130798 20251113150202.0 doi 10.1007/s43037-020-00114-6 sideral 122483 ART-2021-122483 eng Abadias, L. Universidad de Zaragoza (orcid)0000-0003-2453-7841 Functional models up to similarity and a-contractions 2021 We study the generalization of m-isometries and m-contractions (for positive integers m) to what we call a-isometries and a-contractions for positive real numbers a. We show that an operator satisfying a certain inequality in hereditary form is similar to a-contraction. This improvement of [9, Theorem I] is based on some Banach algebras techniques. We show that our operator classes are closely connected with fractional finite differences. Using this techniques, we get that, given 0 < b< a, an a-contraction need not to be a b-contraction in general, but is a b-contraction if a natural additional requirement is imposed. info:eu-repo/grantAgreement/ES/DGA-FEDER/E26-17R info:eu-repo/grantAgreement/ES/MINECO-MCIU/PID2019-105979GB-I00 info:eu-repo/semantics/closedAccess All rights reserved http://www.europeana.eu/rights/rr-f/ 1.197 2021 MATHEMATICS 114 / 333 = 0.342 2021 Q2 T2 MATHEMATICS, APPLIED 166 / 267 = 0.622 2021 Q3 T2 0.554 2021 Analysis 2021 Q2 Algebra and Number Theory 2021 Q2 1.6 2021 info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion Bello, G. (orcid)0000-0001-6249-9247 Yakubovich, D. 2006 015 Universidad de Zaragoza Dpto. Matemáticas Área Análisis Matemático 15, 2 (2021), 34 [29 pp] Banach Journal of Mathematical Analysis Banach Journal of Mathematical Analysis 2662-2033 4052840 http://zaguan.unizar.es/record/130798/files/texto_completo.pdf Versión publicada 1063527 http://zaguan.unizar.es/record/130798/files/texto_completo.jpg?subformat=icon icon Versión publicada oai:zaguan.unizar.es:130798 articulos driver 2025-11-13-15:00:39 ARTICLE