Relative singular value decomposition and applications to LS-category

E. Macías-Virgós, M. J. Pereira-Sáez, Daniel Tanré

Let $Sp(n)$ be the symplectic group of quaternionic $(n\times n)$-matrices. For any $1\le k\le n$, an element $A$ of $Sp(n)$ can be decomposed in $A= \begin{bmatrix} α&T\cr β&P \…