Given a presentation of a group, find its normalizer.












2














Let $F$ and $H$ be two free groups, where $F = langle a,brangle$ and $H = langle aa,bb,aba,baab, bababrangle$. Let $N(H)$ be the normalizer of $H$ in $F$.



How can I compute $N(H)/H$?



In general, given a presentation of a group, is there a way to find its normalizer?










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  • 2




    In general, questions about finitely presented groups are typically undecidable, and the answer is no. There is an algorithm for calculating the normalizer of a finitely generated subgroup of a free group.But the specific problem you ask is rather easy. As a hint, $|F:H|$ is finite.
    – Derek Holt
    Apr 29 '17 at 8:18


















2














Let $F$ and $H$ be two free groups, where $F = langle a,brangle$ and $H = langle aa,bb,aba,baab, bababrangle$. Let $N(H)$ be the normalizer of $H$ in $F$.



How can I compute $N(H)/H$?



In general, given a presentation of a group, is there a way to find its normalizer?










share|cite|improve this question




















  • 2




    In general, questions about finitely presented groups are typically undecidable, and the answer is no. There is an algorithm for calculating the normalizer of a finitely generated subgroup of a free group.But the specific problem you ask is rather easy. As a hint, $|F:H|$ is finite.
    – Derek Holt
    Apr 29 '17 at 8:18
















2












2








2


1





Let $F$ and $H$ be two free groups, where $F = langle a,brangle$ and $H = langle aa,bb,aba,baab, bababrangle$. Let $N(H)$ be the normalizer of $H$ in $F$.



How can I compute $N(H)/H$?



In general, given a presentation of a group, is there a way to find its normalizer?










share|cite|improve this question















Let $F$ and $H$ be two free groups, where $F = langle a,brangle$ and $H = langle aa,bb,aba,baab, bababrangle$. Let $N(H)$ be the normalizer of $H$ in $F$.



How can I compute $N(H)/H$?



In general, given a presentation of a group, is there a way to find its normalizer?







group-theory free-groups group-presentation combinatorial-group-theory






share|cite|improve this question















share|cite|improve this question













share|cite|improve this question




share|cite|improve this question








edited Nov 30 at 1:56









Shaun

8,507113580




8,507113580










asked Apr 29 '17 at 5:04









Yuliya

132




132








  • 2




    In general, questions about finitely presented groups are typically undecidable, and the answer is no. There is an algorithm for calculating the normalizer of a finitely generated subgroup of a free group.But the specific problem you ask is rather easy. As a hint, $|F:H|$ is finite.
    – Derek Holt
    Apr 29 '17 at 8:18
















  • 2




    In general, questions about finitely presented groups are typically undecidable, and the answer is no. There is an algorithm for calculating the normalizer of a finitely generated subgroup of a free group.But the specific problem you ask is rather easy. As a hint, $|F:H|$ is finite.
    – Derek Holt
    Apr 29 '17 at 8:18










2




2




In general, questions about finitely presented groups are typically undecidable, and the answer is no. There is an algorithm for calculating the normalizer of a finitely generated subgroup of a free group.But the specific problem you ask is rather easy. As a hint, $|F:H|$ is finite.
– Derek Holt
Apr 29 '17 at 8:18






In general, questions about finitely presented groups are typically undecidable, and the answer is no. There is an algorithm for calculating the normalizer of a finitely generated subgroup of a free group.But the specific problem you ask is rather easy. As a hint, $|F:H|$ is finite.
– Derek Holt
Apr 29 '17 at 8:18

















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