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619 works

hexagon:2611.00019v1

math.NT — Number Theory

Minimal recurrences for binomial power sums

Contributed by Khai-Hoan Nguyen-Dang

For every positive integer $r$ , we prove that the least order of a polynomial-coefficient recurrence for $F_r(n)=\sum_{k=0}^n\binom nk^r$ is $\lfloor(r+1)/2\rfloor$ . This establishes the unrestricted minimal-order assertion arising from Franel's work of 1894--1895. We also determine the least order $\lfloor r/2\rfloor$ , for $r\geq2$ , of the alternating sums $(-1)^n\sum_{k=0}^{2n}(-1)^k\binom{2n}{k}^r$ . The lower bounds follow from real moment representations: every nonzero singularity of the representing measure forces a root of the leading characteristic polynomial of the recurrence. A common reflection argument gives telescoping recurrences attaining both bounds. For the ordinary sums, we combine the deformation of Straub and Zudilin with a shifted prime-power congruence to prove that the minimal shift operator is irreducible over $\C(n)$.

A mix of human-written and AI-generated textHuman understanding: some partsAp\'ery limitsFranel numbersFranel’s recurrence problembinomial power sums

Nov 02, 2026PDF ↗View work →

hexagon:2611.00017v1

math.AG — Algebraic Geometry

Gersten injectivity and Morel's purity conjecture

Contributed by Niels FELD

Morel conjectured that the $\mathbb{A}^1$ -homotopy sheaves of an $S^1$ -spectrum built from suspension spectra of smooth projective schemes are pure; one condition in purity is injectivity of restriction to dense open subschemes. Over a regular base $S$ , we show that this injectivity condition, for the homotopy sheaves of algebraic $K$ -theory with coefficients in an arbitrary spectrum, is equivalent to Gersten injectivity at the henselizations of all local rings of smooth $S$ -schemes; and that these $K$ -theory spectra are pure in Morel's sense. Hence every henselian regular local ring at which Gersten injectivity fails, integrally, rationally, or with finite coefficients, gives a counterexample to Morel's conjecture. The author's finite-coefficient counterexample over $\mathbb{Z}_3[[x,y]]/(3+x^2-y^3)$ therefore disproves the conjecture, already over the regular scheme $\operatorname{Spec}\mathbb{Z}[1/2][x,y]/(3+x^2-y^3)$ . Recently announced integral and rational Gersten counterexamples, including unpublished work of the author, would show, if confirmed and if they persist after henselization, that the conjecture fails already for the $K$ -theory spectrum itself.

Primarily AI-generated textHuman understanding: all parts$S^1$-spectraGersten conjectureMotivic homotopy theoryalgebraic $K$-theoryhenselizationpure sheaves

Nov 02, 2026PDF ↗View work →

hexagon:2611.00016v1

math.CO — Combinatorics

The ten minimum universal sets of MacMahon cubes

Contributed by Jason Davies

A collection of six-coloured MacMahon cubes is universal if eight of its cubes can be selected to build a $2\times2\times2$ model of any target variety, with matching exterior colours and no internal matching requirement. We prove that exactly ten labelled collections attain the known minimum size of twelve, even when repeated varieties are allowed, resolving the conjectures of Johnson and Roldán. Usable-cube inequalities force a symmetric multiplicity matrix with row and column sums two; corner coverage then forces two disjoint triangles in Conway's tableau. The written proof is elementary and requires no exhaustive search. The classification and its discrete geometric interpretation are formalised in Lean 4. Exhaustive computation provides a separate check and additional target-count distributions.

Primarily AI-generated textHuman understanding: some partsConway's tableauEight Blocks to MadnessLean 4MacMahon cubesuniversal sets

Nov 02, 2026PDF ↗View work →

hexagon:2611.00015v1

math.CO — Combinatorics

Positive polytopes and the full Fock–Goncharov conjecture

Contributed by Qiyue Tang

We prove the origin-interior form of the polytope criterion of Gross, Hacking, Keel and Kontsevich: over a field of characteristic zero, full Fock–Goncharov for a principal coefficient cluster variety is equivalent to the existence of a bounded full-dimensional positive polytope containing the origin in its interior. Replacing the interior condition by membership of the origin gives a false criterion.

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

Nov 02, 2026PDF ↗View work →

hexagon:2611.00014v1

math.CV — Complex Variables

The Möbius pseudodistance of the annulus and an improved lower bound for Korenblum's constant

Contributed by David Niedbala Giraudin

We show that Korenblum's constant of the Bergman space satisfies $c_2\ge 0.446$ . The best published lower bound was $c_2\ge 0.4263$ (Wikström, 2026). The new ingredient is a closed form, in Jacobi theta functions, of the Möbius pseudodistance of the annulus $\{c<|z|<1\}$ between two points of the same centred circle. It separates the variables and yields three monotonicity properties, one of which, a profile inequality, combined with Kirszbraun's theorem in the hyperbolic plane, improves the constant in Wang's annular estimate. Wikström's dual moment criterion is then verified at $c=223/500$ for an explicit measure with fourteen rational atoms, in rigorous arithmetic, by a self-contained verifier. The French version of this note is dated 21 October 2026.

Primarily AI-generated textHuman understanding: no partsBergman spaceKirszbraun theoremKorenblum's constantMöbius pseudodistancecomputer-assisted proofmaximum principlemoment dualitytheta functions

Nov 02, 2026PDF ↗View work →

hexagon:2611.00013v1

math.QA — Quantum Algebra

Projected stated (SL_n)-skein algebras and the Huang–Wang conjectures

Contributed by Qiyue Tang

We prove Conjectures 1.5 and 1.6 of Min Huang and Zhihao Wang: the projected stated (SL_n)-skein algebra equals its quantum cluster and upper cluster algebras, and the specified exchangeable variables generate it over the frozen Laurent coefficient algebra. The results hold for triangulable unpunctured marked surfaces with at least two boundary marked points per connected component, over every coefficient domain and parameter in the conjectures.

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

Nov 02, 2026PDF ↗View work →

hexagon:2611.00012v1

math.GT — Geometric Topology

A certified upper bound for the distortion of the trefoil knot

Contributed by David Niedbala Giraudin

The distortion of a rectifiable closed curve $\gamma\subset\mathbb R^3$ is the supremum, over pairs of distinct points, of the ratio of the length of the shorter arc of $\gamma$ between them to their distance; the distortion $\delta(K)$ of a knot type $K$ is the infimum over all curves of type $K$ . For the trefoil, the published lower bound is $\delta\ge5\pi/3$ , valid for every non-trivial knot (a recent preprint claims $\delta>6.5321$ ), and the only upper bound we found in the literature is the value $7.16$ obtained by numerical simulation. We exhibit an explicit polygon with $192$ vertices, of knot type trefoil, whose distortion is at most $6.92$ . The proof is computer-assisted: the knot type is certified by an explicit piecewise-linear path of embedded polygons starting from a polygon on a torus, and the distortion by exact rational arithmetic on every pair of edges. Two separately written verifiers are supplied.

Primarily AI-generated textHuman understanding: no partsGromov distortioncomputer-assisted proofknot distortionpolygonal knotstrefoil

Nov 02, 2026PDF ↗View work →

hexagon:2611.00011v1

math.MG — Metric Geometry

Improved and sharp bounds for illumination

Contributed by אלון שכטר

We prove improved ordinary illumination bounds and exact ordinary and fractional values for several classes of convex bodies. Every full-dimensional complex zonotope in $\C^2$ has illumination number five, except complex affine images of the bidisc, whose number is seven. For complex $1$ -symmetric non-polydiscs in $\C^3$, an explicit construction gives twelve illuminating directions. For real $1$ -symmetric non-cubes in $\R^n$ , connected domination in the cube graph gives the upper bound $2^{n-1}+\gamma_c(Q_{n-1})+n-1 =2^{n-1}(1+(1+o(1))/n)$; an explicit family has illumination number $2^{n-1}$ . We also give a product boundary measure proving fractional lower bounds $2^n$ for bodies between specified inner and outer bodies, and attain these bounds along Minkowski interpolations with a positive inner summand. Finally, the least size $U_n$ of a single family illuminating every normalized complex $1$ -unconditional body satisfies $U_n\sim3^{n+1}/\sqrt{\pi n}$ .

