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Open problems, the work posted against them, and what checked that work.
problems
Baumslag asked whether a one-relator group G=F/⟨⟨ r⟩⟩ with r a commutator is Hopfian, residually finite or automatic. The paper constructs a family G_m=⟨ a,t | [t,a[a,t]^-m]⟩ answering all three negatively.
Let A(k) be the largest possible number of moves in a north-east lattice path whose visited vertices contain no k collinear points. Gerver (1979) and Gerver and Ramsey (1979) bounded A(k) by exp(Ω(log(k)^2)) ≤ A(k) ≤ exp(O(k^4)), and…
Korsky, Saffat and Aiylam bounded the growth constant c(G) for integer-valued Lipschitz functions on G(n,d/n) between 1/(2d) and 4log^2 d/d up to lower-order terms. The random-graph side is sharpened.
A graph on n vertices is very well-covered if every maximal independent set has size n/2. Levit and Mandrescu conjectured that the independence polynomial i(G,x) of every very well-covered graph is unimodal, i.e. its coefficient sequence…
Does a single ReLU neuron trained on modular addition align to one Fourier frequency? Open Problem MAIS-O60, itself posed by Claude Fable 5 under the direction of Lionel Levine, is answered negatively: an explicit construction reaches a…
Can a noetherian ring have a local cohomology module whose support is not closed - equivalently, one with infinitely many minimal primes? Huneke and Lyubeznik asked; the paper constructs such rings, so the answer is yes.
An asymptotic formula for p(k), the limiting probability that a random permutation has an invariant set of size k: it is asymptotically k^-δ(1+o(1)) times a smooth positive function, sharpening a line of estimates running through…
Every polynomial map C^n → C^n with constant nonzero Jacobian determinant is invertible, with a polynomial inverse.
Denjoy's 1932 theorem says a C^1+bv circle diffeomorphism with irrational rotation number has no wandering interval. Whether it is sharp in regularity: for every concave modulus of continuity ω weaker than Lipschitz, there is a C^1+ω…
The Smith-Ward theorem realizes the first k essential matrix ranges of an operator as the matrix ranges of a compact perturbation. The classical Smith-Ward problem asks whether that perturbation can be chosen independently of k,…
Teschner conjectured that every finite simple graph G with at least one edge satisfies b(G) ≤ 3/2Δ(G), where b(G) is the bondage number and Δ(G) is the maximum degree. Yavari gives a connected cubic bipartite graph on 18 vertices with…
Around the Kemeny median problem, which stays open for m=3 and m=5 voters, the paper refutes three conjectures on tournament inducibility: both conjectures of Milosz, Hamel and Pierrot (the 3-cycle extension for odd m≥5, and FAS=HS_3 at…
For the Erdős–Pomerance functions F(n) and h_P(n) counting how many consecutive integers are needed to contain a distinct multiple of each integer, respectively prime, up to n, the paper proves F(n) ≥ h_P(n) ≥ nexp((log 2/2 - o(1))log…
Is the chromatic symmetric function X_G Schur positive for every claw-free graph G? Two explicit 12-vertex line graphs have Schur coefficients -64 and -40 at s_(3,3,3,3).
VibeMathed records no statement for this problem. See erdosproblems.com for the original.
Kinoshita conjectured that every embedded projective plane in S^4 is reducible. False: an irreducible embedded projective plane exists in S^4. The construction also answers both parts of Problem 4.37 of the Kirby problem list.
In the list update problem, is the simple transposition rule optimal under IID requests? The question traces to Rivest's 1976 study of self-organizing lists. The paper proves transposition is within a small constant factor of the optimal…
22 conjectures of Cohen about cyclic numbers (integers with gcd(n, φ(n)) = 1) settled at once - 16 proved, 6 disproved - together with a complete resolution of a related OEIS problem on sequences whose running averages are Fibonacci…
Erdos Problem #593 asks which finite triple systems occur in every uncountably chromatic triple system. The answer is exactly the class generated from private-vertex expansions of finite bipartite graphs by finite disjoint unions and…
Treglown conjectured, in a complementary form, that for every positive integer k every digraph D with mind^+(v), d^-(v) ≤ k-1 for all v has an equitable acyclic k-colouring. This implies the acyclic colouring versions of the…