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SUMMARY:Andrzej Derdzinski (Ohio State Univ.)
DTSTART:20210923T140000Z
DTEND:20210923T150000Z
DTSTAMP:20260417T104800Z
UID:CHEM/5
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/CHEM/5/">Cur
 vature-homogeneous pseudo-Riemannian Einstein four-manifolds</a>\nby Andrz
 ej Derdzinski (Ohio State Univ.) as part of Workshop on compact homogeneou
 s Einstein manifolds\n\n\nAbstract\nIn the Riemannian case they are all lo
 cally homogeneous (and hence locally\nsymmetric due to a 1969 result of Je
 nsen). By contrast\, for the neutral sign\npattern $(- - + +)$\, simple ex
 amples show that the local-isometry types of\ncurvature-homogeneous Ricci-
 flat metrics form an in finite-dimensional moduli\nspace (and so "most" of
  them are not locally homogeneous). In the Lorentzian\nsignature\, the sam
 e phenomenon arises as a consequence of Brans's 1971\nclassification of Pe
 trov type III metrics. The talk presents local-structure\ntheorems for som
 e special classes of such four-manifolds.\n
LOCATION:https://researchseminars.org/talk/CHEM/5/
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