The Burr-Erdős conjecture asserts that, for each fixed nonnegative integer ,
there is a constant
such that every simple graph
on
vertices and with graph
degeneracy at most
has Ramsey number at most
(Burr and Erdős 1975). Here the Ramsey number
is the least
such that every two-coloring of the edges of
contains a monochromatic copy of
. A graph of graph
degeneracy at most
has a graph vertex of vertex
degree at most
in every nonempty subgraph.
Lee (2017) proved the conjecture. Thus bounded degeneracy suffices for a Ramsey number that is linear in the number of vertices, even when the maximum vertex degree is unbounded.
This is problem 163 in the Erdős problems collection (Bloom 2026).