most recent 30 from http://mathoverflow.net 2013-05-24T22:37:17Z http://mathoverflow.net/feeds/user/12171 http://www.creativecommons.org/licenses/by-nc/2.5/rdf http://mathoverflow.net/questions/51799/describing-a-set-of-normals NilsD 2011-01-12T00:19:28Z 2011-01-12T00:19:28Z

<p>In a finite dimensional (think Euclidean) ambient space, let $S$ a compact, convex set and $x$ not in $S$. The two sets can be (weakly) separated, i.e. there exists a vector (normal) that defines a hyperplane separating the point and the set. In fact, there exists an entire (open) set of normals that separate the point and the set. How can one describe this set?</p>