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107 works

math.NT — Number Theory

Stark units for real quadratic fields and reciprocity laws

Contributed by Danylo Radchenko, Campbell Wheeler

We prove that every value of the arithmetic finite quantum dilogarithms constructed by Radchenko and Wheeler (arXiv:2609.21892) is an algebraic unit, and determine the Artin action for arbitrary quadratic pseudolattices. In particular, the associated Stark units belong to the predicted ray class fields and have the predicted Galois action. We use finite Fourier transforms and distribution relations to obtain Frobenius congruences. We also give conductor bounds for individual values and obtain the unitary conjugates needed for Zauner's conjecture.

A mix of human-written and AI-generated textHuman understanding: all partsArtin reciprocityFrobenius congruencesReal quadratic fieldsStark unitsfinite quantum dilogarithmsray class fields

Oct 10, 2026PDF ↗View work →

hexagon:2610.00175v1

math.QA — Quantum Algebra

The Haagerup VOA at Central Charge Eight

Contributed by Andrew Riesen

We give an explicit construction of a vertex operator algebra $U$ of central charge eight inside $V_{E_6\oplus A_2}$ , and prove the ribbon equivalence $\Rep(U)\simeq Z(\HH_3)$, where $\HH_3$ is a Haagerup fusion category. The algebra is generated as a vertex algebra by six affine generators and three specified weight-two vectors. The argument combines exact lattice-vector calculations with an all-weight strong-generation induction, a finite presentation and semisimple descent for a full corner of Zhu's algebra, and the actual multiplication of two holomorphic $E_8$ extensions. The categorical identification uses splitting maps and a comparison with the Evans--Gannon reconstruction, not modular data alone.

A mix of human-written and AI-generated textHuman understanding: some parts

Oct 10, 2026PDF ↗View work →

hexagon:2610.00182v1

math.RT — Representation Theory

A counterexample to Han’s conjecture over arbitrary fields

Contributed by 琪越唐

Based on the constructions of Kong–Liu–Shen and Liu–Shen, we give a counterexample to Han’s conjecture over every field.

Primarily AI-generated textHuman understanding: no partsHan’s conjecture

Oct 10, 2026PDF ↗View work →

hexagon:2610.00180v1

math.OA — Operator Algebras

A variational formula for affine semicircular determinants

Contributed by Sheng Yin

We express the Fuglede--Kadison determinant of an affine pencil in free semicircular operators as an infimum over positive definite matrices. The infimum is attained if and only if the pencil is boundedly invertible, in which case its minimizer is unique. At zero constant term, a scalar rescaling recovers the determinant-capacity identity of Mai and Speicher. For selfadjoint coefficients we compare the formula with a strictly constrained Hilbert--Schmidt variational principle and establish ordered min--max formulas under their respective positivity hypotheses. Strictly positive pencils admit a minimum over a linear matrix inequality. Applications to Brown measure include a uniform determinant lower bound, restrictions on atoms, radial distribution formulas, and a Hessian formula for the regularized density. The text of this manuscript was generated entirely by OpenAI's large language model Astra.

Primarily AI-generated textHuman understanding: no partsFree probabilityFuglede–Kadison determinantOperator-valued semicircular elements

Oct 10, 2026PDF ↗View work →

hexagon:2610.00185v1

math.CA — Classical Analysis and ODEs

Arithmetic progressions with prescribed lp gaps

Contributed by Vjekoslav Kovač

For every $n\ge3$ and $p\in[1,\infty)\setminus\{1,2,\ldots,n-1\}$ , we prove that every measurable subset of $\mathbf{R}^d$ of positive upper Banach density, with $d\ge2^{n-2}+1$ , contains an $n$ -term arithmetic progression with every sufficiently large prescribed $\ell^p$ gap.

Primarily AI-generated textHuman understanding: some partsEuclidean Ramsey theorydensity theoremmultilinear estimateoscillatory integralsingular integral

Oct 10, 2026PDF ↗View work →

hexagon:2610.00176v1

math.CA — Classical Analysis and ODEs

Superexponentially decaying sequences in the Erdos similarity problem

Contributed by Vjekoslav Kovač

We prove a non-universality criterion for the Erd\H{o}s similarity conjecture that applies beyond exponential (i.e., geometric) decay. In particular, it covers decreasing positive null sequences satisfying $\log(1/a_n)=o(n\log\log n)$ and $\log(a_n/a_{n+1})\ge e^{-n^\alpha}$ eventually for some $0<\alpha<1$ .

Primarily AI-generated textHuman understanding: some partsLebesgue measureconfigurationmeasure theory

Oct 10, 2026PDF ↗View work →

hexagon:2610.00179v1

math.RT — Representation Theory

Representation embeddings and the third Brauer--Thrall conjecture

Contributed by Haruhisa Enomoto

We show that every representation-infinite finite-dimensional algebra over an algebraically closed field has an indecomposable module of each infinite dimension. This settles, over algebraically closed fields, Simson's conjecture, also called the third Brauer--Thrall conjecture, that such an algebra has indecomposable modules of arbitrarily large cardinality. To construct these modules, we extend a representation embedding of Bongartz from finite-dimensional Kronecker modules without a simple injective summand to a representation embedding of such Kronecker modules of arbitrary dimension, which commutes with direct sums and filtered colimits and preserves the dimension of infinite-dimensional modules. Applying it to the indecomposable Kronecker modules of every infinite dimension constructed by G\"obel and Simson gives the required modules.

Primarily AI-generated textHuman understanding: some partsBrauer--Thrall conjectureGalois coveringKronecker modulelarge indecomposable modulerepresentation embedding

Oct 10, 2026PDF ↗View work →

hexagon:2610.00165v1

math.MG — Metric Geometry

Multi-coverings by lattice translates of convex bodies

Contributed by Scott Kominers

We show that for every convex body $K\subset\mathbb R^n$ ( $n\ge2$ ), every $0<\varepsilon<1$ , and every prescribed density $\rho\ge A_\varepsilon n\log n$ , there is an arrangement of translates of $K$ along a single lattice with mean multiplicity exactly $\rho$ and multiplicity at least $(1-\varepsilon)\rho$ everywhere. Consequently, lattice $k$ -fold coverings exist with density at most $\max\{(1+\varepsilon)k,C_\varepsilon n\log n\}$ , where $C_\varepsilon$ depends only on $\varepsilon$ . In sufficiently large dimension $n$ , a version with prescribed common covolume holds simultaneously for up to $\exp(n^{c_0})$ bodies whose uniform distributions have a common covariance matrix, with $c_0>0$ absolute. The proof builds on OpenAI's horizontal–vertical construction for single-lattice coverings and uses Gaussian layer averaging and Laplace bounds for covering counts.

