The question is:
Let A be a subset of Sn that contains all permutations alpha such that alpha can be written as a product of an even number of transpositions. Prove that A is a group with product of permutations.
I understand what I need to do to prove it, but I am not sure how to start it. Do I use:
Let alpha=(a1a2a3...an) and
beta=(b1b2b3...bn) and try to find closure,
or am I going about it the wrong way?