Math, Inc. reports Lean formalizations of sphere-packing optimality for the E₈ lattice in dimension eight and the Leech lattice in dimension 24, with uniqueness among periodic packings in dimension 24. The human maintainers report checking definitions, axiom dependencies and the supplied code.
The manuscript reports arbitrarily large finite simple graphs with independence number at most two and chromatic number greater than their largest clique-minor order. It also claims violation of the ordinary fractional-coloring weakening.
Ellenberg, Libedinsky, Plaza, Simental and Williamson prove that for n=2^m, dyadically well-distributed permutations form a Bruhat interval isomorphic to a hypercube of dimension m·2^(m−1). This has order n log n, within a constant factor of the maximum.
OpenAI reports that every positive-integer set with divergent reciprocal sum contains arithmetic progressions of every finite length, through fixed-length bounds r_k(N)≤C_k N exp(−c_k(log N)^ε_k).
OpenAI reports a bipartite graph with 35 vertices and 66 edges whose homomorphism density in a finite simple host is below the predicted edge-density bound; it also reports failure of the associated forcing assertion.
OpenAI reports that every nonempty finite oriented graph has a vertex with at least as many vertices at directed distance exactly two as at directed distance one.
The authors report configurations packing 11 and 12 unit regular hexagons inside regular hexagons of approximate side lengths 3.931 and 3.942, respectively.
Patterns, colorings, and discrete constructions, including Ramsey theory, cap sets, and geometric combinatorics.
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