Open Access
2004 On representability of the smooth Euler class
Shigeaki Miyoshi
Tohoku Math. J. (2) 56(4): 523-530 (2004). DOI: 10.2748/tmj/1113246748

Abstract

The Euler class, which lies in the second cohomology of the group of orientation preserving homeomorphisms of the circle, is pulled back to the "smooth'' Euler class in the cohomology of the group of orientation preserving smooth diffeomorphisms of the circle. Suppose a surface group $\Gamma$ (of genus $> 1$) is a normal subgroup of a group $G$, so that we have an extension of $Q = G/\Gamma$ by $\Gamma$. We prove that if the canonical outer action of $Q$ on $\Gamma$ is finite, then there is a canonical second cohomology class of $G$ restricting to the Euler class on $\Gamma$ which is smoothly representable, that is, it is pulled back from the smooth Euler class by a representation from $G$ to the group of diffeomorphisms. Also, we prove that if the above outer action is infinite, then any second cohomology class of $G$ restricting to the Euler class on $\Gamma$ is not smoothly representable

Citation

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Shigeaki Miyoshi. "On representability of the smooth Euler class." Tohoku Math. J. (2) 56 (4) 523 - 530, 2004. https://doi.org/10.2748/tmj/1113246748

Information

Published: 2004
First available in Project Euclid: 11 April 2005

zbMATH: 1072.57021
MathSciNet: MR2097159
Digital Object Identifier: 10.2748/tmj/1113246748

Subjects:
Primary: 57M60
Secondary: 57R20 , 57R30

Keywords: Euler classes , Foliated circle bundles , Fuschsian groups

Rights: Copyright © 2004 Tohoku University

Vol.56 • No. 4 • 2004
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