79 citations · 132 across the 27 of their papers we have counts for
5 papers · 1 filter
Crossed-Heinz Inequalities: The Two-Dimensional Threshold and Higher-Dimensional Stability
Mohammad Sababheh, Jean-Christophe Bourin
For positive matrices and , Bourin asked whether the crossed-Heinz expression \[ C_t(A,B)=A^tB^{1-t}+B^tA^{1-t} \] satisfies \[ \UIN{C_t(A,B)}\le \UIN{A+B} \] for ever…
Some hybrid matrix triangle inequalities
Jean-Christophe Bourin, Eun-Young Lee
A recent result due to Teng Zhang compares the sum of matrices and the sum of their quadratic symmetric moduli: $$ \left\| \sum_{k=1}^m A_k\right\| \le \sqrt{2} \left\| \sum_{k…
Averages over matrix unitary orbits and spectral order
Jean-Christophe Bourin, Eun-Young Lee
We establish matrix versions of the comparisons between the -norms or quasi-norms for sequences of complex numbers. For instance, given , and a family of norm…
Triangle inequalities for the operator symmetric modulus
Jean-Christophe Bourin, Eun-Young Lee
We study the operator symmetric modulus (|Z|+|Z^*|)/2 for matrices Z. Several triangle type inequalities are given.
Involutions and angles between subspaces
Jean-Christophe Bourin, Eun-Young Lee
We provide a complete structure theorem for involutory matrices. This yields a new approach to principal angles between subspaces and provide a series of nice formulae for these an…