Research notes on every problem, and a library of the papers behind them. Built from the open erdos repository.
Updated
Claims
2013_01_03_komjath: Forces a graph of size and chromatic number aleph one with no uncountable infinitely connected subgraph, so a negative answer is consistent; refereed in 2013 and superseded by Soukup's ZFC counterexample.
2014_09_09_soukup: Builds, with no extra axioms, a graph of chromatic number aleph one in which no uncountable set of vertices is infinitely connected, so the problem's question has a negative answer; refereed in 2015 and credited by the site.
2024_02_08_bowler_pitz: Gives a short construction of a graph of chromatic number aleph one in which every uncountable set of vertices has two vertices joined by only finitely many independent paths; refereed in 2025, formalized by others.