Primarily AI-generated textHuman understanding: no partsconvex geometry

Nov 02, 2026PDF ↗View work →

hexagon:2611.00010v1

math.MG — Metric Geometry

Illumination of complex 1-unconditional convex bodies

Contributed by אלון שכטר

We study ordinary and fractional illumination of complex $1$ -unconditional convex bodies. In every complex dimension $n$ we give an explicit ordinary bound asymptotic to $3^{n+1}/\sqrt{\pi n}$ , and prove $\ill^*(K)\le b_*^n$ and $\ill(K)=O(n\log(n+1)b_*^n)$, where $b_*=2.4805534697\ldots$ is defined by an explicit scalar equation. For normalized non-polydiscs in dimensions two, three and four, the sharp ordinary bounds are $6$ , $14$ and $30$ . More generally, a full coordinate $(n-1)$ -polydisc gives the sharp bound $2^{n+1}-2$ in every dimension $n\ge2$ . In dimension two we prove the fractional bound $4$ and classify equality by the two maximal supporting coefficients at the coordinate axes. If every extreme point has all coordinates nonzero, we obtain the fractional bound $2^n$ , with equality exactly for the polydisc, and a quantitative strict bound otherwise. Appendices give the exact sizes of simultaneous illuminating families in dimensions one through five, the exact finite verification used in dimension four, and a numerical comparison of the general estimates through dimension $100$ .

Primarily AI-generated textHuman understanding: some partsconvex geometry

Nov 02, 2026PDF ↗View work →

hexagon:2611.00009v1

math.NT — Number Theory

On Problem 5 of Vitorino and Vukusic: $\sup_{k\ge 0} B(2^k\alpha)\ge 12$

Contributed by David Niedbala Giraudin

For an irrational $\alpha$ let $B(\alpha)=\limsup_n a_n(\alpha)$ be the upper limit of its partial quotients. Vitorino and Vukusic proved $\sup_{k\ge 0}B(2^k\alpha)\ge 5$ for every irrational $\alpha$ and asked, as their Problem 5, for an improvement. We prove $\sup_{k\ge 0}B(2^k\alpha)\ge 12$ . The proof is a finite computation organised around an invariant $N(C)$ : the least number of doubling levels at which the recurrent kernel of a synchronous product of Raney transducers becomes a finite union of pure cycles. We show that $N(C)$ is intrinsic, that $N(C)<\infty$ for every $C$ would imply the $2$ -adic Littlewood conjecture, and that $N(C)=\infty$ is equivalent to a rigidity failure; we compute $N(C)=1,1,3,5,5,8,15,21,29,30,31$ for $C=1,\dots,11$ . In the language of Badziahin's set LMad this settles a level-bounded form of his Problem B for $C\le 11$ . The cycles which survive are ideal classes of discriminant $D\equiv 1 \pmod 8$ whose whole $\mathfrak{p}_2$ -orbit has partial quotients at most $C$ ; we list them, and check the lists by an independent arithmetic route, in both directions for $D\le 10^5$ . The result concerns the upper limit $B$ only. On the side of the supremum $M$ it gives $\sup_k M(2^k\alpha)\ge 12$ , which is weaker than what is known: Vitorino and Vukusic prove $15$ , and Badziahin's bound $1/25$ yields $24$ . Two self-contained Python files, without external dependency, reproduce the table and the lists of discriminants; the table up to $C=8$ takes about fourteen seconds.

Primarily AI-generated textHuman understanding: no partsRaney transducerscomputer-assisted proofcontinued fractionsideal classesp-adic Littlewood conjecture

Nov 02, 2026PDF ↗View work →

hexagon:2611.00008v1

math.GT — Geometric Topology

Certified ropelength bounds for torus knots and the tight knot constant

Contributed by David Niedbala Giraudin

The tight knot constant $\alpha_0$ is the largest constant with $L(K)\ge\alpha_0\,\mathrm{Cr}(K)^{3/4}$ for every knot $K$ , where $L$ is the ropelength (unit-radius rope) and $\mathrm{Cr}$ the crossing number. We exhibit an explicit $C^{1,1}$ embedding of the torus knot $T(19,24)$ , with $\mathrm{Cr}=432$ , of thickness at least $1$ and length at most $939.984$ . Hence $\alpha_0\le 9.9200$ . The published bound is $10.76$ . The proof is computer-assisted: the knot type is certified by an explicit piecewise-linear path of embedded polygons starting from a polygon on a torus, and the thickness by exact integer and rational arithmetic. Two separately written verifiers are supplied, together with certificates for $T(14,17)$ and $T(11,14)$ .

Primarily AI-generated textHuman understanding: no partscomputer-assisted proofropelengththicknesstight knotstorus knots

Nov 02, 2026PDF ↗View work →

hexagon:2611.00007v1

math.MG — Metric Geometry

Illumination of several families of complex convex bodies

Contributed by אלון שכטר

We determine ordinary and fractional illumination numbers for complex Hanner bodies and for bodies obtained as convex hulls of coordinate polydiscs indexed by the maximal independent sets of a graph. The formulas are sums over coordinate supports. For Hanner bodies we classify all equality cases in the ordinary and fractional dimension bounds, including the sharp ordinary bound for non-polydiscs. For graph bodies, fractional equality $2^n$ occurs exactly when the graph is a disjoint union of isolated vertices and edges; a vertex of degree at least two gives the strict bound $3\cdot2^{n-2}$ . We also prove the fractional bound $2^n$ for bodies defined by nondecreasing submodular constraints on coordinate moduli. For finite systems of positive weighted inequalities satisfying an explicit condition on tight sets, we obtain the same fractional bound and an ordinary bound of $(2+o(1))n\log n\,2^n$ , together with an explicit estimate in every dimension. This includes bounded systems on laminar families with arbitrary positive coefficients. We conclude with a conjectural classification of fractional equality for normalized complex $1$ -unconditional bodies.

Primarily AI-generated textHuman understanding: some partsconvex geometry

Nov 02, 2026PDF ↗View work →

hexagon:2611.00006v1

math.RT — Representation Theory

Equality of the Mirković–Vilonen and theta bases

Contributed by Qiyue Tang

We prove Kamnitzer's ICM 2022 conjecture that the Mirković–Vilonen and theta bases coincide.

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

Nov 02, 2026PDF ↗View work →

hexagon:2611.00005v1

math.CO — Combinatorics

Coincidences of $q$ -analogues of Markoff numbers outside the known families: an answer to a question of Labbé, Lapointe and Steiner

Contributed by David Niedbala Giraudin

Labbé, Lapointe and Steiner proved that $w\mapsto\mu_q(w)_{12}$ is injective on Christoffel words, gave two families of identities showing that it is not injective on $\{\mathtt{0},\mathtt{1}\}^*$ , and asked whether every coincidence $\mu_q(x)_{12}=\mu_q(y)_{12}$ comes from these two families. We show that it does not. The smallest counterexamples have length $24$ ; by an exhaustive computation, among words of length at most $32$ there are exactly $50$ classes of coincidences not explained by the two families, $10$ of length $24$ and $40$ of length $30$ . Each of them contains an instance of one of a few new identities, which we prove for a generic $2\times2$ matrix in place of the matrix of a factor of the word. One of these identities belongs to an infinite family, indexed by $k\equiv1\pmod 4$ , which we prove for every such $k$ .

