Quasimorphisms on nonorientable surface diffeomorphism groups

Fuente: arXiv
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Autores principales: Kimura, Mitsuaki, Kuno, Erika
Formato: Preprint
Publicado: 2021
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author Kimura, Mitsuaki
Kuno, Erika
author_facet Kimura, Mitsuaki
Kuno, Erika
contents Bowden, Hensel, and Webb constructed infinitely many quasimorphisms on the diffeomorphism groups of orientable surfaces. In this paper, we extend their result to nonorientable surfaces. Namely, we prove that the space of nontrivial quasimorphisms $\widetilde{QH}(\mathrm{Diff}_0(N_g))$ on the identity component of the diffeomorphism group $\mathrm{Diff}_0(N_g)$ on a closed nonorientable surface $N_g$ of genus $g\geq 3$ is infinite-dimensional. As a corollary, we obtain the unboundedness of the commutator length and the fragmentation length on $\mathrm{Diff}_0(N_g)$.
format Preprint
id arxiv_https___arxiv_org_abs_2111_05540
institution arXiv
publishDate 2021
record_format arxiv
spellingShingle Quasimorphisms on nonorientable surface diffeomorphism groups
Kimura, Mitsuaki
Kuno, Erika
Geometric Topology
Group Theory
20F65, 57K20, 57S05
Bowden, Hensel, and Webb constructed infinitely many quasimorphisms on the diffeomorphism groups of orientable surfaces. In this paper, we extend their result to nonorientable surfaces. Namely, we prove that the space of nontrivial quasimorphisms $\widetilde{QH}(\mathrm{Diff}_0(N_g))$ on the identity component of the diffeomorphism group $\mathrm{Diff}_0(N_g)$ on a closed nonorientable surface $N_g$ of genus $g\geq 3$ is infinite-dimensional. As a corollary, we obtain the unboundedness of the commutator length and the fragmentation length on $\mathrm{Diff}_0(N_g)$.
title Quasimorphisms on nonorientable surface diffeomorphism groups
topic Geometric Topology
Group Theory
20F65, 57K20, 57S05
url https://arxiv.org/abs/2111.05540