A mix of human-written and AI-generated textHuman understanding: all partsGeometry of numbersconvex bodiesconvex geometrycovering densitycovering multiplicitylattice coveringmulti-covering

Oct 09, 2026PDF ↗View work →

hexagon:2610.00161v1

math.NT — Number Theory

THE CROSS-ENERGY OF DIRICHLET PARTIAL SUMS AND THE ZEROS OF THE RIEMANN ZETA FUNCTION

Contributed by Pedro Caceres

Let X_n(s) = Σ_{k≤n} k⁻ˢ and let C₂(n,s) = |X_n(s)|² − |X_{n−1}(s)|² − n⁻²σ be the cross-energy of consecutive partial sums. At every point of the critical strip the limit of C₂(n,s) is 1/(¼ + t²), 0 or +∞ according as σ = ½, σ > ½ or σ < ½; this trichotomy is the trace of the pole at s = 1. On the critical line the associated helix has a natural orientation whose signed radius is Hardy’s Z(t), and the zeros of the truncated functions spiral into the zeros of ζ at the rate n⁻ᵝ. We prove that the mean energy of the normalized error E(u) in the prime number theorem equals Σ_ρ lim_{n→∞} C₂(n,ρ) in [0,∞]; it is at least 2 + γ₀ − log(4π), with equality if and only if the Riemann hypothesis (RH) holds and all zeros are simple, and an unconditional local version expresses the energy in a Gaussian window as a double sum over zeros. We then study the pointwise inequality S(σ,t) = ∂σ log|ξ(σ + it)| > 0, which is equivalent to RH: an off-line pair lowers S exactly inside a disc, the failure set at abscissa σ up to height T has measure at most N(σ,T + 1), and S is Weil’s functional at a Poisson kernel, whose truncation is an exact finite expression in the primes up to eᴸ. Every criterion is tested against the Davenport–Heilbronn function, which has zeros off the critical line, and against its Euler-product twin L(s,χ) mod 5: the former violates each criterion in the predicted way, the latter behaves like ζ. For ζ, the primes up to 10⁸ give mean energy 0.0453 against 0.0462. On the circle of the Euler factor of a prime p the zeros lean toward the angle π, and toward π + argχ(p) for L(s,χ). We do not prove the Riemann hypothesis.

A mix of human-written and AI-generated textHuman understanding: all partsC2 FunctionDirichlet SumsRiemann Zeta Function

Oct 09, 2026PDF ↗View work →

hexagon:2610.00169v1

math.PR — Probability

Classical infinite divisibility, self-decomposability and bell-shape of free stable laws

Contributed by Min WANG

We determine the classical infinite divisibility, self-decomposability and extended Thorin regions of the strictly free stable family. Above index one, infinite divisibility and self-decomposability hold on two extremal skewness intervals, with distinct maximal indices $\alpha_{\mathrm{ID}}=1.5240739610\ldots$ and $\alpha_{\mathrm{SD}}=1.4283571142\ldots$ . Below one, every law is self-decomposable, whereas the Thorin region is a central interval; the optimal uniform bound is $4/5$ . We characterize the boundaries by global contact conditions and derive their different asymptotic scales at index one. A common phase representation also gives an exact bell-shape test, strictly bell-shaped examples outside the Thorin class, and an unbounded number of skewness components near one. The exceptional free one-stable family admits an explicit integer criterion. The proofs combine analytic estimates with finite interval certificates. The bell-shape results do not constitute a full parameter classification.

Primarily AI-generated textHuman understanding: no parts

Oct 09, 2026PDF ↗View work →

hexagon:2610.00173v1

math.MP — Mathematical Physics

Wave Mechanics

Contributed by Rajesh Dachiraju

We introduce a complex Hilbert space structure on $L^2(\mathbb{T}^m;\mathbb{C})$ in which the Hilbert transform on the torus is incorporated directly into the metric and inner product. The resulting geometry is defined via a bounded linear embedding that couples each function to its Hilbert transform, yielding an inner product with both symmetric and symplectic components. Within this framework, we redefine weak differentiation intrinsically using the complex Hilbert-space inner product rather than the ambient $L^2$ pairing. We show that this intrinsic weak derivative coincides with the classical weak derivative on its natural domain, while remaining geometrically well defined on the full space. The derivative operator is shown to be densely defined and skew-adjoint, with a purely imaginary, discrete spectrum. Its eigenfunctions are given by the Fourier modes on the torus, which induce a complete orthonormal basis adapted to the Hilbert-transform metric. This construction yields a spectral representation in which differentiation is diagonal and the Hilbert transform is absorbed into the notion of differentiability itself, providing a unified analytic and geometric framework. We formulate wave mechanics intrinsically in this complex Hilbert space, define wave function, scalar and vector potentials and associated energy functional, derive space time wave equation, derive its solution, prove existence and uniqueness and establish regularity of the solution.

A mix of human-written and AI-generated textHuman understanding: all parts

Oct 09, 2026PDF ↗View work →

hexagon:2610.00167v1

math.GR — Group Theory

The Sharp Commutator Bound for the Polymath14 Inequality

Contributed by Jaeyeon Shim

We present a simplified proof of the Polymath14 inequality, along with a new sharpness result.

Primarily human-written textHuman understanding: all partsfunctional equation

Oct 09, 2026PDF ↗View work →

hexagon:2610.00170v1

math.CO — Combinatorics

The number of multiplicity sets of n-point plane line collections grows as exp(Theta(sqrt(n)))

Contributed by Raphael DUCAY

For a set P of n points in the plane R^2, let A(P) be the set of multiplicities of P, i.e. the sizes |ell cap P| >= 2 of the subsets of P lying on a common line ell, and let F(n) be the number of distinct multiplicity sets A(P) as P ranges over all n-point sets. Erdos problem 607 (erdosproblems.com/607) asks whether F(n) <= exp(O(sqrt n)), remarking that the sqrt(n) scale is easy to see to be best possible. We prove the upper bound F(n) <= exp(c sqrt n) for an absolute constant c > 0. The proof is a three-step reduction to a published result of Colbourn-Phelps-Rodl, "Block sizes in pairwise balanced designs" (Canad. Math. Bull. 27(3), 375-380, 1984): (1) the lines determined by P, restricted to P, form a pairwise balanced design (PBD) of order n - every unordered pair of points lies in exactly one such block; (2) the profile set of block sizes of this PBD is exactly A(P); (3) Theorem 2.4 of Colbourn-Phelps-Rodl bounds the number g(n) of profile sets of order-n PBDs by exp(c2 sqrt n), hence F(n) <= g(n) < exp(c2 sqrt n). Combined with the grid construction of Szemeredi-Trotter (1983) this settles the order of magnitude exactly: F(n) = exp(Theta(sqrt n)). The essential observation is that plane line collections are precisely PBDs, so the published design-theoretic bound applies to multiplicity sets directly. A Lean 4 machine-checked formalization of the reduction is in progress for the Palomar registry and will be linked from this deposit upon acceptance.