Primarily AI-generated textHuman understanding: no partsChristoffel wordsMarkoff numberscombinatorics on wordsq-analogues

Nov 02, 2026PDF ↗View work →

hexagon:2611.00004v1

cs.CC — Computational Complexity

A Sublinear Treewidth Exponent for Binary Constraint Satisfaction

Contributed by Troy Tri Nguyen

We give a deterministic algorithm for binary constraint satisfaction whose exponent in the input size is sublinear in treewidth on a class of graphs with unbounded treewidth. There are a class G of graphs of bounded maximum degree, a constant c, and a function f such that one algorithm correctly decides every binary CSP instance and, on instances I with primal graph G ∈ G, runs in time f(G) · ||I||^(c · tw(G) / sqrt(log tw(G))) . This contradicts the literal formulation of Conjecture 1.4 of Marx (2010). The algorithm follows from a domain-uniform counting bound: for every fixed maximum degree ∆, complete-table in- stances with k variables and domain size D ≥ 2 can be counted in time LO∆ (1)DO∆ (k/√log k) for suﬃciently large k. The constants are independent of D and of the constraint relations. We obtain this bound from the tensor-network recursion of Claude (Anthropic), and use attributed graph foundations from OpenAI to construct the required expander family. Support pruning connects the counting routine to sparse tuple-list inputs without expanding the original domain. The algo- rithm, its native finite-alphabet machine implementation, and the conjecture counterexample are formalized in Lean 4.

Primarily AI-generated textHuman understanding: some parts

Nov 02, 2026PDF ↗View work →

hexagon:2611.00003v1

math.OA — Operator Algebras

Noncommutative Cauchy Bound and Noncommutative Montel Bound for Roots of Polynomials

Contributed by K. MAHESH KRISHNA

In 1829, Cauchy derived an upper bound for every root of a complex polynomial using the maximum of the absolute values of the coefficients. In 1931, Montel derived an upper bound using the sum of the absolute values of the coefficients. We derive noncommutative versions of the Cauchy and Montel bounds.

Primarily human-written textHuman understanding: all partsBanach algebra.Cauchy boundMontel bound

Nov 02, 2026PDF ↗View work →

hexagon:2611.00002v1

math.NT — Number Theory

Rational limits in Markov–Euclid asymptotics

Contributed by Qiyue Tang

We construct an infinite reduced mutation sequence for which all three logarithmic Markov–Euclid ratios converge to 9/10. This disproves the irrationality conjecture of Zhichao Chen and Zelin Jia (Conjecture 6.12).

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

Nov 02, 2026PDF ↗View work →

hexagon:2611.00001v1

math.QA — Quantum Algebra

On the maximality conjecture for quantum permutation groups

Contributed by Teo Banica

A well-known conjecture, central in quantum permutation group theory, and going back to around 2006, states that $S_N\subset S_N^+$ is maximal. We revisit here this conjecture, and related questions, 20 years after, with 2026 knowledge and tools.

Primarily AI-generated textHuman understanding: some partsQuantum groupQuantum permutation

Nov 02, 2026PDF ↗View work →

hexagon:2610.00735v1

math.NT — Number Theory

On a Family of Counterexamples to Richard Guy's Mex Sequence Problem

Contributed by Shuta Iwai

We give a family of counterexamples to Richard Guy's problem E27 with initial terms of length five adding onto the recent example of length eight. Additionally, we prove that for length one, one always has a ultimately periodic sequence. Lastly we pose a problem regarding the notion of a zth mex sequence.

Primarily human-written textHuman understanding: all parts

Nov 02, 2026PDF ↗View work →

hexagon:2610.00734v1

math-ph — Mathematical Physics

Density coexistence for hard spheres with a long-range attractive pair interaction

Contributed by Qidong He

We prove low-temperature density coexistence for identical hard disks or hard spheres with a smooth, nonnegative, finite-range attractive Kac pair kernel. At every sufficiently large fixed inverse temperature and every sufficiently long finite interaction range, two translation-invariant Gibbs measures coexist, with densities near zero and maximal packing. The pressure is therefore nondifferentiable in chemical potential. The proof combines the contour construction of Lebowitz--Mazel--Presutti with a surface-pressure estimate for density bands near the two packing endpoints. A packing bound controls the fine density profile; centering the interaction makes its residual boundary contribution quadratic in the band width. Compatible near-packed configurations and conditional entropy then control the hard-core boundary contribution. These estimates allow the dense restricted ensemble to retain positional order and long-range correlations.

Primarily AI-generated textHuman understanding: no parts

Nov 02, 2026PDF ↗View work →

hexagon:2610.00733v1

math.QA — Quantum Algebra

Haagerup vertex operator algebras at central charge eight

Contributed by Cédric ARHANCET

Evans and Gannon showed that a positive vertex operator algebra of central charge eight whose representation category is the Drinfeld center $Z(\cal H_3)$ of the Haagerup fusion category has one of two character vectors, with six or nineteen currents. Call such an algebra, if strongly rational, a Haagerup algebra. We prove that a Haagerup algebra $U$ has six currents, that $U_1 \cong \mathfrak{sl}_2 \oplus \mathfrak{sl}_2$ embeds into $V_{E_6 \oplus A_2}$ in one of two explicit ways, with levels $(1,39)$ or $(3,13)$ , and we determine the lowest weight spaces of its modules and $U_2$ as $U_1$ -modules. For the levels $(3,13)$ , $U_2$ is one of four Galois conjugate subspaces, and the algebra it generates is unitary, $C_2$ -cofinite and isomorphic to the algebra constructed by Jiao; for the levels $(1,39)$ , $U$ contains the algebra announced by Riesen. The associated lattice of $U$ is that of the form $x^2+xy+10y^2$ , resp.\ $3x^2+3xy+4y^2$ , the two classes of the principal genus of discriminant $-39$ . Exchanging them in the decomposition of $U$ over its Heisenberg commutant gives a Haagerup algebra $U^\natural$ of the other levels, and $U \mapsto U^\natural$ is a bijection between the isomorphism classes of the two cases. Consequently, if either explicit algebra of Jiao or Riesen is positive and strongly rational with representation category braided equivalent to $Z(\cal H_3)$ , there are exactly two Haagerup algebras up to isomorphism, forming a single hyperbolic genus. The explicit algebras of Jiao and Riesen have rational forms. The proofs combine exact trace relations given by vector-valued modular forms, exact computations in a model of $V_{E_6 \oplus A_2}$ , and genera of vertex operator algebras.

A mix of human-written and AI-generated textHuman understanding: some partsDrinfeld centerHaagerup fusion categoryHeisenberg commutantgenus of vertex operator algebraslatticevector-valued modular formvertex operator algebra

Nov 02, 2026PDF ↗View work →

hexagon:2610.00732v1

math.FA — Functional Analysis

Wigner–Yanase–Dyson Metrics Have Monotone Curvature

Contributed by Suvrit Sra

Gibilisco and Isola conjectured that the scalar curvature of the Wigner–Yanase–Dyson metric with parameter $p$ on the invertible density matrices increases under mixing for all $p$ in some interval $(1,1+\varepsilon)$ ; the case $p\downarrow1$ is Petz's conjecture for the Kubo–Mori metric (resolved in a companion paper). We prove that for $p\in(1-\varepsilon,1+\varepsilon)$ , with $\varepsilon>0$ independent of the dimension, the scalar curvature is a concave function of the eigenvalues and hence increases under mixing. By Dittmann's formula it suffices to prove that one symmetric function $H_p$ of three positive variables is concave, which we do by showing that $-1/H_p$ is a Stieltjes transform along every line in the positive cone, uniformly in $p$ near $1$ . The value of $\varepsilon$ is not explicit.

A mix of human-written and AI-generated textHuman understanding: some partsKubo-Mori metricStieltjes transformWigner-Yanase-Dyson metricdivided differencesmajorizationscalar curvature

Nov 02, 2026PDF ↗View work →

hexagon:2610.00731v1

math.CA — Classical Analysis and ODEs

A sharp Brégman–Minc bound for permanents

Contributed by Suvrit Sra

We prove a sharp Brégman–Minc bound for permanents of nonnegative matrices that was conjectured by Samorodnitsky and Gurvits. Specifically, for $\phi(x)=\Gamma(1+1/x)^{-x}$ , with $\phi(0)=0$ , applied entrywise, we show that every nonnegative row-stochastic square matrix $A$ satisfies $\operatorname{per}\phi[A]\le1$ , which is the Brégman–Minc inequality when each row of $A$ is uniform on its support. The crux of our proof is a scalar inequality on the simplex, which we prove using a carefully chosen yet elementary integral representation. We note brief applications to the entropy of a random permutation and to sharp bounds for rectangular permanents and matchings.

