Abstract
We prove that one cannot algorithmically decide whether a finitely presented extension admits a finitely generated base group, and we use this fact to prove the undecidability of the BNS invariant. Furthermore, we show the equivalence between the isomorphism problem within the subclass of unique extensions, and the semi-conjugacy problem for deranged outer automorphisms.
Original language | English |
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Pages (from-to) | 2157-2179 |
Number of pages | 22 |
Journal | Journal of Pure and Applied Algebra |
Early online date | 25 Oct 2016 |
DOIs | |
Publication status | Published - 2017 |