- #1
NasuSama
- 326
- 3
Homework Statement
Let [itex]G[/itex] be a group and let [itex]Aut(G)[/itex] be the group of automorphisms of [itex]G[/itex].
(a) For any [itex]g \in G[/itex], define [itex]\phi_{g}(x) = g^{-1}xg[/itex]. Check that [itex]\phi_{g}(x)[/itex] is an automorphism.
(b) Consider the map:
[itex]\Phi:G \rightarrow Aut(G)[/itex]
[itex]g \mapsto \phi_{g}[/itex]
Check that [itex]\Phi[/itex] is a homomorphism.
2. The attempt at a solution
Evaluate [itex]\Phi[/itex] at gh with arbitrary x, so:
[itex]\Phi(gh) = \phi_{gh}(x) = (gh)^{-1}x(gh) = h^{-1}g^{-1}xgh = \phi_{h}(\phi_{g}(x))[/itex]
[itex]= \phi_{h} \circ \phi_{g} (x) = \Phi(h) \circ \Phi(g)[/itex]
But the operation is reversed for this situation. So this is considered to be an antihomomorphism.
Any comments?