order...

💬 0 commentsarXiv:2601.07569v1PDF
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Posted in math.FA · 2026-01-12 · Elisabetta Mangino, Alvaro Vargas-Moreno

Dynamics of the translation semigroup on directed metric trees

The dynamics of the left translation semigroup $\{T_t\}_{t \geq 0}$ on weighted $L^p$ spaces over a directed metric tree $L(G)$ is investigated. Necessary and sufficient conditions on the weight family $ρ$ for the strong continuity of the semigroup are provided. Furthermore, hypercyclicity and weak mixing properties are characterized...

💬 0 commentsarXiv:2601.07561v2PDF
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Posted in math.GT · 2026-01-12 · Bruno Martelli

An introduction to Coxeter polyhedra

This paper is an introduction to Coxeter polyhedra in spherical, Euclidean, and hyperbolic geometries. It consists of essentially two parts that could be read independently. In the first we introduce non-obtuse polyhedra in the spherical, Euclidean, and hyperbolic spaces, and prove various fundamental theorems originated from Andreev,...

💬 0 commentsarXiv:2601.07552v3PDF
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Posted in math.GR · 2026-01-12 · Ambrus Pál, Gereon Quick

$A_3$-formality for Demushkin groups at odd primes

We study a weak form of formality for differential graded algebras, called $A_3$-formality, for the cohomology of pro-p Demushkin groups at odd primes p. We show that the differential graded $\mathbb{F}_p$-algebras of continuous cochains of Demushkin groups with q-invariant not equal 3 are $A_3$-formal, whereas Demushkin groups with...

💬 0 commentsarXiv:2601.07551v2PDF
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Posted in math.CO · 2026-01-12 · Sicheng Lu, Yi Song

Enumeration of weighted plane trees by a permutation model

This work addresses an enumeration problem on weighted bi-colored plane trees with prescribed vertex data, with all vertices labeled distinctly. We give a bijection proof of the enumeration formula originally due to Kochetkov, hence affirmatively answer a question of Adrianov-Pakovich-Zvonkin. The argument is purely combinatorial and...

💬 0 commentsarXiv:2601.07544v1PDF
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Posted in math.GR · 2026-01-12 · Raphael Appenzeller

Semisimple algebraic groups over real closed fields

We give a self-contained introduction to linear algebraic and semialgebraic groups over real closed fields, and we generalize several key results about semisimple Lie groups to algebraic and semialgebraic groups over real closed fields. We prove that a torus in a semisimple algebraic group is maximal $\mathbb{R}$-split if and only if...

💬 0 commentsarXiv:2601.07732v1PDF
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Posted in math.NA · 2026-01-12 · Jithin D. George, Julian Koellermeier, Samuel Y. Jung, Niall M. Mangan

Explicit complex time integrators for stiff problems

Most numerical methods for time integration use real-valued time steps. Complex time steps, however, can provide an additional degree of freedom, as we can select the magnitude of the time step in both the real and imaginary directions. We show that specific paths in the complex time plane lead to expanded stability regions, providing...

💬 0 commentsarXiv:2601.07730v1PDF
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Posted in math.SG · 2026-01-12 · Igor Uljarević

A Note on Somewhere Positive Loops of Contactomorphisms

In this note, we consider contractible loops of contactomorphisms that are positive over some non-empty closed subset of a contact manifold. Such closed subsets are called immaterial. We argue that the complement of a Reeb-invariant immaterial subset can be seen as big in contact geometric terms. This is supported by two results: one...

💬 0 commentsarXiv:2601.07714v2PDF
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Posted in math.NT · 2026-01-12 · Debargha Banerjee, Srijan Das

A note on extensions of $p$-adic representations of $\mathrm{GL}_2(\mathbb{Q}_p)$

We compute extension groups in the category of duals of $p$-adic Banach space representations of $\mathrm{GL}_2(\mathbb{Q}_p)$. Focusing on representations arising from the $p$-adic local Langlands correspondence for generic Galois representations, we classify these extensions completely. These results are then applied to prove the...

