{ "id": "math/0101182", "version": "v2", "published": "2001-01-22T23:32:55.000Z", "updated": "2001-01-26T21:54:16.000Z", "title": "Invariance properties of thematic factorizations of matrix functions", "authors": [ "R. B. Alexeev", "V. V. Peller" ], "comment": "20 pages", "categories": [ "math.FA", "math.CA", "math.CV" ], "abstract": "We study the problem of invariance of indices of thematic factorizations. Such factorizations were introduced in [PY1] for studying superoptimal approximation by bounded analytic matrix functions. As shown in [PY1], the indices may depend on the choice of a thematic factorization. We introduce the notion of a monotone thematic factorization. The main result shows that under natural assumptions a matrix function that admits a thematic factorization also admits a monotone thematic factorization and the indices of a monotone thematic factorization are uniquely determined by the matrix function itself. We obtain similar results for so-called partial thematic factorizations.", "revisions": [ { "version": "v2", "updated": "2001-01-26T21:54:16.000Z" } ], "analyses": { "subjects": [ "47B35", "46E15", "30D55" ], "keywords": [ "monotone thematic factorization", "invariance properties", "partial thematic factorizations", "bounded analytic matrix functions", "main result" ], "note": { "typesetting": "TeX", "pages": 20, "language": "en", "license": "arXiv", "status": "editable", "adsabs": "2001math......1182A" } } }