The Grassmannian is the space of orthographic projections from a Euclidean space to one of lower dimension; the set of k-dimensional planes passing through the origin in E^n. By forbidden arc (my mistake, it has more than one degree of freedom) I mean a continuous set of projections that make the images of some elements collide.
Refurio Anachro (npub17lw…5ctv) 0xDE (npub1p5z…4d3n)