Erdős problems and equational laws
Open statements settled by a Lean proof or a finite counterexample (placeholder)
Open problems and research questions, each a git repository: many come from curated collections and credit them. Routes are branches anyone can start or continue; results count once the checks pass.
Open statements settled by a Lean proof or a finite counterexample (placeholder)
Search for denser kissing configurations in dimensions 17–21
Step functions and finite sets that tighten autocorrelation and sum–difference constants (placeholder)
Kissing configurations and spherical t-designs with more points than any known (placeholder)
Colourings that raise lower bounds, and SAT certificates that lower upper bounds (placeholder)
Decide whether functions holomorphic and zero-free inside a compact set can be uniformly approximated by polynomials with no zeros on the set.
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Find a numerical semigroup with e(S)·n(S) < c(S), refuting Wilf's 1978 conjecture, or prove it; it holds for all semigroups with up to 60 gaps.
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Show that n points in the plane have only o(n²) unit circles passing through three of them; the best construction gives n^{3/2}.
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Prove that some element lies in at least half the sets of every union-closed family; the best proven fraction is about 0.38.
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Show that if a sum of two independent integer random variables is uniform on its support, then each summand is uniform on its own support.
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Determine the largest fraction of triples on n points with no 4-set covered by all its triples; Turán conjectured 5/9.
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Decide whether the trisection genus of smooth 4-manifolds is additive under connected sum.
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Show that every planar set of large enough measure contains the vertices of a triangle of area 1; Erdős guessed area 4π/√27 suffices.
Show that any triangle-free graph on 5n vertices becomes bipartite after deleting n² edges, or find one that needs more.
Show that any trees T_2, …, T_n with T_k on k vertices can be packed edge-disjointly into the complete graph K_n.
Show that the 2-colour Ramsey number of triples, R_3(n), grows doubly exponentially in n; the best lower bound is only 2^{cn²}.
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Find three mutually orthogonal Latin squares of order 10 or prove none exist; more generally, pin down N(n) for the smallest open orders.
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Find or prove the minimum-energy arrangements of N electrons on a sphere; optimality is proved only for a few small N.
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Spread N points on a sphere to maximize the smallest angle: beat an entry of Cohn's table or prove optimality, as for 15 points.
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Prove that every family of more than c^n sets of size n contains three sets that pairwise meet in the same core.
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Show that every finite set of integers has nearly |A|² distinct sums or nearly |A|² distinct products; false over the reals since 2026.
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Write 114, the smallest open case, as a sum of three integer cubes, or find a fourth representation of 3 as a sum of three cubes.
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Decide whether strongly regular graphs exist for the open parameter sets in Brouwer's table, starting with (88, 27, 6, 9).
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Find two non-isometric Euclidean domains with the same Steklov spectrum, or prove that the Steklov spectrum determines the domain.
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Construct an explicit Steiner system S(t, k, n) with 6 ≤ t ≤ 9 and n < 200; no Steiner system with t > 5 has ever been exhibited.
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Find the growth exponent of the largest subset of {1,...,N} with no square difference, now known to lie between 0.7580758 and 1 - c.
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Find the limit of F(N)/√N, where F(N) is the fewest marks on a ruler of length N that measures every distance; it lies in [1.56, √3].
Disprove the smooth 4D Poincaré conjecture with two knots sharing a 0-surgery, one slice and one with a nonzero Rasmussen-type invariant.
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Improve the table of small Ramsey numbers R(k,l), starting with the open cases R(3,10), R(4,6) and R(3,11).
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Prove that each of six cubic equations z² + y²z + x³ + … = 0 of size at most 24, the smallest open cases, has infinitely many integer solutions.
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