# delta system lemma

If $S$ is a set of finite sets such that $|S|=\aleph_{1}$ then there is a $S^{\prime}\subseteq S$ such that $|S^{\prime}|=\aleph_{1}$ and $S$ is a http://planetmath.org/node/DeltaSystem$\Delta$-system.

Title delta system lemma DeltaSystemLemma 2013-03-22 12:55:00 2013-03-22 12:55:00 Henry (455) Henry (455) 6 Henry (455) Theorem msc 03E99 DeltaSystem