- #1
Bashyboy
- 1,421
- 5
Homework Statement
Suppose that ##G## is a cyclic group with generator ##g##, that ##H## is some arbitrary group, and that ##\phi : G \rightarrow H## is a homomorphism. Show that knowing ##\phi (g)### let's you compute ##\phi(g_1)## ##\forall g_1 \in G##
Homework Equations
##\phi(g^n) = \phi(\underbrace{g~\star_G~ g~ \star_G~ g ... \star_G~ g}_{n|}) = \underbrace{\phi (g) \star_H \phi(g) \star_H ... \star_H \phi(g)}_{|n|} = \phi(g)^n ##
The Attempt at a Solution
Let ##g_1 \in G## be arbitrary. This implies that ##\exists k \in \mathbb{Z}## such that ##g_1 = g^k##.
##\phi(g_1 \star_G g ) = \phi(g_1) \star_H \phi(g) \iff##
##\phi(g^k \star_G g) = \phi(g_1) \star_H \phi(g) \iff##
##\phi(g^{k+1}) = \phi(g_1) \star_H \phi(g) \iff##
##\phi(g)^{k+1} \star_H \phi(g)^{-1} = \phi(g_1) \iff##
##\phi(g)^k = \phi(g_1)##
This seems correct, but I am unsure. If this is correct, though, does this imply that ##H## is also cyclic, where ##\phi(g)## is the generator?