<?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>2026-06-27T15:21:57Z</responseDate><request verb="GetRecord" identifier="oai:docta.ucm.es:20.500.14352/60622" metadataPrefix="mods">https://docta.ucm.es/rest/oai/request</request><GetRecord><record><header><identifier>oai:docta.ucm.es:20.500.14352/60622</identifier><datestamp>2023-09-07T20:54:04Z</datestamp><setSpec>com_20.500.14352_14</setSpec><setSpec>col_20.500.14352_21</setSpec></header><metadata><mods:mods xmlns:mods="http://www.loc.gov/mods/v3" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:doc="http://www.lyncode.com/xoai" xsi:schemaLocation="http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-1.xsd">
   <mods:name>
      <mods:namePart>Aguirre Dabán, Eduardo</mods:namePart>
   </mods:name>
   <mods:extension>
      <mods:dateAvailable encoding="iso8601">2023-06-20T21:04:27Z</mods:dateAvailable>
   </mods:extension>
   <mods:extension>
      <mods:dateAccessioned encoding="iso8601">2023-06-20T21:04:27Z</mods:dateAccessioned>
   </mods:extension>
   <mods:originInfo>
      <mods:dateIssued encoding="iso8601">1994</mods:dateIssued>
   </mods:originInfo>
   <mods:identifier type="isbn">84-7491-510-4</mods:identifier>
   <mods:identifier type="uri">https://hdl.handle.net/20.500.14352/60622</mods:identifier>
   <mods:abstract>This note is derived from lectures on cosmology given at the Complutense University of Madrid, basically aimed at a  mathematical audience.
The author derives the geometrical properties of a cosmological model from a set of seven postulates H1 to H7. At large scales a cosmic ﬂuid is represented by a vector ﬁeld Z whose integral curves deﬁne a congruence of geodesics. The cosmic time and the Hubble parameter are deﬁned in terms of such congruence. The ﬁrst three hypotheses concern the homogeneity and isotropy of the model. The age of the Universe and the singularity problem are dealt with in hypothesis H4, and H5 is on the behaviour of Z and on the positivity of the Ricci curvature.
Einstein’s equations appear only at the end with H6.</mods:abstract>
   <mods:accessCondition type="useAndReproduction">metadata only access</mods:accessCondition>
   <mods:titleInfo>
      <mods:title>Geometry of standard cosmology. The initial singularity</mods:title>
   </mods:titleInfo>
   <mods:genre>book part</mods:genre>
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