{ "id": "1704.05142", "version": "v1", "published": "2017-04-17T22:40:54.000Z", "updated": "2017-04-17T22:40:54.000Z", "title": "Surjective homomorphisms between surface braid groups", "authors": [ "Lei Chen" ], "comment": "8 pages", "categories": [ "math.GT" ], "abstract": "Let $PB_n(S_{g,p})$ be the pure braid group of a genus $g>1$ surface with $p$ punctures. In this paper we prove that any surjective homomorphism $PB_n(S_{g,p})\\to PB_m(S_{g,p})$ factors through one of the forgetful homomorphisms. We then compute the automorphism group of $PB_n(S_{g,p})$, extending Irmak, Ivanov and McCarthy's result \\cite{ivanov} to the punctured case. Surprisingly, in contrast to the $n=1$ case, any automorphism of $PB_n(S_{g,p})$, $n>1$ is geometric.", "revisions": [ { "version": "v1", "updated": "2017-04-17T22:40:54.000Z" } ], "analyses": { "keywords": [ "surface braid groups", "surjective homomorphism", "pure braid group", "automorphism group", "mccarthys result" ], "note": { "typesetting": "TeX", "pages": 8, "language": "en", "license": "arXiv", "status": "editable" } } }