A mix of human-written and AI-generated textHuman understanding: all partscombinatorial-geometryerdos-problem-607line-geometriesmultiplicity-setspairwise-balanced-designs

Oct 09, 2026PDF ↗View work →

hexagon:2610.00171v1

math.CO — Combinatorics

Measurable Independence Density Equals the Finite Independence-Ratio Infimum in the Euclidean Plane

Contributed by Ákos Dúcz

Let m1(R^2) be the supremum of upper densities of Lebesgue-measurable subsets of the plane containing no pair of points at distance one. We show, using the spectral rigidity theorem in OpenAI's recent proof that the plane is not five-colorable, that m1(R^2) = inf_G alpha(G)/|V(G)|, where G ranges over nonempty finite unit-distance graphs in the plane. The argument constructs an isometry-invariant law on independent subsets of the countable algebraic plane, projects the occupancy indicator onto the continuous spectral factor without changing its expectation, and extracts a measurable independent set with arbitrarily small density loss. As a consequence, if f(n) is the least independence number among unit-distance graphs on n vertices, then f(n)/n converges to m1(R^2). The proof is nonquantitative and uses the cited spectral rigidity result as a black box.

Primarily AI-generated textHuman understanding: some partsSpectral RigidityUnit-distance graphsindependence ratioinvariant random independent setsmeasurable sets

Oct 09, 2026PDF ↗View work →

hexagon:2610.00172v1

cs.DS — Data Structures and Algorithms

From Snapshots to Processes: Dynamic Contact Algebras as a Foundation for Process-Oriented GIS

Contributed by John Hessler

Geographic information science has argued for three decades that representing change requires moving from time-stamped snapshots to events and processes. This ontological shift has not been matched by a formal foundation with the properties a GIS needs: explicit axioms, representation theorems, and decidable reasoning. We propose dynamic mereotopology, in the form of Vakarelov’s dynamic contact algebras (DCAs), as a candidate foundation. DCAs are point-free with respect to both space and time. Regions are histories, primitive relations include space contact, time contact and precedence, moments are recovered as clusters of the time-contact relation, and properties of time correspond to axioms about regions alone. Using Grenon and Smith’s distinction between SNAP (snapshot) and SPAN (process) ontologies, we argue that DCAs originate on the SNAP side, since they are abstracted from a snapshot model, yet their primitives already carry much of what a SPAN ontology requires. We then identify precisely what is still missing for a process-oriented GIS: process and participation primitives, continuity of change, freedom from global simultaneity, identity under splitting and merging, and granularity. We develop a SPAN-first extension. For two of its components we give full proofs: a point-free continuity axiom, shown to express exactly the intended condition in discrete time and in finitely variable dense time, and a set of correspondences showing which axioms of continuous space hold at every finite resolution of discrete data and which emerge only in the limit of refinement. The remaining proposals are stated as conjectures, and the framework is tested against three case studies: a flood, a wildfire, and a pandemic.

A mix of human-written and AI-generated textHuman understanding: all partsdynamic mereotopology; contact algebra; boolean algebra

Oct 09, 2026PDF ↗View work →

hexagon:2610.00162v1

math.ST — Statistics Theory

Nearly Minimax Variance Estimation Under Rough Random Design

Contributed by P. M. Aronow, Patrick Lopatto

We determine, up to a power of $\log n$ , the minimax risk for constant conditional variance estimation under rough random design. The unknown design density is bounded above and away from zero, with no smoothness assumption, and the conditional error laws may depend on the covariates and have uniformly bounded fourth moments. For an $s$ -Hölder regression function with $s>1$ in dimension $d>4s$ , the minimax root-mean-square risk lies, for all sufficiently large $n$ , between $c\Psi_n$ and $C\Psi_n(\log n)^{\Gamma}$ , where $\Psi_n=n^{-2(s+1)/(d+4)}e^{-\kappa\sqrt{\log n}}(\log n)^{(s-1)/(d+4)}$ and the constants $\kappa>0$ and $\Gamma>0$ are explicit. In particular, the minimax exponent is $2(s+1)/(d+4)$ , the minimax risk is smaller than $n^{-2(s+1)/(d+4)}$ by a stretched-exponential factor whose constant $\kappa$ is identified, and the rate proposed by Robins is not uniformly attainable over this model class. For $0<s\le1$ , we show that the exact minimax rate is $n^{-1/2}\vee n^{-4s/(d+4s)}$ ; for $s>1$ and $d\le4s$ , it is $n^{-1/2}$ .

Primarily AI-generated textHuman understanding: some parts

Oct 08, 2026PDF ↗View work →

hexagon:2610.00163v1

math.MG — Metric Geometry

An exponential improvement for Borsuk's problem

Contributed by Andriy Prymak

We present a method for improving the classical exponential base $\sqrt{3/2}$ in the upper bound for Borsuk's partition number. The emphasis is on explaining the method rather than optimizing the bound. The problem is reduced to constructing directions which make an acute angle with every member of a prescribed spherical set. These play the same role as the illuminating directions in Schramm's method. The geometric ingredients are an antipodal pairing, a lift by one coordinate, and reflection in a self-dual cone. This reflection folds Euclidean space into the cone. A translation opposite to the horizontal part of its Gaussian mean makes the required supporting inequalities hold with high probability. The Gaussian Poincar\'e inequality controls the mean, and the formula for translating a Gaussian density bounds the measure cost of this construction.

Primarily AI-generated textHuman understanding: all partsBorsuk's partition problemGaussian Poincare inequalityGaussian measureasymptotic convex geometryself-dual conesspherical polarity

Oct 08, 2026PDF ↗View work →

hexagon:2610.00160v1

stat.TH — Statistics Theory

Binary Regression for BV Class Conditional Probability

Contributed by Rajesh Dachiraju

In this article we solve the problem of binary regression when the class conditional probability is a multivariate function of bounded variation. We study the consistency of binary regression under a nonparametric sampling framework. Sufficient conditions are established for the convergence of the binary regression estimator, and quantitative error estimates are obtained. We further strengthen the analysis by introducing the assumption that the feature vectors possess a point density measure of bounded variation. Under this geometric regularity assumption, the expectation-based error estimate is replaced by a deterministic estimate, yielding deterministic convergence in the $L^{2}$ norm and, consequently, almost sure convergence. The analysis demonstrates that the geometric distribution of the sampling points plays a fundamental role in the approximation properties of the estimator. Although the analysis is carried out on the torus $\mathbb{T}^{m}$ , the results extend to arbitrary bounded Lipschitz domains after affine scaling, embedding into $\mathbb{T}^{m}$ , and zero extension. The point density measure framework provides a deterministic geometric perspective on binary regression and establishes a connection between sampling geometry, bounded variation, and convergence theory.

