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🔍 ryan gallagher 📂 Mathematics
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Mathematics Preprint PDF DOI

Deformations of fibered Calabi--Yau varieties

Benjamin Bakker, Kristin DeVleming, Stefano Filipazzi, Radu Laza, Jennifer Li, Roberto Svaldi, Chengxi Wang, Junyan Zhao · 2026

Koll\'{a}r showed that small deformations of elliptically fibered smooth $K$-torsion varieties with $H^2(X,\mathcal{O}_X)=0$ remain elliptically fibered. We extend this result to any fibered smooth $K…

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Mathematics Preprint PDF DOI

On the pointwise convergence of NLS flow on $ \S^2 $

Fanfei Meng, Yilin Song, Chenmin Sun, Ruixiao Zhang, Jiqiang Zheng · 2026

In this paper, we study the almost everywhere convergence of the cubic nonlinear Schr\"odinger flow to the initial data on $\mathbb S^2$, \begin{equation*} iu_t + \Delta_g u = |u|^2u, \quad (t,x)\…

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Mathematics Preprint PDF DOI

The discrete quantum group $su_q(2)$ and its dual

Alfons Van Daele · 2026

Discrete quantum groups were introduced as duals of compact quantum groups by Podle\'s and Woronowicz in 1990. They have been studied intrinsically by Effros and Ruan (1994) and by the author (1996). …

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Mathematics Preprint PDF DOI

The motivic tt-geometry of real quadrics

Jean Paul Schemeil · 2026

We study the tensor-triangular geometry of the category of Voevodsky motives generated by real quadrics. At the prime 2, we determine its Balmer spectrum, and find that it is a countably infinite, non…

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Mathematics Preprint PDF DOI

Complex cells in sharply o-minimal structures

Gal Binyamini, Oded Carmon, Dmitry Novikov · 2026

We extend the theory of complex cells introduced by Binyamini and Novikov to the sharply o-minimal setting, obtaining cellular preparation and parameterization theorems which are polynomially effectiv…

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Mathematics Preprint PDF DOI

Four Limit Cycles in Three-Dimensional Competitive Lotka-Volterra Systems of Class 28 in Zeeman's Classification

Mingzhi Hu, Zhengyi Lu, Yong Luo · 2026

In this paper, a three-dimensional competitive Lotka-Volterra system with four limit cycles is constructed for class 28 in Zeeman's classification. Combined with existing results -- from Gyllenberg an…

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Mathematics Preprint PDF DOI

Sieving with square conditions and applications to Hilbert cubes in arithmetic sets

Rainer Dietmann, Christian Elsholtz, Imre Ruzsa · 2026

The purpose of this paper is twofold: 1) Applications of Gallagher's larger sieve modulo prime squares do not work. In some relevant cases we can transform the residue class information modulo $p^2$ t…

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Mathematics Preprint PDF DOI

Enumerative geometry of $K3$ surfaces

Thomas Dedieu · 2026

The aim of these notes is to explain various enumerative results about $K3$ surfaces without assuming familiarity with Gromov--Witten theory. The enumerative results in question are due to Beauville, …

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Mathematics Preprint PDF DOI

The largest 5th pivot may be the root of a 61st degree polynomial

James Chen, Alan Edelman, John Urschel · 2026

This paper introduces a number of new techniques in the study of the famous question from numerical linear algebra: what is the largest possible growth factor when performing Gaussian elimination with…

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Mathematics Preprint PDF DOI

On automorphism group of the reduced finitary power monoid of the additive group of integers

Dein Wong, Songnian Xu, Chi Zhang, Zhijun Wang · 2026

Let $\mathbb{Z}$ be the additive group of all integers and $\mathbb{N}$ the sub-monoid of $\mathbb{Z}$ of all non-negative integers. For a finite subset $X$ of $\mathbb{Z}$, we denote by ${\rm max}\ X…

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Mathematics Preprint PDF DOI

Construction of a Closed Hyperbolic Surface of Arbitrarily Small Eigenvalue of Prescribed Serial Number

Susovan Pal · 2026

In this paper we construct, for given any small positive number $\epsilon$ and given natural number $n$, and given any closed hyperbolic surface $M$, a closed hyperbolic covering surface $\widetilde{M…

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Mathematics Preprint PDF DOI

Spectral Theory of Fractional Cooperative Systems and Threshold Dynamics in Epidemic Models

Cong-Bang Trang, Hoang-Hung Vo · 2026

Spectral analysis has long been recognized as a fundamental tool for studying the existence, uniqueness, and qualitative behavior of solutions to semilinear elliptic and parabolic equations, as well a…

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Mathematics Preprint PDF DOI

Subvarieties of complete intersections of large degree

Francesco Bastianelli, Gianluca Pacienza · 2026

We study subvarieties of very general complete intersections $X\subset \mathbb{P}^n$ of multidegree $(d_1,\dots,d_c)$, when $d:= d_1+\dots +d_c$ is sufficiently large. In a seminal paper Ein proved th…

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Mathematics Preprint PDF DOI

The Cauchy problem for the generalized KdV equation in the Sobolev space $H^{s}(\mathbf{R})$

Xiangqian Yan, Yongsheng Li, Juan Huang, Jianhua Huang, Wei Yan · 2026

In this paper, we are concerned with the Cauchy problem for the generalized KdV equation with random data and rough data. Firstly, when $s\in\mathbf{R}$, by using the initial value randomization techn…

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Mathematics Preprint PDF DOI

Simple connectedness of the Ran space

Janis Lazovskis · 2026

The space of all finite non-empty subsets of a topological space $X$, also known as the Ran space of $X$, is weakly contractible for $X$ path connected. We consider subspaces $\mathrm{Ran}_{\leqslant …

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Mathematics Preprint PDF DOI

Cohomological rigidity of solvable Lie algebras of maximal ran

B.A. Omirov, G.O. Solijanova, G.Kh. Urazmatov · 2026

We study the second cohomology group with coefficients in the adjoint module for a class of solvable Lie algebras $\mathcal{R}_{\mathcal{T}}$ that arise as maximal solvable extensions of nilpotent Lie…

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Mathematics Preprint PDF DOI

Spaltenstein Varieties Associated with Pseudo-Polarizations

Xueqing Wen, Yaoxiong Wen · 2026

We introduce minimal Richardson orbits and pseudo-polarizations for nilpotent orbits in classical Lie algebras of types B, C, and D. For any nilpotent orbit, we classify all minimal Richardson orbits …

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Mathematics Preprint PDF DOI

Principal Distribution Isomorphisms and Almost Hermitian geometry on Isoparametric Hypersurfaces

Lixin Xiao, Wenjiao Yan, Wenjin Zhang · 2026

This paper investigates the isomorphisms between principal distributions $\mathcal{D}_k$ $(k=1,\dots 4)$ on OT--FKM type isoparametric hypersurfaces in spheres. We recover the isomorphism $\mathcal{D}…

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Mathematics Preprint PDF DOI

The isomorphism problem for reduced finitary power monoids

Balint Rago · 2026

Let $H$ be a multiplicatively written monoid with identity $1_H$ and let $\mathcal{P}_{\text{fin},1}(H)$ denote the reduced finitary power monoid of $H$, that is, the monoid consisting of all finite s…

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Mathematics Preprint PDF DOI

Divergence Identity for the scalar curvature and Rigidity of Codazzi Tensors

Xu Cheng, Andres Lipa, Detang Zhou · 2026

We introduce a local vector field on an $n$-dimensional Riemannian manifold, defined as the sum of the covariant derivatives of a local orthonormal frame, and derive an explicit identity for its diver…

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