A mix of human-written and AI-generated textHuman understanding: all partsBrégman-Minc inequalityGamma functionOrlicz normentropy boundperfect matchingspermanent

Nov 02, 2026PDF ↗View work →

hexagon:2610.00730v1

math.PR — Probability

The Macdonald $(q,t)$ -permanent II: Probability laws and their regions of validity

Contributed by Suvrit Sra

The Macdonald $(q,t)$ -permanent replaces the constant cycle weight of the Vere-Jones $\alpha$ -permanent by $(1-t^k)/(1-q^k)$ for a cycle of length $k$ . We determine which of the probability laws built on the $\alpha$ -permanent survive this deformation, and where. The scalar gamma-type law survives on the whole parameter square, but the matrix law, a compound Wishart matrix, is more fragile. We prove that it exists in every dimension exactly when $t\in\{0,q,q^2,\ldots\}$ , and in dimension two exactly when $t\le q$ . We conjecture that in each fixed dimension the matrix law exists exactly on the region that we show to be necessary, a $q$ -analogue of Gindikin's theorem.

A mix of human-written and AI-generated textHuman understanding: some partsCox processMacdonald permanentSchur measurealpha-permanentcomplete monotonicitycompound Wishart matrixinfinite divisibilityloop soupmatrix Laplace transform

Nov 02, 2026PDF ↗View work →

hexagon:2610.00729v1

math.CO — Combinatorics

The Macdonald $(q,t)$ -permanent I: Algebra and positivity

Contributed by Suvrit Sra

We introduce the Macdonald $(q,t)$ -permanent, a two-parameter cycle-weighted permanent that contains the usual permanent and determinant, as well as the $\alpha$ -permanent of Vere-Jones, as degenerate cases. We prove a MacMahon-type master theorem for its generating function, and determine when it induces a valid kernel on tuples of vectors. Nonnegativity of the $(q,t)$ -permanent itself on semidefinite matrices turns out to be subtler: for $t=q^\alpha$ nonnegativity holds exactly at the positive Wallach exponents; for a fixed $q$ we determine the region in rank two and for higher ranks under an additional condition, while for small $q$ positivity can even reach beyond the kernel region. Whether positivity forces $t\in\{0,q,q^2,\ldots\}$ remains an intriguing open problem.

A mix of human-written and AI-generated textHuman understanding: some partsMacMahon master theoremMacdonald permanentWallach setalpha-permanentimmanantpositive definite kerneltotal positivity

Nov 02, 2026PDF ↗View work →

hexagon:2610.00728v1

math.FA — Functional Analysis

Weak positivity of Schur forms under decomposable curvature

Contributed by Suvrit Sra

Griffiths's 1969 conjecture predicts positivity of Schur forms for Griffiths-positive vector bundles. Finski reduced its weak form to a sign question for the double mixed discriminant $\Phi_n(H)$ of a positive linear map. Du's rank-nine counterexample shows that $\Phi_n(H)\ge0$ fails in general. We prove $\Phi_n(H)\ge0$ for every decomposable map $H$ , a sum of a completely positive and a completely copositive map, using a quaternionic Gaussian determinant representation. Combined with Finski's incidence formula, this inequality gives weak nonnegativity of every Schur form under decomposable curvature, without splitting assumptions. Beyond the decomposable cone, nonnegativity of $\Phi_k(H_{V,U})$ on every square compression is equivalent to $\Phi_n(H+S)\ge0$ for every entanglement-breaking map $S$ . This class contains explicit indecomposable maps, but is nonconvex in every size $n\ge9$ . We prove the nonconvexity by expressing Du's map as an average of four members, and the obstruction persists when all compression inequalities are strict.

A mix of human-written and AI-generated textHuman understanding: some partsBreuer-Hall mapChern formGriffiths positivitySchur formdecomposable mapentanglement-breaking mapmixed discriminantpositive linear mapquantum permanent

Nov 02, 2026PDF ↗View work →

hexagon:2610.00727v1

math.RA — Rings and Algebras

A Koteljanskii inequality for permanents

Contributed by Suvrit Sra

We prove a permanental analogue of Koteljanskii's inequality. If $A$ is an inverse $M$ -matrix that becomes symmetric after a positive diagonal similarity, then $\mathrm{per}(A_{S\cup T})\,\mathrm{per}(A_{S\cap T})\ge\mathrm{per}(A_S)\,\mathrm{per}(A_T)$ for all $S,T\subseteq[n]$ , where $A_S$ is the principal submatrix indexed by $S$ . The proof expresses permanents as moments of a complex Gaussian vector and uses Ginibre's correlation inequality. Finally, an explicit counterexample shows that symmetry cannot be dropped.

A mix of human-written and AI-generated textHuman understanding: all partsFKG inequalityKoteljanskii inequalityM-matricescomplex Gaussianspermanents

Nov 02, 2026PDF ↗View work →

hexagon:2610.00726v1

math.FA — Functional Analysis

The $p$ -Bures–Wasserstein distance via $3\times3$ block matrices (with application to $p$ -Bures–Wasserstein barycenters)

Contributed by Suvrit Sra

We study the $p$ -Bures–Wasserstein distance $D_p(A,B)=(\mathrm{tr}\,A^p+\mathrm{tr}\,B^p-2\|A^{1/2}B^{1/2}\|_p^p)^{1/2}$ on positive semidefinite matrices; it equals the Bures–Wasserstein distance for $p=1$ , and the Hilbert–Schmidt distance for $p=2$ . We prove that $D_p$ is a metric for every $1\le p\le2$ , by proving a stronger 2014 conjecture of Lin and van den Driessche on $3\times3$ block matrices. Our main tool is a partition inequality for Schatten norms, proved by complex interpolation. We also characterize Fréchet means for $D_p$ by a fixed-point equation and prove geometric convergence of the associated iteration.

A mix of human-written and AI-generated textHuman understanding: all partsBures-Wasserstein distanceLin-van den Driessche conjectureSchatten normbarycenterscomplex interpolationpartition inequalitypositive semidefinite block matrices

Nov 02, 2026PDF ↗View work →

hexagon:2610.00725v1

math.CO — Combinatorics

On majorization inequalities for normalized Jack and Macdonald polynomials

Contributed by Suvrit Sra

We study the inequality $P_\lambda(x;q,t)/P_\lambda(1^n;q,t)\geq P_\mu(x;q,t)/P_\mu(1^n;q,t)$ for all $x\in\mathbb{R}_{>0}^n$ whenever the partition $\lambda$ majorizes $\mu$ ; Sra suggested it in 2015, and Chen, Khare and Sahi stated it as a conjecture in 2025. We prove the Jack case for every $n$ from Sun's positive Gelfand–Tsetlin integral and the Dixon–Anderson recursion. For Macdonald polynomials we prove the case $n=2$ , the covers $(d)\succeq(d-1,1)$ for every $n$ when $t\leq q$ , and, by exact certificates, the case $n=3$ with $|\lambda|\leq 8$ . The HCIZ mechanism behind the Jack proof has no direct finite- $q$ analogue: at two explicit pairs $(q,t)$ , no positive representation of the normalized ratio has a kernel multiplicative in $\lambda$ , and normalizing at the principal specialization $t^\delta$ instead fails the inequality.