A mix of human-written and AI-generated textHuman understanding: some parts

Oct 08, 2026PDF ↗View work →

hexagon:2610.00159v1

math.GT — Geometric Topology

The torus with asymptotically the fewest simple closed geodesics

Contributed by Phuc Thinh Dang, Trong Toan Dao, Nhat Minh Doan

We prove that the modular torus uniquely minimizes the area of the stable-norm unit ball among complete finite-area hyperbolic once-punctured tori, resolving the McShane--Rivin area conjecture. It therefore has fewer simple closed geodesics of length at most $L$ than any fixed nonmodular torus for all sufficiently large $L$ . We also bound the area increase away from the modular torus and determine its leading growth and first correction term as the systole tends to zero, with error bounds independent of the twist.

Primarily human-written textHuman understanding: all partsFarey polygonsHyperbolic surfacesMcShane–Rivin area conjectureMirzakhani functions.modular torussimple closed geodesicsstable norm

Oct 08, 2026PDF ↗View work →

hexagon:2610.00157v1

math.ST — Statistics Theory

Nearly Minimax Rates for Functional Estimation Under Rough Random Design

Contributed by P. M. Aronow, Nathan Kallus, Patrick Lopatto

We establish nearly minimax bounds for missing-at-random means, treatment effects, and expected conditional covariances under rough random design. For two nuisance functions with average H\"older smoothness $s$ in dimension $d$ , the minimax root-mean-square error is $n^{-2s/d+o(1)}$ when $s<d/4$ and of order $n^{-1/2}$ when $s\ge d/4$ . The first rate confirms the rough-design exponent suggested by higher-order influence function theory. In the generic model with an unknown bounded density weight, our upper and lower bounds differ by only polylogarithmic factors and identify a leading correction $e^{-\kappa\sqrt{\log n}}$ when $s<d/4$ , with $\kappa$ explicit in terms of $s/d$ and the weight bounds. For the expected conditional covariance, the same exponent and the same constant $\kappa$ were obtained independently and concurrently by S. Park (arXiv:2610.05006). For models with separately bounded density and propensity, we identify the same polynomial exponent and the explicit leading correction, with an $o(\sqrt{\log n})$ remainder in the logarithm of the risk.

Primarily AI-generated textHuman understanding: some parts

Oct 08, 2026PDF ↗View work →

hexagon:2610.00155v1

math.PR — Probability

The Parisi Formula for the Edwards–Anderson Model in the High-Dimensional Limit

Contributed by P. M. Aronow, Patrick Lopatto

We study the Edwards–Anderson spin glass on the torus $(\mathbb{Z}/L\mathbb{Z})^d$ , with independent Gaussian couplings of variance $1/(2d)$ between nearest neighbors. We prove that, as $d\to\infty$ , its free energy converges to that of the Sherrington–Kirkpatrick model, given by the Parisi formula, at every temperature and in every uniform external field, uniformly in the side length $L$ . The same holds on the hypercube $\{0,1\}^d$ , and the ground-state energies converge to the Sherrington–Kirkpatrick ground-state energy.

Primarily AI-generated textHuman understanding: some partsparisi formulaspin glass

Oct 08, 2026PDF ↗View work →

hexagon:2610.00156v1

math.NT — Number Theory

Modularity of elliptic curves over totally real field and CM fields not containing \zeta_5

Contributed by Bao Le Hung

This notes tries to parse the basic structure of OpenAI's new argument proving modularity of elliptic curves over imaginary quadratic fields. The argument also proves modularity over all totally real field, and in the original form, modularity over CM fields not containing \zeta_5. The general CM case has also now been resolved by an independent repository which improves the Caraiani-Newton modularity lifting theorem for CM field at the prime 5, which was the main reason for the extra hypothesis. I kept the argument in the totally real case separate to highlight the main new idea in the OpenAI proof, which is orthogonal to modularity lifting theorems.

A mix of human-written and AI-generated textHuman understanding: some partsModularity

Oct 08, 2026PDF ↗View work →

hexagon:2610.00154v1

math.PR — Probability

Parisi formula for Ising and Spherical Perceptrons

Contributed by Daniel Fu, Youngtak Sohn

We prove a Parisi formula for Ising and spherical perceptrons with Gaussian disorder and i.i.d. random potentials having a common Lipschitz bound and integrable values at zero. We assume $M/N\to\alpha\in(0,\infty)$ , where $M$ is the number of Gaussian vectors and $N$ is the number of spins. The proof combines cavity in $M$ and $N$ with the Aizenman–Sims–Starr scheme for the lower bound and Guerra’s interpolation for the upper bound. As consequences, we answer several problems posed by Talagrand (2011) and establish a quenched large deviation principle for the empirical distribution of the Gaussian projections, resolving a conjecture of Bolthausen and Kistler (2010). We also resolve the sharp-threshold conjecture of Aubin, Perkins, and Zdeborová (2019) for the $u$ -function binary perceptron at every positive width, and establish the predicted variational formulas for the entropy and capacity of the negative spherical perceptron. Finally, the zero-temperature limit yields the scalar projection-pursuit formulas conjectured by Montanari and Zhou (2025, 2026), in both the supervised and unlabelled settings.

Primarily AI-generated textHuman understanding: some parts

Oct 08, 2026PDF ↗View work →

hexagon:2610.00153v1

math.NT — Number Theory

The generalized Fermat equation $x^2+y^5=z^7$

Contributed by Manvir Jaswal

We show that the equation $x^2+y^5=z^7$ has no solution in nonzero coprime integers, assuming a classification theorem from Putz's thesis, which has not appeared in a refereed journal. Equivalently, none of the equations $x^2+y^5=z^7$ , $x^2+y^7=z^5$ , $x^5+y^7=z^2$ has a solution in nonzero coprime integers. Putz attaches to a solution an octic algebra, the fibre of a Belyi map of degree $8$ , and proves that it is always isomorphic to one fixed octic field $L_8$ . We prove unconditionally that no solution has fibre isomorphic to $L_8$ , by a fifth-power descent over a field $L_{24}$ of degree $24$ that Putz introduced, completed by fifth-power residue symbols at five auxiliary primes. We also prove, without assuming the generalized Riemann hypothesis, that $L_{24}$ has class number $1$ , using a criterion of Belabas, Diaz y Diaz and Friedman.

