Problems / combinatorics
combinatorics / Graph theory
Erdős Problem #74: locally almost bipartite graphs of infinite chromatic number
Astra proves that there exists a divergent function
f:N→N,f(n)→∞,
such that no graph G of infinite chromatic number can satisfy
dbip(H)≤f(n)
for every finite n-vertex subgraph H⊆G, where dbip(H) is the minimum number of edges that must be deleted to make H bipartite.
In fact, every included resolution proves the stronger statement that graphs satisfying the constructed local bound are 3-colorable. The formal challenge advertises only the weaker conclusion that their chromatic number must be finite.