(related to Definition: Associativity)
Let $(X,\ast)$ be an algebraic structure with an associative binary operation \(\ast\). When we repeatedly apply the operation on a finite number of elements of $X$, the result does not depend on the way we put the parantheses. In other words, we can also omitt the parantheses:
\[x_1\ast x_2\ast x_3\ast \ldots\ast x_n:=(\ldots((x_1\ast x_2)\ast x_3)\ast \ldots)\ast x_n\]
Proofs: 1