A mix of human-written and AI-generated textHuman understanding: all partsDixon-Anderson integralHarish-Chandra-Itzykson-Zuber integralHeckman-Opdam hypergeometric functionJack polynomialsMacdonald polynomialsmajorization

Nov 02, 2026PDF ↗View work →

hexagon:2610.00724v1

math.CO — Combinatorics

The $q$ -Foulkes problem III: On Foulkes' conjecture with a graded inner factor

Contributed by Suvrit Sra

We show that surjectivity of the canonical map $\mathrm{Sym}^b(\mathrm{Sym}^aV)\to\mathrm{Sym}^a(\mathrm{Sym}^bV)$ survives grading of the inner factor. Consequently $h_b[H_a]-H_a[h_b]$ is Schur positive whenever the canonical map is surjective, where $H_a$ is the (modified) Hall--Littlewood polynomial; the same holds for (modified) Macdonald polynomials. We prove this surjectivity for $b\ge(a-1)^2$ , improving the known bound $a(a-1)$ . For Bergeron's $q$ -analog of Foulkes' conjecture that lets both factors be graded, we prove nonnegativity of every Schur coefficient for certain special cases. We also study the full conjecture under an expansion hypothesis on an explicit space of maps.

A mix of human-written and AI-generated textHuman understanding: some partsFoulkes conjectureFoulkes-Howe mapGaussian Newton expansionSchur positivitycoinvariant algebracurrent operatorplethysmq-Foulkes conjecture

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hexagon:2610.00723v1

math.CO — Combinatorics

The $q$ -Foulkes problem II: Schur positivity with high probability

Contributed by Suvrit Sra

Bergeron's $q$ -analog of Foulkes' conjecture asserts that $(H_b[H_a]-H_a[H_b])/(1-q)$ is Schur positive for $a\le b$ , where $H_n$ is the (modified) Hall--Littlewood polynomial. We view this conjecture probabilistically: on each irreducible representation of $S_{ab}$ , the two plethysms induce degree distributions, and positivity means that the first is stochastically smaller than the second. We prove that, for a random (Plancherel) irreducible representation and a degree sampled from its graded multiplicity, the corresponding coefficient is negative with probability at most $C\exp(-c(ab)^{1/3})$ , uniformly in $a\le b$ . Consequently, the $q$ -Foulkes conjecture holds after deleting a fraction at most $C\exp(-c(ab)^{1/3})$ of each of the two graded modules. Additionally, we show that exact conditional means and variances yield complete positivity for explicit width and height families.

A mix of human-written and AI-generated textHuman understanding: some partsMacdonald polynomialPlancherel measureSchur positivityplethysmq-Foulkes conjecturestochastic order

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hexagon:2610.00722v1

math.CO — Combinatorics

The $q$ -Foulkes problem I: A fusion inequality for Macdonald plethysms

Contributed by Suvrit Sra

We prove that the plethysm $H_m[\widetilde H_\mu]$ of a Macdonald polynomial by the Hall–Littlewood polynomial $H_m$ lies above the Macdonald polynomial $\widetilde H_{m\mu}$ obtained by fusing $m$ copies of $\widetilde H_\mu$ . More specifically, the quotient $(H_m[\widetilde H_\mu]-\widetilde H_{m\mu})/(1-q^m)$ is Schur positive with coefficients in $\mathbb N[q,t]$ , and it is the character of an explicit module that we call the fusion defect. For one-row shapes the inequality places both $q$ -Foulkes plethysms $H_b[H_a]$ and $H_a[H_b]$ above the same polynomial $H_{ab}$ , and comparing their two defects we obtain a distorted version of Bergeron's $q$ -analog of Foulkes' conjecture, in which the subtracted plethysm is shifted by $q^{a(a-1)\lfloor b/2\rfloor}$ .

A mix of human-written and AI-generated textHuman understanding: some partsMacdonald polynomialSchur positivityfusion productplethysmq-Foulkes conjecture

Nov 02, 2026PDF ↗View work →

hexagon:2610.00721v1

math.CA — Classical Analysis and ODEs

Sharp order-four sign regularity of a Jacobi theta kernel

Contributed by Suvrit Sra

We prove that the Hankel kernel $\Phi(\sqrt{x+y})$ , where $\Phi$ is the Jacobi theta kernel whose cosine transform is the Riemann $\Xi$ -function, is strictly reverse-regular through order four. The order is sharp: an interval enclosure of the fifth Hankel–Wronskian at $t=10^{-2}$ shows failure at order five. The third-order condition is Csordas's conjecture that $s'^2-ss''$ is strictly log-concave for $s(t)=\Phi(\sqrt t)$ . The proof reduces the kernel minors to Wronskian signs and establishes the signs by exact polynomial estimates for $t\ge1$ and interval arithmetic on $[0,1]$ . The fourth-order sign also yields three positive iterates of $s\mapsto s'^2-ss''$ , the triple Turán inequalities for the normalized Taylor coefficients of $\Xi$ , and quartic integral inequalities for $\Xi$ .

A mix of human-written and AI-generated textHuman understanding: some partsCsordas-VargaJacobi theta functionRiemann Xisign regularitytotal positivity

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hexagon:2610.00720v1

math.CA — Classical Analysis and ODEs

Monotonicity of Turán-ratios of symmetric polynomials

Contributed by Suvrit Sra

We study the Turán-ratio $S_{\lambda,i}(x)^2/(S_{\lambda,i-1}(x)S_{\lambda,i+1}(x))$ , where $S_{\lambda,i}(x):=s_\lambda(1^{[n-i]},x^{[i]})$ , and $s_\lambda$ is the Schur polynomial in $n$ variables (indexed by partition $\lambda$ ) with $i$ arguments equal to $x$ and $n-i$ of them equal to $1$ . Specifically, we prove that this Turán-ratio is strictly increasing for $x>1$ and $1\le i<n$ (unless all $n$ padded parts of $\lambda$ are equal, then it is identically one). For one-row shapes, our result answers a question of Ait-Haddou about complete homogeneous symmetric polynomials. For this case, we also offer a second proof through the zeros of Meixner polynomials that gives an explicit positive formula for the logarithmic derivative. We conclude with a Turán-ratio conjecture for Macdonald polynomials.

A mix of human-written and AI-generated textHuman understanding: all partsMeixner polynomialsSchur polynomialTuran ratiohomogeneous symmetric polynomialmonotonicity

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hexagon:2610.00719v1

math.OC — Optimization and Control

Lower bounds for the quantum permanent

Contributed by Suvrit Sra

Griffiths's 1969 conjecture on the positivity of Schur forms reduces to the positivity of the quantum permanent $\Phi_n$ on positive bistochastic maps. This conjecture was refuted by Du with a map for which $\Phi_9<0$ . Therefore, we ask: how negative can $\Phi_n$ be? We prove a lower bound $\Phi_n\ge-3n/(3n^2+20n+103)$ (for $n\ge 8$ ), and an asymptotically stronger bound $\Phi_n\ge-1/n+(3e^2-7-o(1))\log n/n^2$ . The key to our bounds is the orbital polynomial of the map, which turns $\Phi_n$ into a linear function of a distribution on partitions and positivity into linear constraints. We also construct explicit maps for $n=8, 9$ that improve on Du's example. Finally, if $d_*\in\{4,\ldots,8\}$ is the first dimension for which $\Phi_n<0$ , the minimum $\mu_n$ of $\Phi_n$ over positive bistochastic maps satisfies $-\mu_n=\Omega(n^{-d_*})$ ; we conjecture the matching order $-\mu_n=O(n^{-d_*})$ .

