Convex, discrete and metric geometry

Convex bodies, distances, packings, coverings and discrete geometric configurations.

Individual problems 121

Curated contributions 100

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Contribution counts by ratings

AI involvement:
AI-centered34AI-led60AI-autonomous6
Importance:
Modest9Notable50Major41
Technical verification:
Reported19Partial13Formal68
Human understanding:
Few55Partial6Full39
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Every two-coloring of the plane misses at most one triangle, which is equilateral

In every arbitrary two-coloring of the Euclidean plane, each non-equilateral three-point set, including three distinct collinear points, has a monochromatic congruent copy. At most one equilateral side length can be missed, and an alternating-strip coloring shows that one exception can occur.

AI involvementAI-autonomous
ImportanceNotable
Technical verificationFormal (Lean)
Human understandingFew

AI-led Lean proof settles a seven-vertex unit-distance case

For every simple graph G on seven vertices, either G or its complement has an injective unit-distance representation in Euclidean R³, where every edge has length one and nonedges are unconstrained. This proves the d=3 case of Frankl–Kupavskii–Swanepoel Problem 2; their general 2d+1-vertex question remains open. Combining with the published lower bound gives f_D(7)=3, although the lower bound is outside the formal target.

AI involvementAI-led
ImportanceModest
Human understandingFew

AI-built Lean program triangulates simple polygons in linear time

For every closed simple polygon with n vertices, including collinear vertices and equal heights, an explicit exact-real-RAM program returns a conforming triangulation with n−2 triangles in at most C(n+1) steps and natural words bounded by K(n+1). It is a variant of Chazelle’s algorithm that completes the visibility map directly below n=2³⁰+2.

AI involvementAI-led
ImportanceNotable
Human understandingFew

AI-derived bounds for Mazur’s greedy drawing construction

For a well-formed Mazur edge, cycle, series and join scheme with n≥2 vertices and j nontrivial joins, the span satisfies T+1≤2^j(n−2j), with equality at (n,j)=(2,0) or 2j+3≤n. Its worst case is T=2^(n/2)−1 for even n and T=3·2^((n−3)/2)−1 for odd n. Companion theorems give interior dart mass ≤aₛbₛT, Dirichlet row norm ≤2(n−1)²T and |det M|≤(2(n−1)²T)^n, bound the candidate products T²|det M| and T³|det M|, and prove z=adj(M)u with Mz=Δu and boundary zₛ=Δhₛ(T−hₛ) when hₛ≤T, where Δ=det M.

AI involvementAI-led
ImportanceModest
Human understandingFew

Two Möbius groups suffice: Euclidean Ramsey sets on spheres of every dimension, after the tensor classification

Will Strinz

Strinz reports that every finite set of distinct points on a circle is Euclidean Ramsey when all but at most three points have coordinates algebraic over Q. The circle’s center and radius may be arbitrary real numbers.

Revisiting Separators in String Graphs, Region Intersection Graphs, and Induced-Minor-Free Graphs

James Davies, Paweł Rzążewski, Jack Spalding-Jamieson, Bartosz Walczak

The AI-origin improvement in Appendix B gives non-expansive line embeddings with O(log h) average distortion for the stated vertex-weighted metrics of connected graphs excluding the one-subdivision of K_h as an induced minor. The paper derives balanced separators of size O(h log h √m) for the corresponding m-edge graphs.

AI involvementAI-centered
ImportanceNotable
Technical verificationFormal (Lean)
Human understandingFull

ChatGPT-led proof establishes optimality and uniqueness of Romik’s ambidextrous sofa

Every compact connected planar set that can be moved continuously through both a right-turning and left-turning unit-width hallway from the same starting orientation has area at most M=1+4Y²+arctan(Y), where Y>0 solves 4Y³+3Y=1. Equality holds exactly for rotated and translated copies of Romik’s sofa, and the sofa attains M.

