Open Conjecture Board

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Confirmed proofs, counterexamples, and prior work that close Board entries.

ConjectureResolutionResolverDateEvidence
The signature of a connected line graph is at most 1 (Akbari, Elphick, Kumar, Pragada, Tang, Discrete Math. 349 (2026) 114953, Conjecture 4.12). counterexample Luke Francis and Trevor Uptain arXiv link pending
The Dinitz-Garg-Goemans conjecture on unsplittable flows (open roughly 30 years). counterexample Dmitry Rybin evidence
For every nontrivial connected graph, the minimum maximal matching number is at most the harmonic index (TxGraffiti conjecture, 2023). counterexample Bıyıkoğlu; smallest cases identified by Gupta evidence
Brouwer's conjecture: the sum of the t largest Laplacian eigenvalues of any graph is at most e(G) + t(t+1)/2. proof Kothari and Tudose evidence
Every graph satisfies 2n+(G) ≤ n−(G)(n−(G)+1) (Akbari, Elphick, Kumar, Pragada, Tang, quadratic inertia conjecture). counterexample H. Chen and J. Li evidence