Talk:Transpose of Matrix Product

In the last step, are we assuming $\circ$ is commutative? If yes, how do we know? If not, how did we prove the theorem? --GFauxPas 19:43, 23 February 2012 (EST)
 * Good call, I'd never noticed that. I have restricted our theorem to apply exactly that condition. This becomes important in the study of Lie groups (which I keep promising myself I'm going to try to get my head round). --prime mover 02:10, 24 February 2012 (EST)