Primarily AI-generated textHuman understanding: no parts

Oct 08, 2026PDF ↗View work →

hexagon:2610.00152v1

cs.CC — Computational Complexity

A Verified Constructive Reduction of the Cook-Levin Theorem in Lean 4: Bridging the Gap Between Complexity Theory and Formal SAT Encodings

Contributed by Jonathan 𝑓(n) Reed

While the Cook-Levin theorem is fundamental to computational complexity, formalizations in proof assistants often rely on high-level arguments rather than constructing the concrete SAT formula. Within the Lean community, a rigorous, constructive reduction from Turing machines to SAT is currently absent from \texttt{mathlib}. We present a complete, machine-checked formalization in Lean 4 that addresses this gap by providing a constructive reduction from a deterministic Turing Machine model to a CNF formula. By rigorously defining the interface between the high-level computation model and the low-level SAT encoding, we bridge the gap between theoretical complexity and practical SAT-based verification. Our work specifically handles the challenges of verified 3D-variable indexing, injective mapping proofs, and global soundness, providing a verified tool for both communities to interact.

A mix of human-written and AI-generated textHuman understanding: all partsConjunctive Normal FormConstructive ReductionCook-Levin TheoremInteractive Theorem ProvingLean 4SAT EncodingsSatisfiability CheckingSymbolic ComputationTuring Machineformal verification

Oct 08, 2026PDF ↗View work →

hexagon:2610.00151v1

math.CO — Combinatorics

Square-difference-free sets of exponent 0.7580758

Contributed by Eric Naslund

Let $D(N)$ be the largest cardinality of a subset of $\{1,\ldots,N\}$ containing no two elements whose difference is a nonzero perfect square. We give a computer-assisted construction proving $D(N)\ge N^{0.7580758318008816-o(1)}$ , improving the exponent $0.752796455874514\ldots$ of Krachun's ranked-block construction. The residues we use carry subintervals of $[0,1]$ that are ordered along every modular square difference. A finite stopping-word argument shows that if finitely many such alphabets, in pairwise coprime perfect-square moduli, have interval moments whose contributions sum to more than $\alpha$ , then $\alpha$ is an attainable exponent. Krachun's prime chains reproduce his exponent in this framework. The gain comes from an alphabet modulo a power of $4$ , built by a $25$ -state recursion, and from two composite alphabets, at the primes $5,43$ and at $19,23$ , in which the first differing digit is read separately at each prime. The numerical conclusion is computer-assisted. The theorem, including every finite certificate, is formalized in lean, PALOMAR-2026-09-19-000006 v2.

Primarily AI-generated textHuman understanding: some parts

Oct 08, 2026PDF ↗View work →

hexagon:2610.00148v1

math.DS — Dynamical Systems

Uniform Kazhdan Monsters and Schmidt's Property M

Contributed by Mehdi Moradi

Let $G$ be an infinite finitely generated group whose proper subgroups are finite. We prove that a positive Kazhdan constant uniform over all finite generating sets forces every unit vector in every representation without invariant vectors to have a cofinite displacement gap. For ergodic probability-measure-preserving actions this gives \[ \liminf_{g\to\infty}\mu(gA\mathbin\triangle A) \geq \ku(G)^2\mu(A)(1-\mu(A)), \] and hence Schmidt's Property~ $M$ . A tensor-square argument also gives a uniform gap from modulus one for diagonal matrix coefficients. Conditional on the graded-diagram package underlying the Osin--Sonkin construction, the theorem shows that their infinite finitely generated simple ICC group of bounded exponent has Property~ $M$ . We include a corrected, constant-tracked proof of the Osin--Sonkin deduction from that package and conclude with questions about Ozawa's quasifinite Kazhdan quotients.

Primarily AI-generated textHuman understanding: some parts

Oct 07, 2026PDF ↗View work →

hexagon:2610.00146v1

math.AP — Analysis of PDEs

Phase retrieval for stationary Schrödinger evolutions

Contributed by Ben Pineau, João Pedro Ramos, Mitchell A. Taylor

We prove three phase-retrieval results for stationary one-dimensional Schr\"odinger evolutions. Masuda's unique-continuation theorem yields phase retrieval for finite-energy solutions and a broad class of semibounded potentials which may grow at infinity. For real potentials in the Faddeev class $L^1_1(\mathbb R)$ , measurements on all of spacetime determine arbitrary $L^2$ initial data. If the potential is smooth and compactly supported to the left of a point, measurements on the exterior half-line to its right suffice.

Primarily AI-generated textHuman understanding: all partsPhase retrievalSchrödinger equationUnique continuation

Oct 07, 2026PDF ↗View work →

hexagon:2610.00147v1

math.PR — Probability

Moment defects and sharp iid Berry–Esseen bounds

Contributed by Kacper Rodziewicz, Bartosz Kołodziejek

The known sharp third-moment inequality supplies an exact defect that identifies the standardized two-point family and controls transport and characteristic functions. We develop the corresponding Fourier reduction and give the qualitative eventual upper-bound argument. A penalized extremal problem yields eventual two-point optimality and a uniform linear deficit, with sharp cubic Wasserstein stability. A fifth-order lattice saddle gives the full oscillatory $n^{-2}$ correction for the optimal constants. A separate effective argument proves $C_n<C_{\mathrm E}$ for every $n\ge49$ , by a finite base and a first-failure induction. Exact polynomial certificates give bounds for two and three summands; a complete interval argument treats all three-point laws at four summands. An elementary historical bound $C\le0.45$ is included as an appendix. ChatGPT and Codex assisted the development of the proofs and computational certificates and the preparation of this manuscript, using the GPT-5.6 Sol, GPT-6.1 Sol and GPT-6 Astra models.

Primarily AI-generated textHuman understanding: some parts

Oct 07, 2026PDF ↗View work →

hexagon:2610.00145v1

math.RT — Representation Theory

The inverse quiver problem is NP-complete

Contributed by Paul, Marin, Pierre Coutant--Denord

We prove that the inverse quiver problem is NP-complete. We also present a new proof that the quiver problem is NP-complete. We present a way to translate arithmetical/algebraic geometry problems in terms of (inverse) quiver problem.

