Dual View Random Solved Random Open
PROVED This has been solved in the affirmative.
Let $G$ be a (possibly infinite) graph and $A,B$ be disjoint independent sets of vertices. Must there exist a family $P$ of disjoint paths between $A$ and $B$ and a set $S$ which contains exactly one vertex from each path in $P$, and such that every path between $A$ and $B$ contains at least one vertex from $S$?
Sometimes known as the Erdős-Menger conjecture. When $G$ is finite this is equivalent to Menger's theorem. Erdős was interested in the case when $G$ is infinite.

This was proved by Aharoni and Berger [AhBe09].

View the LaTeX source

External data from the database - you can help update this
Formalised statement? No (Create a formalisation here)
Likes this problem None
Interested in collaborating None
Currently working on this problem None
This problem looks difficult None
This problem looks tractable None

When referring to this problem, please use the original sources of Erdős. If you wish to acknowledge this website, the recommended citation format is:

T. F. Bloom, Erdős Problem #599, https://www.erdosproblems.com/599, accessed 2026-01-16