AI involvementAI-led
ImportanceMajor
Technical verificationFormal (Lean + comparator)
Human understandingFew

AI agents prove six concyclic points meet a Euclidean Ramsey tensor criterion

Every set of six distinct points on a circle satisfies the FieldCriterion tensor condition of the OpenAI Euclidean Ramsey classification. More generally, every spherical finite set of at most m+4 points, where m is its affine-span dimension, satisfies that criterion in its own coordinate field; every spherical set with algebraic coordinates also satisfies it.

AI involvementAI-led
ImportanceNotable
Technical verificationFormal (Lean)
Human understandingFew

OpenAI reports a tensor classification of finite Euclidean Ramsey sets

A finite Euclidean configuration is Ramsey for monochromatic congruent copies at its original scale exactly when its coordinate field admits the paper’s rational-tensor matrix satisfying the pointwise evaluation identities and identity-matrix product identities; the criterion covers every affine dimension.

AI involvementAI-led
ImportanceMajor
Technical verificationFormal (Lean 4)
Human understandingFew

OpenAI reports a doubling Hilbert set with no finite-dimensional bi-Lipschitz embedding

A subset of real Hilbert space has doubling constant at most 76,800 yet admits no bi-Lipschitz embedding into any finite-dimensional Euclidean space at any finite distortion. Moreover, every infinite-dimensional real Banach space contains a compact doubling subset with the analogous obstruction and a universal doubling bound.

AI involvementAI-led
ImportanceMajor
Technical verificationFormal (Lean 4)
Human understandingFew

OpenAI reports the Euclidean Steinitz–Bergström bound

Every prescribed-order finite sequence of vectors in the Euclidean unit ball of R^d has one choice of signs whose every signed prefix has norm at most C sqrt(d), with C independent of sequence length. Consequently every indexed zero-sum family admits an ordering with every unsigned prefix bounded by C sqrt(d).

AI involvementAI-led
ImportanceMajor
Technical verificationFormal (Lean 4)
Human understandingFew

Optimal packings of one to seven unit squares in a disk

The-Anh Vu-Le

For five, six and seven freely rotated, interior-disjoint unit squares in a closed disk, the project reports exact least radii √(5/2), √q* and √13/2, respectively, where q* is its specified quartic root. It classifies all optimal packings up to rotation and relabelling: the five- and six-square optima are unique, while seven squares admit a three-parameter family.

AI involvementAI-led
ImportanceNotable
Human understandingFew

Uniqueness of four-body convex central configurations for all masses

Tejasvi Singh Tomar

For four positive masses in the planar Newtonian problem, each cyclic order has exactly one strictly convex central configuration up to similarity. The v2 theorem also gives Q≥K/4 at every convex configuration, nondegenerate local minima and analytic dependence.

Triangular minimality for planar Coulomb renormalized energy

OpenAI

For the manuscript’s unit-background planar Coulomb renormalized-energy class and admissible square-cutoff families, every admissible field has energy at least that of the density-one triangular lattice. A prior equivalence then identifies the linear term of optimal spherical logarithmic energy.

AI involvementAI-led
ImportanceMajor
Technical verificationPartial
Human understandingFew

Translative covering densities of order n log n

OpenAI

For every sufficiently large dimension n, an OpenAI manuscript constructs a centrally symmetric convex body whose unrestricted translative covering density exceeds c n log n for an absolute c>0. With Rogers’ O(n log n) upper bound, this fixes the worst-case unrestricted order and rules out a universal O(n) bound.

AI involvementAI-led
ImportanceMajor
Technical verificationReported
Human understandingFew

A cyclic non-Ramsey heptagon

Dömötör Pálvölgyi

For every transcendental radius r>2, a seven-point set on a circle of radius r, including r=π, has a finite coloring of Euclidean space with no monochromatic congruent copy in any dimension.

AI involvementAI-autonomous
ImportanceMajor
Technical verificationReported
Human understandingFew

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