English

Diagonal and off-diagonal blocks of positive definite partitioned matrices

Functional Analysis 2023-12-18 v3

Abstract

We establish a sharp inequality between the blocks of positive partitioned matrices and conjecture a triangle type inequality for contractions: Given three contactions A,B,C, we conjecture that the constant c=3/4 is sharp in the triangle inequality |A+B+C| < cI + |A| +|B| + |C|.

Keywords

Cite

@article{arxiv.2307.02034,
  title  = {Diagonal and off-diagonal blocks of positive definite partitioned matrices},
  author = {Jean-Christophe Bourin and Eun-Young Lee},
  journal= {arXiv preprint arXiv:2307.02034},
  year   = {2023}
}

Comments

Final version, to appear in LAA, 13 pages