Hello,

I'm trying to find an example of any set S with a binary operation $\displaystyle \ast$ (meaning that it's closed) where there is a left identity that is NOT a right identity

So, for some $\displaystyle a,x \in S, $

$\displaystyle a \ast x = a$, but $\displaystyle x \ast a$ NOT $\displaystyle = a$

Thanks!