Outer automorphism groups of equivalence relations for mapping class group actions

• Autores: Yoshikata Kida
• Localización: Journal of the London Mathematical Society, ISSN 0024-6107, Vol. 78, Nº 3, 2008, págs. 622-638
• Idioma: inglés
• DOI: 10.1112/jlms/jdn042
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• Resumen

  • We study outer automorphism groups Out() of equivalence relations arising from ergodic, essentially free and measure-preserving actions on standard probability spaces of mapping class groups, and compute them explicitly for some examples. We show that the subgroups of Out() associated with action-automorphisms are always finite index ones. Moreover, a sharp upper bound of the indices among all such actions of mapping class groups is obtained