Affiliation: | 1. Dpto. Matemática Aplicada I., Universidad de Sevilla, Sevilla, Spainlcamacho@us.eshttps://orcid.org/0000-0002-0232-643X;3. Department of Algebra and Functional Analysis, National University of Uzbekistan, Tashkent, Uzbekistan;4. Institute of Mathematics of Uzbek Academy of Sciences, Tashkent, Uzbekistan |