Helly family
These concepts are named after Eduard Helly ( 1884-1943 ) ; Helly's theorem on convex sets , which gave rise to this notion , states that convex sets in Euclidean space of dimension "n" are a Helly family of order "n" + 1 . 
<triplet> Helly's theorem <subj> Eduard Helly <obj> named after <triplet> Helly family <subj> Eduard Helly <obj> named after