A criterion of contractivity for four by four upper-triangular matrices

Axel Renard

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arXiv · 2506.10485

A criterion of contractivity for four by four upper-triangular matrices

Axel Renard

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Abstract

We establish an explicit criterion for determining whether a $4 \times 4$ upper-triangular matrix is a contraction with respect to the Euclidean operator norm.

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Axel Renard. 2025-06-12. A criterion of contractivity for four by four upper-triangular matrices. https://arxiv.org/abs/2506.10485

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