Characterization of zero uniform Turán density for r-graphs

From papers

Let FF be an rr-graph. An ordering \preceq on V(F)V(F) and a function

φ:(V(F)2)([r]2)\varphi:\binom{V(F)}{2}\rightarrow\binom{[r]}{2}

assign to each pair of vertices the role it plays in an edge containing that pair. The zero-density characterization conjecture.

π ⁣uniform(F)=0\pi_{\!\text{uniform}}(F)=0

if and only if there exists an ordering \preceq on V(F)V(F) and such a function φ\varphi with the property that, for each pair of vertices u,vu,v and every edge ee containing uu and vv, the pair {u,v}\{u,v\} plays the role φ(uv)\varphi(uv) in ee.

For 33-graphs, Reiher, Rödl and Schacht proved the analogous characterization. Extending it to rr-graphs for general rr would characterize exactly the forbidden hypergraphs of zero uniform Turán density; the general case is left open in the source.

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Sources & referencesView supporting material

Primary source

Ander Lamaison, “Uniform Turán density beyond 3-graphs”, arXiv:2508.20696 (2025).

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