1 6 Ju n 19 93 Almost Convex Groups and the Eight Geometries
نویسندگان
چکیده
If M is a closed Nil geometry 3-manifold then π 1 (M) is almost convex with respect to a fairly simple " geometric " generating set. If G is a central extension or a Z extension of a word hyperbolic group, then G is also almost convex with respect to some generating set. Combining these with previously known results shows that if M is a closed 3-manifold with one of Thurston's eight geometries, π 1 (M) is almost convex with respect to some generating set if and only if the geometry in question is not Sol.
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