<?xml version="1.0" encoding="UTF-8"?><?xml-stylesheet type="text/xsl" href="static/style.xsl"?><OAI-PMH xmlns="http://www.openarchives.org/OAI/2.0/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/ http://www.openarchives.org/OAI/2.0/OAI-PMH.xsd"><responseDate>2026-04-05T10:46:02Z</responseDate><request verb="GetRecord" identifier="oai:www.recercat.cat:2072/455949" metadataPrefix="rdf">https://recercat.cat/oai/request</request><GetRecord><record><header><identifier>oai:recercat.cat:2072/455949</identifier><datestamp>2025-10-13T07:24:12Z</datestamp><setSpec>com_2072_98</setSpec><setSpec>col_2072_378192</setSpec></header><metadata><rdf:RDF xmlns:rdf="http://www.openarchives.org/OAI/2.0/rdf/" xmlns:ow="http://www.ontoweb.org/ontology/1#" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:ds="http://dspace.org/ds/elements/1.1/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:doc="http://www.lyncode.com/xoai" xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/rdf/ http://www.openarchives.org/OAI/2.0/rdf.xsd">
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      <dc:title>Phase portraits of uniform isochronous centers with homogeneous nonlinearities</dc:title>
      <dc:creator>Llibre, Jaume</dc:creator>
      <dc:creator>Valls, Clàudia</dc:creator>
      <dc:subject>Polynomial vector field</dc:subject>
      <dc:subject>Uniform isochronous center</dc:subject>
      <dc:subject>Phase portrait</dc:subject>
      <dc:subject>Poincaré disc</dc:subject>
      <dc:description>We classify the phase portraits in the Poincaré disc of the differential equations of the form x' = - y + xf(x, y), ẏ = x + yf(x, y) where f(x,y) is a homogeneous polynomial of degree n - 1 when n = 2, 3, 4, 5, and f has only simple zeroes. We also provide some general results on these uniform isochronous centers for all n ≥ 2. All our results have been revised by the program P4; see Chaps. 9 and 10 of Dumortier et al. (UniversiText, Springer-Verlag, New York, 2006).</dc:description>
      <dc:date>2021</dc:date>
      <dc:type>Article</dc:type>
      <dc:relation>Ministerio de Economía y Competitividad MTM2016-77278-P</dc:relation>
      <dc:relation>Agència de Gestió d'Ajuts Universitaris i de Recerca 2017/SGR-1617</dc:relation>
      <dc:relation>European Commission 777911</dc:relation>
      <dc:relation>Journal of Dynamical and Control Systems ; Vol. 28 (February 2021), p. 319-332</dc:relation>
      <dc:rights>open access</dc:rights>
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      <dc:rights>https://rightsstatements.org/vocab/InC/1.0/</dc:rights>
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