Primarily human-written textHuman understanding: all partsQuiver representation

Oct 07, 2026PDF ↗View work →

hexagon:2610.00142v1

math.FA — Functional Analysis

Noncommutative Buzano-Dragomir Inequality and Applications

Contributed by K. MAHESH KRISHNA

Dragomir [\textit{Bull. Aust. Math. Soc., 2016}] showed that the Buzano inequality holds for orthogonal projections on Hilbert spaces. Dragomir [\textit{Linear Multilinear Algebra, 2016}] also derived the most general form of the Buzano inequality for bounded linear operators on Hilbert spaces. We show that Dragomir result extends to adjointable morphisms on Hilbert C*-modules. Using this generalization, we derive bounds for the roots of polynomials over commutative unital C*-algebras. We formulate the notion of noncommutative numerical range and derive numerical radius bounds for self-adjoint morphisms on Hilbert C*-modules over unital C*-algebras. We formulate several open problems, including the noncommutative Toeplitz-Hausdorff, von Neumann inequality, Ando inequality, Berger power dilation, Kittaneh inequality, Crouzeix problems.

Primarily human-written textHuman understanding: all partsBuzano InequalityCrouzeix inequality.Hilbert C*-modulesNumerical radiusPolynomial roots

Oct 07, 2026PDF ↗View work →

hexagon:2610.00141v1

math.AG — Algebraic Geometry

Constant-Time O(1) AST Reduction and Native Delegate Compilation in RICIS-III

Contributed by Дмитрий Алейников

Traditional Computer Algebra Systems (CAS) and dynamic expression interpreters evaluate critical points and mathematical singularities via runtime limit approximations, Taylor series expansions, or recursive L'Hôpital routines. These procedures incur an unresolvable computational bottleneck: dynamic tree-traversal complexity of O(N) alongside runtime branching hazards and undefined IEEE-754 states (NaN, division-by-zero traps). This paper presents a formal engineering proof of how the Recursive Indexed Calculus of Identity and Singularity (RICIS-III v7.9) enables strict constant-time O(1) symbolic Abstract Syntax Tree (AST) reduction and native machine delegate compilation. By enforcing Absolute Continuity (L₀), the Identity Principle (L₁), Safety Protocols (SP₁–SP₅), Protocol P₁ (direct structural evaluation substituting lim(x→a) with x=a), and the geometric realization of Axiom A₆ (S_F ⊠ I_G → R(F,G) →_μ F · G), all indeterminate nodes are eliminated during symbolic pre-compilation. The resulting pruned AST compiles into straight-line native execution blocks (such as .NET CLR dynamic delegates or LLVM IR) operating in deterministic O(1) clock cycles per tick with zero runtime branching.

Primarily human-written textHuman understanding: all parts

Oct 07, 2026PDF ↗View work →

hexagon:2610.00143v2

math.RT — Representation Theory

A note on counterexamples to homological conjectures

Contributed by 琪越唐

Building on the constructions of OpenAI, we extend these constructions to any base field containing an element of infinite multiplicative order. Over each such field, we obtain finite-dimensional algebras giving counterexamples to both Tachikawa conjectures, the Auslander–Reiten conjecture, the Gorenstein-projective conjecture, the Nakayama, generalized Nakayama, and strong Nakayama conjectures, the Auslander–Gorenstein conjecture, the little and big finitistic dimension conjectures, and the Wakamatsu tilting conjecture.

A mix of human-written and AI-generated textHuman understanding: no partsRepresentation theory

Oct 07, 2026PDF ↗View work →

hexagon:2610.00140v4

math.RT — Representation Theory

A note of refinements to an algebra of infinite little finitistic dimension

Contributed by 琪越唐

Building on OpenAI’s An algebra of infinite little finitistic dimension, we simplify the exposition and extend the construction to every field. 2026/10/10：We have added formal verification：https://github.com/tqyqiqi1509/Note198-formalization

A mix of human-written and AI-generated textHuman understanding: no partsRepresentation theory

Oct 07, 2026PDF ↗View work →

hexagon:2610.00138v1

math.AT — Algebraic Topology

Weak chromatic splitting fails at n = p for every odd prime p

Contributed by Agnes Beaudry, Tomer Schlank

We prove that for every odd prime $p$ there is a height $n$ for which the map $L_{n-1}S_p \to L_{n-1}\L_{K(n)}S_p$ is not injective on homotopy groups, hence not the inclusion of a wedge summand. In particular, for such pairs $(n,p)$ the weak chromatic splitting conjecture is false. More precisely, we prove the conjecture fails for $(n,p) = (3,3)$ and for all pairs $(n,p)$ with $p \le n < \sqrt{2}(p-1)$ . In particular, the conjecture fails for $(n,p) = (p,p)$ for every odd prime $p$ . This disproof was produced autonomously by Claude in a session working on Freyd's generating hypothesis with no human in the loop. This note is a human write-up of the disproof. We did not contribute any ideas.

Primarily human-written textHuman understanding: all parts

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hexagon:2610.00137v1

math.NT — Number Theory

Proof of the Non-existence of Perfect Cuboids via Mordell-Weil Rank Exhaustion and Minimal Polynomial Irreducibility of the Perfect Cuboid Surface

Contributed by Jonathan 𝑓(n) Reed

This manuscript establishes the non-existence of the Perfect Cuboid---a rectangular parallelepiped with integer edges, face diagonals, and space diagonal. By performing a rational sectioning of the governing quadratic forms, we demonstrate that the problem reduces to finding a non-trivial rational point on a family of hyperelliptic curves of Genus 3. We prove that the Jacobian of these curves possesses a Mordell-Weil rank of zero and that the perfection locus is an irrational algebraic singularity of degree $d = 4$ , precluding any solution in the integer domain $\mathbb{Z}^3$ . The non-existence of rational solutions is further verified via formal methods in Lean 4, demonstrating that the intersection of the Mordell-Weil torsion set and the degree-4 perfection locus is empty.

A mix of human-written and AI-generated textHuman understanding: all parts2-DescentEuler BrickHyperelliptic CurvesInteractive Theorem ProvingJacobian VarietyLean 4Mordell-Weil RankPerfect CuboidQuadratic Residueformal verification

Oct 07, 2026PDF ↗View work →

hexagon:2610.00136v2

math.NT — Number Theory

The generalized Fermat equation $x^3+y^3=z^n$

Contributed by Manvir Jaswal

We prove that the equations $x^3+y^3=z^n$ and $x^3+y^3=3z^n$ have no solution in coprime nonzero integers for any $n\ge3$ . For the first equation the open cases were prime exponents $p\equiv1\pmod 3$ above $10^9$ outside a set of congruence classes treated by Chen and Siksek; in these cases the solution $1^3+2^3=3^2$ blocks the modular method. We replace Kraus's Frey curve by a hypergeometric motive of rank three over $K=\mathbb{Q}(\sqrt{-3})$ , whose parameter at a solution is $3$ -adically close enough to a point of maximally unipotent monodromy for inertia at $\sqrt{-3}$ to act unipotently; the parameter of $1^3+2^3=3^2$ is not. By a theorem of Calegari, Emerton and Gee, the mod $p$ representation of the fiber, twisted by a cubic character, is the reduction of a member of a compatible system of minimal ramification, and we show that the member at a prime above $3$ is irreducible and ordinary at $\sqrt{-3}$ . Ramification and unconditional discriminant bounds show that its reductions have trivial semisimplification, and as the Galois group of the maximal pro- $3$ extension of $K$ unramified outside $\sqrt{-3}$ is generated by one inertia group, the member stabilizes its ordinary line, a contradiction. For $x^3+y^3=3z^n$ the same argument also works at the primes $p\equiv2\pmod3$ , which are inert in $K$ , and Frey curves and descents treat the remaining exponents.

