Menger's n-Arc Theorem

Let $G$ be a graph with $A$ and $B$ two disjoint $n$-tuples of Vertices. Then either $G$ contains $n$ pairwise disjoint $AB$-paths, each connecting a point of $A$ and a point of $B$, or there exists a set of fewer than $n$ Vertices that separate $A$ and $B$.

References

Menger, K. Kurventheorie. Leipzig, Germany: Teubner, 1932.