PPL 068 / 177 permanent IDsPrize Problem Ledger · PPLChecked 2026.07.26
Prize Problem LedgerErdősPPL 068Erdős Problem #625

Permanent problem IDPPL 068

Verified openErdősconjecture

Graph theory

Erdős Problem #625

The cochromatic number of G, denoted by ζ(G), is the minimum number of colours needed to colour the vertices of G such that each colour class induces either a complete graph or empty graph. Let χ(G) denote the chromatic number. If G is a random graph with n vertices and each edge included independently with probability 1/2 then is it true that almost surely χ(G) - ζ(G) → ∈fty as n→ ∈fty?

graph theorychromatic number
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The problem

The cochromatic number of G, denoted by ζ(G), is the minimum number of colours needed to colour the vertices of G such that each colour class induces either a complete graph or empty graph. Let χ(G) denote the chromatic number. If G is a random graph with n vertices and each edge included independently with probability 1/2 then is it true that almost surely χ(G) - ζ(G) → ∈fty as n→ ∈fty?

Open since1989approximate
Last checked2026.07.26Catalog verification
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Reward offers

Offer 01$1000Paul Erdős / Combinatorics Foundation
Documented

A solution must appear in a reputable journal, with documentation that Erdős offered the displayed amount. Claims are administered by the Combinatorics Foundation; erdosproblems.com does not pay awards.

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Sources & reading