Real lines tangent to 2n-2 quadrics in Rn

Frank Sottile and Thorsten Theobald.

Let Cn,k be the number of k-flats in Pn which meet N := (k+1)(n-k) general linear subspaces of codimension k. We show that for each n>k there are 2N Cn,k k-flats in Pn tangent to N general quadric hypersurfaces in Pn, and that there exists a configuration of N real quadrics so that all the mutually tangent k-flats are real.



The manuscript in postscript.
Previous