# delta system

If $S$ is a set of finite sets then it is a $\Delta$-system if there is some (possibly empty) $X$ such that for any $a,b\in S$, if $a\neq b$ then $a\cap b=X$.

Title delta system DeltaSystem 2013-03-22 12:54:57 2013-03-22 12:54:57 Henry (455) Henry (455) 5 Henry (455) Definition msc 03E99 DeltaSystemLemma