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Absolutely Flat Idempotents

Jonathan M. Groves·Yonatan Harel·Christopher J. Hillar·Charles R. Johnson·Patrick X. Rault
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Abstract

A real $n$-by-$n$ idempotent matrix $A$ with all entries having the same absolute value is called {\it absolutely flat}. We consider the possible ranks of such matrices and herein characterize the triples: size, constant, and rank for which such a matrix exists. Possible inequivalent examples of such matrices are also discussed.

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Jonathan M. Groves, Yonatan Harel, Christopher J. Hillar, Charles R. Johnson, Patrick X. Rault. 2005-04-28. Absolutely Flat Idempotents. https://arxiv.org/abs/math/0504572

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