Glasnik matematički, Vol. 42 No. 1, 2007.
Original scientific paper
https://doi.org/10.3336/gm.42.1.15
Quasi-homomorphisms on mapping class groups
Mladen Bestvina
; Department of Mathematics, University of Utah, 155 South 1400 East, JWB 233, Salt Lake City, Utah 84112-0090, USA
Koji Fujiwara
; Graduate School of Information Science, Tohoku University, Sendai, 980-8579, Japan
Abstract
We refine the construction of quasi-homomorphisms on mapping class groups. It is useful to know that there are unbounded quasi-homomorphisms which are bounded when restricted to particular subgroups since then one deduces that the mapping class group is not boundedly generated by these subgroups. In this note we enlarge the class of such subgroups. The generalization is motivated by considerations in first order theory of free groups.
Keywords
Mapping class group; quasi-homomorphism; bounded cohomology; pseudo-Anosov
Hrčak ID:
12896
URI
Publication date:
12.6.2007.
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