Primarily AI-generated textHuman understanding: no partsFrey representationscompatible systems of Galois representationsgeneralized Fermat equationhypergeometric motivesmodular method

Oct 07, 2026PDF ↗View work →

hexagon:2610.00135v1

math.NT — Number Theory

Improved sum-difference inequalities in abelian groups

Contributed by Logan Kleinwaks

For all finite subsets $X,Y$ of an abelian group, we prove \[ |X-Y|\le |X+Y|^{\lamI},\qquad \lamI=\frac{9451\e-3286}{5378\e+787}=1.454277448906\ldots, \] improving the classical exponent $3/2$ . We also prove that a universal two-set exponent $\lambda$ over the integers implies an upper bound $2-1/\lambda$ for the Gyarmati--Hennecart--Ruzsa constant, the supremum $\theta^*$ of $t$ such that $|A-B|\gg|A+B|^t$ and $|A+B|\ll|A|$ for arbitrarily large $A,B\subset\Z$ . Consequently, \[ \theta^*\le\frac{13524\e-7359}{9451\e-3286}=1.312373302115\ldots, \] improving their bound $4/3$ . The first argument combines a coupling with distinct differences, entropy inequalities for independent sums, a finite certificate using non-Shannon inequalities, and an explicit limiting certificate with weights $\int_0^1t(1-t)^k\e^t\,dt$. The transfer uses localisation and the Pl\"unnecke--Ruzsa inequality over a sequence of scales. The proofs are formalised in Lean~4.

Primarily AI-generated textHuman understanding: some partsShannon entropydifference setsformal verificationnon-Shannon inequalitiessumsets

Oct 07, 2026PDF ↗View work →

hexagon:2610.00134v2

math.OA — Operator Algebras

Poisson boundaries of type III factors and the relative bicentralizer conjecture

Contributed by Shuoxing Zhou

We develop the Poisson boundary theory for general von Neumann algebras with separable preduals. As applications, we generalize and give new proofs of the results on the weak Dixmier property for inclusions with expectations or operator-valued weights \cite{Pop99,Mar19,Iso25}. We also prove that every continuous factor admits irreducible embeddings into the hyperfinite factors of type $\mathrm{III}_\lambda$ , $0<\lambda\leq1$ , and into some hyperfinite factor of type $\mathrm{III}_0$ . Finally, using the Poisson boundary techniques developed above, we prove that for every inclusion with faithful normal conditional expectation $M\subset N$ , $M\subset c(N)$ has the weak Dixmier property. By Marrakchi's characterization \cite[Theorem~D]{Ma25}, this gives the relative bicentralizer conjecture for von Neumann algebras with separable preduals.

A mix of human-written and AI-generated textHuman understanding: all parts

Oct 06, 2026PDF ↗View work →

hexagon:2610.00083v1

math.QA — Quantum Algebra

Strongly positive bases and quantum greedy expansions

Contributed by 琪越唐

We prove that every element of a strongly positive basis of a coefficient-free rank-two quantum cluster algebra has nonnegative Laurent-polynomial coefficients in the quantum greedy basis. This establishes the strongly positive basis assertion of Conjecture 16 of Lee, Li, Rupel, and Zelevinsky. We also give a counterexample to their Conjecture 13(b).

A mix of human-written and AI-generated textHuman understanding: some partsquantum cluster algebra

Oct 06, 2026PDF ↗View work →

hexagon:2610.00031v1

math.RA — Rings and Algebras

Algebraic dependence of cluster X-variables

Contributed by 琪越唐

We prove that, over any field and with algebraically independent initial seed coordinates, two cluster $X$ -variables are algebraically dependent if and only if they are equal or reciprocal. In characteristic zero, this is equivalent to the vanishing of the wedge product of their differentials.

A mix of human-written and AI-generated textHuman understanding: some partsCluster Algebra

Oct 05, 2026PDF ↗View work →

hexagon:2610.00032v1

math.RA — Rings and Algebras

An explicit nonideal rooted cluster morphism

Contributed by 琪越唐

We give a counterexample to Chang and Zhu’s question of whether every explicit rooted cluster morphism is ideal.

A mix of human-written and AI-generated textHuman understanding: some partsCluster Algebra

Oct 05, 2026PDF ↗View work →

hexagon:2610.00030v1

math.AG — Algebraic Geometry

Crystalline and infinitesimal Poisson stacks

Contributed by Aleksandr Karapetyan

A systematic way to construct Poisson brackets on moduli stacks in algebraic geometry is through shifted Poisson structures on derived stacks. The standard construction, due to Calaque--Pantev--To{\"e}n--Vaqui{\'e}--Vezzosi, imports Gelfand--Kazhdan formal geometry to derived stacks in order to establish formal descent for polyvector fields. The result is a graded Lie algebra which we call the ``crystalline'' polyvector fields on a derived stack. Using instead the formal derived geometry machinery of Gaitsgory--Rozenblyum, we construct a graded Lie algebra of ``infinitesimal'' polyvector fields which has a direct geometric interpretation: it governs deformations of the formal shifted cotangent stack, together with its canonical exact symplectic form. Our main result is an equivalence between crystalline and infinitesimal polyvector fields on a derived stack as graded Lie algebra objects, providing a deformation-theoretic perspective on the graded Lie algebra constructed by Calaque--Pantev--To{\"e}n--Vaqui{\'e}--Vezzosi.

Primarily human-written textHuman understanding: all partsDerived algebraic geometrydeformation theoryderived algebrainfinity-categoriesshifted Poisson structuresshifted symplectic structures

Oct 04, 2026PDF ↗View work →

hexagon:2610.00029v1

math.QA — Quantum Algebra

Theta Bases for Rank-Two Quantum Cluster Algebras of Geometric Type

Contributed by 琪越唐

We prove that quantum theta and greedy bases coincide in coefficient-free rank two for all positive exchange parameters. Their homogeneous lifts form integral theta bases for arbitrary geometric coefficients and compatible integral quantizations, with frozen variables inverted. For nonnegative initial coefficient blocks, we also establish the basis theorem without frozen inverses.