💬 0 commentsarXiv:2601.07707v2PDF
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Posted in math.GT · 2026-01-12 · Mason Hart

Topology of domains of discontinuity for Anosov representations via circle actions

Among the remarkable properties shared with convex cocompact representations, Anosov representations admit cocompact domains of discontinuity in flag varieties. For representations produced by embedding Fuchsian representations into higher rank Lie groups, these domains are known to admit fiber bundle structures and the structure...

💬 0 commentsarXiv:2601.07705v1PDF
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Posted in math.NA · 2026-01-12 · Armando Maria Monforte

TMATDG: applying TDG methods to multiple scattering via T-matrix approximation

We present a MATLAB package for the solution of multiple scattering problems, coupling Trefftz Discontinuos Galerkin methods for Helmholtz scattering with the T-matrix method. We rely on the TMATROM package to numerically approximate the T-matrices and deal with multiple scattering problem, providing a framework to handle scattering...

💬 0 commentsarXiv:2601.07704v2PDF
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Posted in math.MG · 2026-01-12 · Georg Grützner

Asymptotic-Möbius maps

We introduce asymptotic-Möbius (AM) maps, a large-scale analogue of quasi-Möbius maps tailored to geometric group theory. AM-maps capture coarse cross-ratio behavior for configurations of points that lie far apart, providing a notion of "conformality at infinity" that is stable under quasi-isometries, compatible with scaling limits,...

💬 0 commentsarXiv:2601.07702v1PDF
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Posted in math.CV · 2026-01-12 · Sayani Bera, Kaushal Verma

Rigidity of the escaping set of polynomial automorphisms of $\mathbb{C}^2$

Let $H$ be a polynomial automorphism of $\mathbb{C}^2$ of positive entropy and degree $d \ge 2$. We prove that the escaping set $U^+$ (or equivalently, the non-escaping set $K^+$), of $H$ is rigid under the action of holomorphic automorphisms of $\mathbb{C}^2$. Specifically, every holomorphic automorphism of $\mathbb{C}^2$ that...

💬 0 commentsarXiv:2601.07681v2PDF
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Posted in math.CO · 2026-01-12 · Yandong Bai, Haoyun Gu

Cross-intersecting families with covering number constraints

Two families $\mathcal{F}$ and $\mathcal{G}$ are cross-intersecting if every set in $\mathcal{F}$ intersects every set in $\mathcal{G}$. The covering number $τ(\mathcal{F})$ of a family $\mathcal{F}$ is the minimum size of a set that intersects every member of $\mathcal{F}$. In 1992, Frankl and Tokushige determined the maximum of...

💬 0 commentsarXiv:2601.07679v1PDF
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Posted in math.DG · 2026-01-12 · Xi Sisi Shen, Kevin Smith

Coupled continuity equations for constant scalar curvature Kähler metrics

Inspired by a parabolic system of Li-Yuan-Zhang and the continuity equation of La Nave-Tian, we study a system of elliptic equations for a Kähler metric $ω$ and a closed $(1, 1)$-form $α$. Assuming a uniform estimate for $ω$, we prove higher order estimates and smooth convergence to a cscK metric coupled to a harmonic $(1, 1)$-form. A...

💬 0 commentsarXiv:2601.07677v1PDF
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Posted in math.MG · 2026-01-12 · Kaie Kubjas, Lilja Metsälampi

Geometry of low nonnegative rank matrix completion

We study completion of partial matrices with nonnegative entries to matrices of nonnegative rank at most $r$ for some $r \in \mathbb{N}$. Most of our results are for $r \leq 3$. We show that a partial matrix with nonnegative entries has a nonnegative rank-1 completion if and only if it has a rank-1 completion. This is not true in...

💬 0 commentsarXiv:2601.07658v1PDF
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Posted in math.OC · 2026-01-12 · Lea Enzi, Stefan Thonhauser

To report or not to report: Optimal claim reporting in a bonus-malus system

We study an optimal claim reporting problem in a bonus-malus setting. We assume, that the insurance contract consists of two regimes, where reporting a claim leads to a transition to a higher-premium regime, whereas remaining claim-free for a prespecified time period results in a shift to the lower premium regime. The insured can...

💬 0 commentsarXiv:2601.07655v1PDF