Abstract Algebra: We compute the automorphism group of A4, the alternating group on 4 letters. We have that Aut(G) = S4, the symmetric group on 4 letters, Inn(A4) = A4, and Out(A4)=Z/2. We note that the coset structure splits S4 into even and odd permutations.
U.Reddit course materials available at ureddit.com/class/23794/intro-to-group-theory Master list at mathdoctorbob.org/UReddit.html
Includes course on Group Theory (problems and solutions at website) and Ring Theory, and Field Theory. For Prerequisites on proofs and sets, see the Math Major Basics course.