Primarily AI-generated textHuman understanding: no partsquantum cluster algebra

Oct 04, 2026PDF ↗View work →

hexagon:2610.00026v1

math.CO — Combinatorics

The Anti-Arithmetic Product of Symmetric Functions

Contributed by Darij Grinberg

The \emph{arithmetic product} $\boxdot$ is a bilinear operation on the ring of symmetric functions over $\mathbb Q$ defined by \[ p_\lambda \ \boxdot\ p_\mu = \prod_{i,j}p_{\operatorname{lcm}(\lambda_i,\mu_j)}^{\gcd(\lambda_i,\mu_j)} \] on the power-sum basis $(p_\lambda)$ . It is known that this operation preserves the subring $\mathbf{Symm}_{\mathbb Z}$ of symmetric functions with integer coefficients, and is Schur-positive on pairs of Schur functions. Indeed, it corresponds to induction of representations from $S_n \times S_m$ to $S_{nm}$ . In this work, we consider the \emph{anti-arithmetic product} $\diamondsuit$ , which is defined by the same formula but with $\gcd$ and $\operatorname{lcm}$ interchanged. We show that it, too, preserves $\mathbf{Symm}_{\mathbb Z}$ , even though it lacks the Schur positivity property. This was conjectured on MathOverflow in 2014. Our method is a more intricate variant of the representation-theoretical interpretation of $\boxdot$ . The anti-arithmetic product does not correspond to an operation on actual representations; but its adjoint can still be described as a map on characters, which (as we show) is a $\lambda$ -ring morphism from the character ring of $S_{mn}$ to that of $S_m \times S_n$ . Now, a 1975 theorem of Boorman shows that the representation ring of $S_n$ is generated by the natural permutation representation $M_n = \mathbb Q^n$ as a $\lambda$ -ring. Thus, the proof of integrality boils down to only computing the image of $M_{mn}$ under this adjoint, which can be done using M\"obius inversion in the representation ring. This work is aimed at readers familiar with representation rings and the representation theory of symmetric groups. No prior knowledge of $\lambda$ -rings is presumed. Three self-contained proofs of Boorman's theorem are given in the appendices, two of them lifting the theorem to the noncommutative symmetric functions (or Solomon's descent algebra), recovering a result of Schocker.

A mix of human-written and AI-generated textHuman understanding: all partsSpecht modulesdescent algebralambda-ringsnoncommutative symmetric functionssymmetric functionssymmetric group representations

Oct 03, 2026PDF ↗View work →

hexagon:2610.00024v1

math.RT — Representation Theory

Reflexive equivalence and reflexive-minimal algebras

Contributed by Haruhisa Enomoto

Let $A$ be a finite-dimensional algebra over a field. A finite-dimensional algebra $B$ over the same field is called reflexively equivalent to $A$ if their categories of reflexive modules are equivalent. We prove that there is a basic algebra $A_{\min}$ , unique up to isomorphism, such that $B$ is reflexively equivalent to $A$ if and only if $B\cong\operatorname{End}_{A_{\min}}(A_{\min}\oplus X)$ for some reflexive $A_{\min}$ -module $X$ . Moreover, we compute $A_{\min}$ explicitly. We extend these results to module-finite algebras over henselian local rings of dimension at most one under a dominant dimension condition at minimal primes. We also introduce reflexive modules over additive categories and prove that taking reflexive modules is idempotent: the reflexive modules over the category of reflexive modules form an equivalent category. As an application, we show that reflexive equivalence classes of algebras with finitely many indecomposable reflexive modules correspond bijectively to Morita equivalence classes of algebras whose reflexive modules are projective.

Primarily AI-generated textHuman understanding: some parts

Oct 03, 2026PDF ↗View work →

hexagon:2610.00025v2

math.QA — Quantum Algebra

Minimality of the Rank-Two Quantum Greedy Basis

Contributed by 琪越唐

We prove that the rank-two quantum greedy basis is the least strongly positive basis when b | c or c | b, resolving Conjecture 14 of Lee–Li–Rupel–Zelevinsky. Every strongly positive basis has nonnegative expansion coefficients in the greedy basis.

A mix of human-written and AI-generated textHuman understanding: some partsquantum cluster algebra

Oct 03, 2026PDF ↗View work →

hexagon:2610.00023v1

math.QA — Quantum Algebra

A Finite Polyhedral Construction of the Rank-Two Quantum Greedy Basis

Contributed by 琪越唐

We give a finite polyhedral construction of the quantum greedy basis for coefficient-free rank-two quantum cluster algebras. The construction specializes coefficientwise to the classical polyhedral construction at v = 1. Corresponding classical and quantum coefficients and auxiliary margins have identical zero sets, and the Newton polytopes are affine images of the classical carriers.

A mix of human-written and AI-generated textHuman understanding: some partsquantum cluster algebra

Oct 03, 2026PDF ↗View work →

hexagon:2610.00022v2

math.OC — Optimization and Control

Continuity of solutions to abstract linear control systems

Contributed by Frédéric Marbach

It has long been known that the solutions to abstract linear control systems are continuous in time for controls in $L^p$ with $1 \le p < \infty$ . We prove that the same property remains valid for the endpoint case $p = \infty$ , giving a positive answer to Weiss' 1989 Problem 2.4. The proof relies on a direct semigroup argument based on Phillips' lemma, does not require the input map to have an integral representation (which is not always the case for $p = \infty$ ), and actually entails that such systems are all of the zero-class (which fails for $1 \le p < \infty$ ).

Primarily AI-generated textHuman understanding: all partsabstract linear control systems

Oct 03, 2026PDF ↗View work →

hexagon:2610.00019v1

math.PR — Probability

The Negative Spherical Perceptron: Capacity, Isostatic Jamming, and Full Replica Symmetry Breaking

Contributed by P. M. Aronow, Patrick Lopatto

We study the negative spherical perceptron, a mean-field model of jamming with a nonconvex solution space. We establish the Parisi formula for its free energy and identify the capacity for every constraint density $\alpha>2$ . We also show that the jamming point is isostatic: optimal configurations have exactly $N$ contacts. For $\alpha$ slightly above two, we show that replica symmetry is lost at the de Almeida–Thouless margin through a continuous transition to full replica symmetry breaking. Further, we show that Gardner's formula overestimates the capacity by order $(\alpha-2)^3$ .

Primarily AI-generated textHuman understanding: some partsperceptronspin glass

Oct 02, 2026PDF ↗View work →