Dipartimento di Matematica, Aula Seminari.
Zarankiewicz’s problem for hypergraphs asks for upper bounds on the number of edges of a hypergraph that has no complete sub-hypergraphs of a given size. Let M be an o-minimal structure. Basit-Chernikov-Starchenko-Tao-Tran (2021) proved that the following are equivalent:
(1) “linear Zarankiewicz’s bounds” hold for hypergraphs whose edge relation is induced by a fixed relation definable in M
(2) M does not define an infinite field.
We prove that the following are equivalent:
(1′) linear Zarankiewicz bounds hold for sufficiently “distant” hypergraphs whose edge relation is induced by a fixed relation definable in M
(2′) M does not define a full field (that is, one whose domain is the whole universe of M).
This is joint work (in progress) with Aris Papadopoulos.
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