Maps from Grassmannians of 2-planes to projective spaces

Abstract

Using quaternions and octonions, we construct some maps from the Grassmannian of 2-dimensional planes of ${\mathbb{R}}^n$, ${\mathrm{Gr}}_2({\mathbb{R}}^n)$, to the projective space $\mathbb{R}{\mathrm{P}}^k$, for certain values of $n$ and $k$. All of our maps induce an isomorphism at the level of fundamental groups, and two of them are shown to be submersions. As an application, we obtain new estimates of the Lusternik-Schnirelmann category of ${\mathrm{Gr}}_2({\mathbb{R}}^n)$ for specific values of $n$.

arXiv comment12 pages