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SUMMARY:Ana Cristina Castro Ferreira (University of Minho)
DTSTART:20261118T160000Z
DTEND:20261118T170000Z
DTSTAMP:20260603T022701Z
UID:VSGS/139
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/VSGS/139/">I
 sometries of 3-Dimensional Semi-Riemannian Lie Groups</a>\nby Ana Cristina
  Castro Ferreira (University of Minho) as part of Virtual seminar on geome
 try with symmetries\n\n\nAbstract\nLet $G$ be a connected\, simply connect
 ed three-dimensional Lie group (unimodular or non-unimodular) equipped wit
 h a left-invariant (Riemannian or Lorentzian) metric $g$. By definition\, 
 the isometry group $Isom(G\, g)$ contains $G$ itself\, acting by left tran
 slations. It turns out that\, generically\, $Isom(G\, g)$ is actually equa
 l to $G$\, and the natural question then becomes to classify those special
  metrics for which this is not the case. Using Lie-theoretical methods\, w
 e present a unified approach to obtain all pairs $(G\, g)$ whose full isom
 etry group $Isom(G\, g)$ has dimension greater than or equal to four. As a
  consequence\, we determine\, for every pair $(G\, g)$\, up to automorphis
 m and scaling\, the dimension of $Isom(G\, g)$\, which can be three\, four
 \, or six. (Joint work with S. Chaib and A. Zeghib).\n
LOCATION:https://researchseminars.org/talk/VSGS/139/
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