Hello All, It's rather a simple question for advanced people. Consider a 3D Euclidean space: if one is given 2 points, a line can be build that goes through the points; for 3 points -- there is a plane. For 4D space: a line goes through 2 points and a hyperplane through 4 points. The question -- what's the name for the object that can be build with given 3 points in 4D space? And more generally, for (N-i) points, 1<i<N-2, in N-dimensional space? Where can I look for more info on this topic. Thanks in advance!