A mix of human-written and AI-generated textHuman understanding: some partsGriffiths positivitybistochasticlower boundspositive mapsquantum permanentsemidefinite programming

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hexagon:2610.00718v1

math.PR — Probability

Beyond Small Balls: A Determinant Inequality for Functions of Matrix Gaussian Series

Contributed by Suvrit Sra

We prove a functional extension of Gaussian operator-norm small-ball inequalities. Let $X=\sum_{i=1}^d g_iB_i$ , where $g\sim N(0,I_d)$ , the matrices $B_i\in\mathbb{R}^{d\times d}$ are symmetric, and $\sum_iB_i^2\preceq I_d$ . For every even log-concave $f\colon\mathbb{R}\to[0,\infty)$ , we obtain $\mathbb{E}\det f(X)\ge(\mathbb{E} f(\kappa G))^d$ at dilation $\kappa=13/5$ , where $G$ is standard Gaussian. The proof reduces each function to one small-ball estimate, obtained from matrix-weighted Poincaré inequalities, and controls the rest by averages over the spectrum. We give an equivalent entropy formulation. An explicit counterexample shows that no universal dilation below $\sqrt{\pi/2}$ can work; we conjecture that this value is optimal.

A mix of human-written and AI-generated textHuman understanding: all partsdeterminant inequalitylog-concave functionsmatrix Gaussian seriesrandom matricessmall-ball probabilities

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hexagon:2610.00717v1

math.FA — Functional Analysis

A Proof of Petz's Conjecture on the Scalar Curvature of the Kubo–Mori Metric

Contributed by Suvrit Sra

Petz (1994) conjectured that the scalar curvature of the Kubo–Mori metric on invertible density matrices increases as the state becomes more mixed. Dittmann (2000) reduced the conjecture to the concavity of an explicit symmetric function $h$ on $(0,\infty)^3$ . We prove that $h$ is strictly concave, and hence Petz's conjecture. The proof writes $h=-1/(8M)$ with $M$ positive and homogeneous of degree one, and its central idea is to show that $t\mapsto 1/M(X+tY)$ is a Stieltjes function for all $X,Y>0$ ; Cauchy–Schwarz and homogeneity then give concavity of $h$ on $(0,\infty)^3$ .

A mix of human-written and AI-generated textHuman understanding: all partsKubo-Mori metricMorozova-Chentsov kernelPetz conjectureStieltjes functionlogarithmic meanscalar curvaturestrict concavity

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hexagon:2610.00716v1

math.NT — Number Theory

A 7/8 zero-free half-plane for angular Hecke L-functions over the Eisenstein field

Contributed by Troy Winarski

We reconstruct the argument recorded in a frozen Lean development establishing nonvanishing of the unit-compatible angular Hecke $L$ -functions over $\mathbb{Q}(\sqrt{-3})$ in the strict half-plane $\Re(s)>7/8$ , apart from the genuine principal pole. The family includes every admissible integer angular order, all nonzero finite ideal moduli, primitive and imprimitive presentations, and real unitary norm twists. This strengthens the earlier $15/16$ result for the same angular family. The proof compares two estimates for a single normalized physical probe: a low bound with exponent $3/16+\omega$ and an approximation by a reciprocal Mellin signal with error exponent $\beta_n-11/16-\sigma$ , where $\beta_n$ is the supremum of the real parts of zeros within a finite angular cap. Crucially, the positive saving $\sigma$ is chosen before the target character. Mellin continuation converts these estimates into a strict improvement of the zero supremum. Induction on angular order, together with conjugation, establishes nonvanishing for the full family. The repaired public proof closure passed a clean compilation of 8,213 Lean modules and fresh native Lean kernel replay. An independent AI-assisted audit recorded five ACCEPT verdicts for the repaired package, following the identification and correction of a reproducibility defect in the original archive. We document the mathematical argument, formal verification evidence, and remaining limitations. This manuscript is an expository reconstruction, not independent human mathematical certification. We describe the formally verified proof as a *xenoproof* and the result provisionally as a *xenotheorem*, distinguishing machine-checkable correctness from established human mathematical understanding.

Primarily AI-generated textHuman understanding: some partsEisenstein integersHecke L-functionsLeananalytic number theoryangular Hecke charactersformal verificationxenoproofxenotheoremzero-free regions

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hexagon:2610.00715v1

math-ph — Mathematical Physics

Density functionals for the Pauli-Fierz Hamiltonian

Contributed by Mihaly A. Csirik, Andre Laestadius, Markus Penz, Erik I. Tellgren

We develop a density-functional theory for the Pauli-Fierz Hamiltonian of nonrelativistic quantum electrodynamics in the spirit of the convex-analytic formulation of Lieb. We consider finitely many electrons, subject to external scalar and vector potentials, coupled to the full continuum of massless transverse photons with an ultraviolet cutoff. The natural basic variables are the standard electron density and a combined current density, the sum of the paramagnetic current density and a field-induced current density generated by the quantized vector potential. We prove representability results for these density-current pairs and show that the mixed-state constrained-search functional attains its infimum and coincides with the Lieb functional obtained by convex conjugation. Since arbitrarily soft photons purify mixed states at a negligible energy cost without changing their density and combined current density, the pure-state Levy-Lieb functional equals the Lieb functional and is therefore convex, even though its infimum need not be attained. In addition, we establish the zero-coupling limit, which recovers the mixed-state Vignale-Rasolt functional of current-density-functional theory. Finally, we consider the long-wavelength (dipole) limit and show that the limiting functional can be written as a constrained search for the well-known length-gauge dipole Hamiltonian.

Primarily AI-generated textHuman understanding: all parts

Nov 02, 2026PDF ↗View work →

hexagon:2610.00714v1

math.NT — Number Theory

Every real primitive Dirichlet L-function has de Bruijn–Newman constant at most 9/32: a kernel-checked proof in Lean 4

Contributed by Peter W. Murphy, MD

Let χ be a real primitive Dirichlet character of conductor N ≥ 3 and parity k ∈ {0,1}. Let Λ(s,χ) = (N/π)^{(s+k)/2} Γ((s+k)/2) L(s,χ) be its completed L-function, and let H^χ_t(z) = ∫_0^∞ e^{tu²} Φ_χ(u) cos(zu) du be the de Bruijn–Newman heat flow of Λ(·,χ), normalised so that H^χ_0(z) = (1/8) Λ(1/2 + iz/2, χ). We give a proof, checked by the Lean 4 kernel, that for every such χ and every t ≥ 9/32 all zeros of H^χ_t are real. Equivalently, the generalised de Bruijn–Newman constant satisfies Λ_χ ≤ 9/32. The mathematics is not new, and we say exactly whose it is. De Bruijn's strip-contraction theorem (1950) gives Λ_χ ≤ D²/2 whenever the zeros of H^χ_0 lie in |Im z| ≤ D. Freire, González-Riquelme, Muñoz, Poblete and Salinas observed (arXiv:2610.27343, Remarks 3.1 and 3.4) that the zero-free half-plane Re s > 7/8 for Dirichlet L-functions asserted by OpenAI would give D = 3/4, and hence Λ_χ ≤ 9/32. What this paper adds is a complete formal proof of that composition. For conductors up to 400, FGMPS's unconditional bounds are stronger for 136 of the 242 characters; what is new is that 9/32, for every conductor, is a kernel-checked theorem. OpenAI's half-plane enters as their own kernel-checked Lean theorem. Every other step is proved in Lean on top of Mathlib: de Bruijn's theorem for a general class of kernels, the identification of the theta integral with Mathlib's completed L-function, and Gauss's sign theorem for real primitive characters. The final theorem depends only on the axioms propext, Classical.choice and Quot.sound. In local, unsandboxed replays five checkers accept it: Lean's kernel (run twice), nanoda, and the con-leche/con-ron pair. All five reject a deliberately unsound control. A sandboxed Comparator run against a separately written challenge also accepts it. That run was made by another agent session, and the auditor reproduced its solution export byte for byte. The result rests on OpenAI's Lean proof, whose accompanying manuscript is unrefereed. It is not progress on the Generalised Riemann Hypothesis, which is the statement Λ_χ ≤ 0. A short, separable section records two companion results for ζ that use no OpenAI code, Λ ≤ 225/512 and ψ(x) = x + O_ε(x^{31/32+ε}), both from Cureton and Thorner's half-plane Re s > 31/32. Code, verification records and archive: https://github.com/DrMurphyIsIn/real-dirichlet-dbn-lean (release v1.0.0); DOI 10.5281/zenodo.23840082.

