The coarse connectivity witness conjecture
The coarse connectivity witness conjecture
Let . A graph is -quasi-isometric to a graph of tree-width at most in the usual coarse sense, and connected sets are at least apart when every pair of vertices from distinct sets has distance at least . Then there exist some such that every graph with no -quasi-isometry to a graph of tree-width at most contains connected sets that are pairwise at least apart and such that for every pair , there exist no balls of radius at most hitting all paths between and . Coarse connectivity witness conjecture.
This proposes a coarse analogue of the connectivity-witness step in proofs of the classical grid theorem. The paper explains that the coarse Menger step fails, but leaves this alternative structural statement open.
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Sources & referencesView supporting material
Primary source
Sandra Albrechtsen and James Davies, “Counterexample to the conjectured coarse grid theorem”, arXiv:2508.15342 (2026).
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