Long-subdivision extraction conjecture for digraphs

For a digraph DD, write δ+(D)\delta^+(D) for its minimum out-degree. A subdivision-path is a directed path replacing an arc in a subdivision.

Long-subdivision extraction conjecture. There is a function f:NNf:\mathbb{N}\rightarrow\mathbb{N} such that for every kNk\in\mathbb{N} and every digraph DD with

δ+(D)f(k),\delta^+(D)\geq f(k),

there exists a digraph DD' with δ+(D)k\delta^+(D')\geq k such that DD contains a subdivision of DD' in which every subdivision-path has length at least two.

The statement would imply the preceding subdivision-preservation conjecture, but is itself unresolved in the supplied text.

Sources & referencesView supporting material

Primary source

Lior Gishboliner, Raphael Steiner and Tibor Szabó, “Oriented cycles in digraphs of large outdegree”, arXiv:2008.13224 (2020).

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