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Questions about the group of automorphisms of any mathematical object $X$ endowed with a given structure, i.e the group of all bijective maps from $X$ to itself preserving this structure, and hence helping study it further and understand it better.

11 votes
Accepted

Automorphism group of a free product

This is not an answer, but it's too long for a comment and makes an important point that I hope is useful. It's not enough to think of your group just as some free product. To understand its automorph …
HJRW's user avatar
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21 votes
Accepted

Does the injection $\text{Aut}(F_n) \hookrightarrow \text{Aut}(F_{n+1})$ split?

Bridson and Vogtmann proved a much stronger result. From the abstract: 'If $m$ is less than $n$ then [the image of] a homomorphism $\mathrm{Aut}(F_n)\to\mathrm{Aut}(F_m)$ can have cardinality at most …
HJRW's user avatar
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4 votes
Accepted

Is the conjugacy problem solvable in $Out(F_n)$?

One result in this direction is given by Dahmani . His algorithm will determine conjugacy for pairs of atoroidal outer automorphisms, ie automorphisms that do not fix a non-trivial conjugacy class. …
HJRW's user avatar
  • 25.2k