Primarily AI-generated textHuman understanding: some partsDirichlet L-functionsGauss sumsLean 4Mathlibde Bruijn-Newman constantformal verification

Nov 02, 2026PDF ↗View work →

hexagon:2610.00713v1

math.CO — Combinatorics

Claw-free perfect graphs are chromatic-choosable.

Contributed by Narayanan Narayanan, Suchismita Mishra, Umesh Shankar

We prove that every claw-free perfect graph $G$ satisfies $\ch(G)=\chi(G)=\omega(G)$ . More strongly, if $S$ is a clique of simplicial vertices of $G$ and $k\ge\omega(G)$ , every proper precoloring of $S$ extends to a proper coloring of $G$ from arbitrary lists of size $k$ on $V(G)\setminus S$ . The proof has three coloring steps: a mixed-list theorem for cobipartite graphs, a precoloring-extension theorem for elementary graphs built on Galvin's kernel method and a homogeneous-pair exchange argument, and a polynomial method (Combinatorial Nullstellensatz) argument for graphs of interval type in which a Vandermonde factor is transferred across each incomplete pair. The three coloring steps are assembled along the structure theorems of Chv\'atal--Sbihi, Maffray--Reed and Chudnovsky--Seymour, using double clique cutsets for composition. As a consequence, every perfect line graph is chromatic-choosable, recovering the theorem of Peterson and Woodall. Our precoloring extension theorem also resolves a conjecture posed by Chudnovsky and Seymour.

A mix of human-written and AI-generated textHuman understanding: all partsClaw-free perfect graphs.Graph coloringList Coloring Conjecture

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hexagon:2610.00711v1

math.NT — Number Theory

An Improved Subexponential Bound for Deterministic Integer Factorization

Contributed by Joseph Shunia

We prove that the complete prime factorization of an $n$ -bit integer can be computed deterministically in time $2^{O(n/\sqrt{\log n})}$ and polynomial space. This establishes the bound conjectured by Rudich and Rousseau, sharpening their qualitative $N^{o(1)}$ result. The proof combines OpenAI's quantitative Boolean tensor-contraction theorem with the linear-size multiplication encoding of Akshima et al. The encoding permits exact counting of divisors with prescribed binary prefixes without loss in the exponent. The least prime factor is then recovered by successive prefix queries, and iteration yields the complete factorization within the same asymptotic bound.

Primarily AI-generated textHuman understanding: all partsBoolean tensor networksdeterministic algorithmsexact countinginteger factorizationsubexponential time

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hexagon:2610.00709v1

math.PR — Probability

Upper bounds for the Chvátal–Sankoff constants $\gamma_k$ , $k\ge3$

Contributed by David Niedbala Giraudin

Lueker (J. ACM 56(3), 2009) constructed a family of finite-state machines $\mathcal{M}_h$ whose associated transfer matrices yield upper bounds on the Chvátal–Sankoff constants $\gamma_k$ , and proved (his Theorem 3.26) that these bounds converge to $\gamma_k$ for every alphabet size $k$ . He published values only for $k=2$ . For $k\ge3$ the best upper bounds we were able to find in the literature in September 2026 were still those of Dančík's 1994 thesis: subsequent work generalising Lueker has generalised his Section 2, the lower bound. We implement $\mathcal{M}_h$ for arbitrary $k$ . One ingredient has no binary analogue — the generating function of a truncation class when both sides of a minimal match pair are truncated — and we derive it. We then give a reduction by relative forms under which the transition multiplicities of the transfer matrix are falling factorials in $k$ ; one alphabet-free construction consequently determines the exact matrix for every $k$ . We obtain improved upper bounds for $k=3,\dots,15$ , each supported by a Collatz–Wielandt certificate verified in exact rational arithmetic, among them $\gamma_5\le0.645033$ . A note added on 31 October 2026 compares these values with those of a repository made public by L. Jack on 25 October 2026.

Primarily AI-generated textHuman understanding: no partsChvátal–Sankoff constantsCollatz–Wielandt certificateslongest common subsequencetransfer matrices

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hexagon:2610.00708v1

math.NT — Number Theory

A closed-form bound for linear forms in three $p$ -adic logarithms of rational numbers

Contributed by David Niedbala Giraudin

We deduce from the $p$ -adic kit for three logarithms of the companion note hexagon:2610.00706 a fully explicit bound in closed form. If $\gamma_1,\gamma_2,\gamma_3$ are multiplicatively independent rationals, congruent to $1$ modulo $p$ (modulo $4$ if $p=2$ ), of heights at most $a_j\log p$ with $a_j\ge1$ , and if $|b_j|\le B$ , then $v_p(\gamma_1^{b_1}\gamma_2^{b_2}\gamma_3^{b_3}-1)\le a_1a_2a_3\,\mathcal{B}^2\max\{27\,711,\ C_2(p)\max_j a_j\}$ , where $\mathcal{B}=\max\{\log B/\log p,\,10\}$ and $C_2(p)=11\,107\,\frac{p}{p-1}\bigl(1+\frac{0.31}{\log p}\bigr)^2$ , as soon as $\gamma_1^{b_1}\gamma_2^{b_2}\gamma_3^{b_3}\ne1$ . By a change of basis in the multiplicative group, the result applies to arbitrary rationals prime to $p$ . On the examples of that note, the bound is $42$ to $956$ times smaller than that of Yu's explicit theorem, and stays within a factor between $1.2$ and $2.5$ of the numerical optimisation of the parameters of the kit.

Primarily AI-generated textHuman understanding: no partsYu's theoremexplicit boundsinterpolation determinantslinear forms in p-adic logarithms

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hexagon:2610.00707v1

math.NT — Number Theory

The exponent of $p$ in $x^{p-1}-1$ : Yamada's constant 283 lowered to 69

Contributed by David Niedbala Giraudin

Yamada (J. Number Theory 130, 2010) deduced from the method of interpolation determinants of Bugeaud and Laurent the bound $v_p(x^{p-1}-1)\le 283\,(p-1)\log y\,\log(xy)/(\log p)^2+4$ , for multiplicatively independent integers $x,y$ coprime to $p$ . We replace 283 by 69. The new ingredient is an elementary bound, by rearrangement, on the spread of the exponents that occur in the Liouville inequality: it at least halves the height term of Yamada's criterion, involves no congruence class, and allows the parameters to be re-optimised. The proof is complete up to the lemmas of Bugeaud–Laurent (zero lemma, analytic upper bound) and of Laurent–Mignotte–Nesterenko (bound for the polynomial), which are used as they stand. A self-contained verifier checks the numerical inequalities.

Primarily AI-generated textHuman understanding: no partsFermat quotientsYamada's boundinterpolation determinantslinear forms in p-adic logarithms

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hexagon:2610.00706v1

math.NT — Number Theory

A kit for linear forms in three $p$ -adic logarithms

Contributed by David Niedbala Giraudin

We transpose to the $p$ -adic case the kit of Mignotte and Voutier for linear forms in three logarithms. The new tool is a lower bound for the $p$ -adic valuation of interpolation determinants with no factorial loss: it is obtained by expanding the powers $\theta^{\ell z}$ as binomial series in $\theta-1$ , and then transporting an order of vanishing that we compute optimally for generic points, by means of the initial forms of the space of exponential polynomials involved. It holds for every prime $p$ . Combined with a rearrangement bound for the spread of the exponents and with Gouillon's zero lemma applied within a Teichmüller class, it gives a criterion of the form of criterion (2.8) of Mignotte–Voutier, in which $\log\rho$ is replaced by $\log p$ and the height term contains no analytic contribution. For two logarithms, in $\mathbb{Q}_p$ with $p$ odd, it improves Lemma 8 of Bugeaud–Laurent. A change of basis in the multiplicative group reduces to the case of principal units: the factor $g=p-1$ leaves the volumes and moves into the heights. On examples, with exponents up to $10^{10}$ or $10^{30}$ , the complete bounds (degenerate cases included) are $154$ to $667$ times smaller than those of Yu's explicit theorem for $p\in\{5,13\}$ , $608$ to $1980$ times for $p\in\{7,11\}$ (where the explicit form of Yu goes through $\mathbb{Q}(i)$ ), and $73$ to $105$ times for $p=101$ .

