Hi!
I've the next problem:
Be G a group with neuter e. Proof the next affirmation:
If is abelian
I tried to proof the equivalent:
If is not abelian
Proof:
I suppose that a^2 = e
a^2 = a . a = a . a^{-1} = a^{-1} . a = e\, \mbox{ ABSURDUM G is not abelian }
This proof not convinced me so I ask for your help.
Thank's