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FormalConjectures.ErdosProblems.«1077»

Erdős Problem 1077 #

Reference: erdosproblems.com/1077

theorem Erdos1077.erdos_1077 :
(∀ (ε α : ), ε > 0α > 0∃ (D0 : ) (n0 : ), D > D0, n > n0, ∀ (G : SimpleGraph (Fin n)), G.edgeFinset.card > n ^ (1 + α) → ∃ (H : G.Subgraph), H.coe.IsBalanced D H.verts.toFinset.card > n ^ (1 - α) H.edgeSet.toFinset.card > ε * H.verts.toFinset.card ^ (1 + α)) sorry

We call a graph $D$-balanced (or $D$-almost-regular) if the maximum degree is at most $D$ times the minimum degree.

Let $ϵ, α > 0$ and $D$ and $n$ be sufficiently large. If $G$ is a graph on $n$ vertices with at least $n^{1+α}$ edges, then must $G$ contain a $D$-balanced subgraph on $m > n^{1-α}$ vertices with at least $ϵm^{1+α}$ edges?