Primarily AI-generated textHuman understanding: no partsBaker's methodYu's theoreminterpolation determinantslinear forms in p-adic logarithms

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hexagon:2610.00705v1

math.MP — Mathematical Physics

Riordan lattice paths counted by area

Contributed by Ilmar Gahramanov

We study Riordan paths enumerated by the area between the path and the axis. We show that the generating function satisfies a $q$ -Riccati equation and can be written in a closed form as a ratio of basic hypergeometric series. The auxiliary series admits an algebraic representation as the motivic generating series of a symmetric two-node quiver. We obtain explicit formulas for the coefficients, the exponential asymptotics of the number of paths of given area, and a linear recurrence whose coefficients are signed counts of partitions into distinct parts. For a random path of area $n$ we obtain a joint Gaussian limit law for the numbers of returns, horizontal steps and up steps. The height is of order $\sqrt{\log n}$ , and its distribution concentrates on two adjacent integers determined explicitly by $n$ .

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

Nov 02, 2026PDF ↗View work →

hexagon:2610.00704v1

math.NT — Number Theory

An optimal multiplicity estimate for interpolation determinants in three logarithms

Contributed by David Niedbala Giraudin

In the kit of Mignotte and Voutier for linear forms in three logarithms, the order of vanishing at the origin of the interpolation determinant is bounded below by Waldschmidt's general multiplicity lemma; the authors indicate that this estimate should be improvable. We give a lower bound for this order which is optimal for generic points. The functions involved span a space whose initial forms are described by a uniqueness property for a linear differential equation with constant coefficients. As a consequence, the left-hand side of their criterion (2.8) can be taken equal to $\frac{(2K+1)(L-1)}{3}\log\rho$ , with main term $\frac{2KL}{3}\log\rho$ instead of $\frac{KL}{2}\log\rho$ . On the two examples of their paper, with their public code modified in one line and the conditions of the zero lemma checked, the bounds given by the criterion go from $17.94\cdot10^6$ to $4.79\cdot10^6$ and from $28.85\cdot10^6$ to $7.00\cdot10^6$ . The same estimate is the multiplicity input of our kit for three $p$ -adic logarithms.

Primarily AI-generated textHuman understanding: no partsinterpolation determinantslinear forms in logarithmsmultiplicity estimateszero lemma

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hexagon:2610.00703v1

cs.CC — Computational Complexity

The Esperanza Algorithm for Maximum Independent Set

Contributed by Frank Vega

The maximum independent set problem asks for the largest set of pairwise non-adjacent vertices in an undirected graph. It is NP-hard to approximate within $n^{1-\varepsilon}$ for every $\varepsilon>0$ , and under the Unique Games Conjecture it is hard to approximate within $O(\Delta/\log^2\Delta)$ on graphs of maximum degree $\Delta$ ; the Khot--Regev form of the conjecture, for which a proof has been reported but not yet peer reviewed, also rules out a $(2-\varepsilon)$ -approximation of Minimum Vertex Cover. We present version 0.1.6 of \textsc{Esperanza}, which takes the better of a dynamic minimum-degree (Caro--Wei) greedy set and the complement of the \textsc{Salvador} vertex cover, and improves it by three budgeted local searches: repair-and-grow restarts at the cover vertices and at a maximum-degree vertex, chained local restarts realising $(k,k+1)$ -improvements, and an iterated $(1,2)$ -swap search. We prove that it runs in $O((n+m)\,\alpha_{\mathrm A}(n))$ expected time for fixed budgets, with $\alpha_{\mathrm A}$ the inverse Ackermann function. We prove that the output is a maximal independent set, that its complementary vertex cover has at most $2\tau-r$ vertices, where $\tau$ is the minimum cover size and $r$ the number of components with an edge, and that the ratio is at most $(\Delta+2)/3$ on graphs of maximum degree $\Delta$ . We prove the ratio $2\sqrt n$ on every graph with $\Delta\le\sqrt n$ and on three further classes, and state it for all graphs as a conjecture, whose proof would imply $\mathrm{P}=\mathrm{NP}$ . We also state the conjecture that the complementary cover has at most $2\tau-|M|$ vertices for the NetworkX minimum maximal matching $M$ ; a proof would give a $3/2$ -approximation for Minimum Vertex Cover and refute the Unique Games Conjecture unless $\mathrm{P}=\mathrm{NP}$ . In reproducible experiments the returned set is optimal on all $30\,000$ graphs of a suite certified by an exact integer program; on $40$ Khot--Regev YES instances with $640$ to $2\,560$ vertices the conjectured bound is certified on $38$ and open on $2$ ; and on $31$ bounded-degree graphs the certified ratio is at most $1.0769$ on the families with a planted independent set.

Primarily AI-generated textHuman understanding: all partsApproximation AlgorithmBounded-degree GraphsLinear TimeMaximum Independent SetP versus NPUnique Games ConjectureVertex Coverlocal search

Nov 02, 2026PDF ↗View work →

hexagon:2610.00702v1

math.NT — Number Theory

Robin's Inequality at Colossally Abundant Numbers and Nicolas' Inequality at Their Largest Prime Factor

Contributed by Frank Vega

Robin's criterion states that the Riemann Hypothesis holds if and only if $\sigma(n) < e^{\gamma} \cdot n \cdot \log\log n$ for every $n > 5040$ , and Nicolas' criterion states that it holds if and only if $c(q) = \log(q\#/\varphi(q\#)) - \gamma - \log\log\theta(q) > 0$ for every prime $q$ , where $q\#$ is the primorial of $q$ and $\theta$ is the Chebyshev function. Let $N$ be a colossally abundant number, let $\xi(N)$ be the real number associated with $N$ by Nicolas, and let $q$ be the largest prime not exceeding $\xi(N)$ . Writing $\Delta(N) = \log(\sigma(N)/N) - \gamma - \log\log\log N$ , we prove without any hypothesis that, whenever $\log q \geq 31$ , $1.353/(\sqrt{q} \log^{2} q) \leq \Delta(N) - c(q) + 2\sqrt{2}/(\sqrt{q} \log q) \leq 3.970/(\sqrt{q} \log^{2} q)$ . Thus Robin's inequality at $N$ and Nicolas' inequality at $q$ differ by $2\sqrt{2}/(\sqrt{q} \log q)$ up to an explicit error of smaller order. As consequences, every colossally abundant counterexample to Robin's inequality yields a prime $q$ with $c(q) > 2.70/(\sqrt{q} \log q)$ ; conversely, every prime $q$ with $\log q \geq 31$ and $c(q) > 2\sqrt{2}(1 - 0.4787/\log q)/(\sqrt{q} \log q)$ yields a colossally abundant counterexample, so that Nicolas' oscillation theorem implies Robin's theorem on colossally abundant counterexamples; and under the Riemann Hypothesis every colossally abundant number with $\log q \geq 31$ satisfies $\Delta(N) < -0.654/(\sqrt{q} \log q)$ , in accordance with the constant $2(\sqrt{2}-1)$ of Ramanujan's bound. For superabundant counterexamples, using the exponent bound of Nazardonyavi and Yakubovich, which gives $\log n \geq \psi(p_{k})$ for the largest prime factor $p_{k}$ , we prove $c(p_{k}) > 0.9991/(\sqrt{p_{k}} \log p_{k})$ , and we show that the least colossally abundant number not smaller than the least counterexample $n$ is itself a counterexample $N$ with $\log N - \log\xi(N) \leq \log n$ .

Primarily AI-generated textHuman understanding: all partsChebyshev functionColossally abundant numbersNicolas' inequalityRiemann HypothesisRobin's inequalitySuperabundant numbersprimorial

Nov 02, 2026PDF ↗View work →