Let $(S,\circ)$ be an algebra Let $x,y\in S.$ - $x+y$ is used instead of $x\circ y.$ - $e$ or $0$ is used for the [[Identity element of a binary operation|identity element]]. - $-x$ is used to denote the [[Inverse under a binary operation|inverse]] of $x$ under $\circ.$ - $nx$ is used to denote the $n$th [[Integer Power of Group Element|power]] of $x.$