Talk:Product of group subsets

„It will be a subgroup if and only if ST = TS and the two subgroups are said to permute. In this case ST is the group generated by S and T, i.e. ST = TS = < S ∪ T >. If either S or T is normal then this condition is satisfied and ST is a subgroup“ This is wrong: if ST is a subgroup, then it doesn't necessarily follows that ST = TS. Also if S or T are normal, then they don't necessarily commute. Please clarify! 129.69.116.157 (talk) 10:32, 29 July 2014 (UTC)[reply]

You are wrong on both counts. I have added some inline citations for both statements. 86.127.138.67 (talk) 17:49, 2 April 2015 (UTC)[reply]