Generalized Hopfian Property, a Minimal Haken Manifold, and Epimorphisms Between 3-Manifold Groups

(整期优先)网络出版时间:2002-01-11
/ 1
<正>Weaddressthequestionthatifπ1-surjectivemapsbetweenclosedaspherical3-manifoldshavethesamerankonπ1theymustbeofnon-zerodegree.ThepositiveanswerisprovedforSeifertmanifolds,whichisusedinconstructingthefirstknownexampleofminimalHakenmanifold.Anothermotivationistostudyepimorphismsof3-manifoldgroupsviamapsofnon-zerodegreebetween3-manifolds.Manyexamplesaregiven.