Erdős problem 753
The list chromatic number is defined to be the minimal such that for any assignment of a list of colours to each vertex of (perhaps different lists for different vertices) a colouring of each vertex by a colour on its list can be chosen such that adjacent vertices receive distinct colours.
Sources
FormalConjectures/ErdosProblems/
753.lean
The list chromatic number is defined to be the minimal such that for any assignment of a list of colours to each vertex of (perhaps different lists for different vertices) a colouring of each vertex by a colour on its list can be chosen such that adjacent vertices receive distinct colours.
Does there exist some constant such that for every graph on vertices (where is the complement of )?
A problem of Erdős, Rubin, and Taylor.
The answer is no: Alon [Al92] proved that, for every , there exists a graph on vertices such that where the implied constant is absolute.
False ↔ ∃ c, 0 < c ∧ ∀ (n : ℕ), 0 < n → ∀ (G : SimpleGraph (Fin n)), ↑n ^ (1 / 2 + c) < ↑(Erdos753.listChromaticNumber G) + ↑(Erdos753.listChromaticNumber Gᶜ)