
For the fundamental group \(\Gamma\) of a flat manifold \(M\) (=a Bieberbach group), the paper gives necessary and sufficient conditions on \(\text{Out}(\Gamma)\) to be infinite. It also compares that result with a previous one due to \textit{H. L. Porteous} [Topology 11, 307-315 (1972; Zbl 0237.58015)], and gives several applications and examples of Bieberbach groups that have either finite, or infinite \(\text{Out}(\Gamma)\), and are quasi-isometric to \(\text{GL}(n-1,\mathbb{Z})\), whose flat manifold \(M\) either have or have not Anosov automorphisms.
Fundamental group, presentations, free differential calculus, Discontinuous groups of transformations, Other geometric groups, including crystallographic groups, Groups of diffeomorphisms and homeomorphisms as manifolds, 20F34, Automorphisms of infinite groups, flat manifolds, Anosov automorphisms, Differential topological aspects of diffeomorphisms, 57S30, Fundamental groups and their automorphisms (group-theoretic aspects), outer automorphism groups, Bieberbach groups, fundamental groups
Fundamental group, presentations, free differential calculus, Discontinuous groups of transformations, Other geometric groups, including crystallographic groups, Groups of diffeomorphisms and homeomorphisms as manifolds, 20F34, Automorphisms of infinite groups, flat manifolds, Anosov automorphisms, Differential topological aspects of diffeomorphisms, 57S30, Fundamental groups and their automorphisms (group-theoretic aspects), outer automorphism groups, Bieberbach groups, fundamental groups
| selected citations These citations are derived from selected sources. This is an alternative to the "Influence" indicator, which also reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically). | 8 | |
| popularity This indicator reflects the "current" impact/attention (the "hype") of an article in the research community at large, based on the underlying citation network. | Average | |
| influence This indicator reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically). | Top 10% | |
| impulse This indicator reflects the initial momentum of an article directly after its publication, based on the underlying citation network. | Average |
