The ultra-fat half-grid conjecture for quasi-transitive locally finite graphs

From papers

Let GG be a connected, quasi-transitive, locally finite graph. An end of GG is thick if it contains infinitely many pairwise disjoint rays, and an ultra-fat model of the half-grid is a model of the half-grid in GG satisfying the ultra-fatness condition defined in the paper.

Ultra-fat half-grid conjecture. Every connected, quasi-transitive, locally finite graph with a thick end contains an ultra-fat model of the half-grid.

This assertion would suffice to extend the equivalence between the existence of a thick end, the presence of the half-grid as an ultra-fat, asymptotic, or diverging minor, and failure to be quasi-isometric to a tree from accessible graphs to all connected, quasi-transitive, locally finite graphs. Its status is not resolved in the supplied text.

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Sources & referencesView supporting material

Primary source

Sandra Albrechtsen and Matthias Hamann, “A coarse Halin Grid Theorem with applications to quasi-transitive, locally finite graphs”, arXiv:2507.12973 (2026).

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