Normal subgroups of mapping class groups and the metaconjecture of Ivanov
| Autor: | Tara E. Brendle, Dan Margalit |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2019 |
| Předmět: |
Normal subgroup
Class (set theory) Group (mathematics) Applied Mathematics General Mathematics 010102 general mathematics Commensurator 16. Peace & justice Surface (topology) Object (computer science) 01 natural sciences Mapping class group Combinatorics Mathematics::Group Theory 0103 physical sciences 010307 mathematical physics 0101 mathematics Element (category theory) Mathematics |
| ISSN: | 0894-0347 |
| Popis: | We prove that if a normal subgroup of the extended mapping class group of a closed surface has an element of sufficiently small support, then its automorphism group and abstract commensurator group are both isomorphic to the extended mapping class group. The proof relies on another theorem we prove, which states that many simplicial complexes associated to a closed surface have automorphism group isomorphic to the extended mapping class group. These results resolve the metaconjecture of N. V. Ivanov, which asserts that any “sufficiently rich” object associated to a surface has automorphism group isomorphic to the extended mapping class group, for a broad class of such objects. As applications, we show: (1) right-angled Artin groups and surface groups cannot be isomorphic to normal subgroups of mapping class groups containing elements of small support, (2) normal subgroups of distinct mapping class groups cannot be isomorphic if they both have elements of small support, and (3) distinct normal subgroups of the mapping class group with elements of small support are not isomorphic. Our results also suggest a new framework for the classification of normal subgroups of the mapping class group. |
| Databáze: | OpenAIRE |
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