# Structure Induced by Associative Operation is Associative

## Theorem

Let $\struct {T, \circ}$ be an algebraic structure, and let $S$ be a set.

Let $\struct {T^S, \oplus}$ be the structure on $T^S$ induced by $\circ$.

Let $\circ$ be associative.

Then the pointwise operation $\oplus$ induced on $T^S$ by $\circ$ is also associative.

## Proof

Let $f, g, h \in T^S$.

Let $\struct {T, \circ}$ be an associative algebraic structure.

Then:

 $\ds \map {\paren {\paren {f \oplus g} \oplus h} } x$ $=$ $\ds \map {\paren {f \oplus g} } x \circ \map h x$ Definition of Pointwise Operation $\ds$ $=$ $\ds \paren {\map f x \circ \map g x} \circ \map h x$ Definition of Pointwise Operation $\ds$ $=$ $\ds \map f x \circ \paren {\map g x \circ \map h x}$ $\circ$ is associative $\ds$ $=$ $\ds \map f x \circ \map {\paren {g \oplus h} } x$ Definition of Pointwise Operation $\ds$ $=$ $\ds \map {\paren {f \oplus \paren {g \oplus h} } } x$ Definition of Pointwise Operation

$\blacksquare$