{ "id": "2312.04537", "version": "v1", "published": "2023-12-07T18:55:30.000Z", "updated": "2023-12-07T18:55:30.000Z", "title": "Crouzeix's conjecture, compressions of shifts, and classes of nilpotent matrices", "authors": [ "Kelly Bickel", "Georgia Corbett", "Annie Glenning", "Changkun Guan", "Martin Vollmayr-Lee" ], "comment": "28 pages", "categories": [ "math.FA", "math.CV" ], "abstract": "This paper studies the level set Crouzeix conjecture, which is a weak version of Crouzeix's conjecture that applies to finite compressions of the shift. Amongst other results, this paper establishes the level set Crouzeix conjecture for several classes of $3\\times3$, $4\\times4$, and $5\\times5$ matrices associated to compressions of the shift via a geometric analysis of their numerical ranges. This paper also establishes Crouzeix's conjecture for several classes of nilpotent matrices whose studies are motivated by related compressions of shifts.", "revisions": [ { "version": "v1", "updated": "2023-12-07T18:55:30.000Z" } ], "analyses": { "subjects": [ "47A12", "47A25", "30J10", "15A60" ], "keywords": [ "nilpotent matrices", "level set crouzeix conjecture", "establishes crouzeixs conjecture", "paper studies", "weak version" ], "note": { "typesetting": "TeX", "pages": 28, "language": "en", "license": "arXiv", "status": "editable" } } }