Structure Induced by Ring with Unity Operations is Ring with Unity
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Theorem
Let $\struct {R, +, \circ}$ be a ring with unity whose unity is $1_R$.
Let $S$ be a set.
Let $\struct {R^S, +', \circ'}$ be the structure on $R^S$ induced by $+'$ and $\circ'$.
Then $\struct {R^S, +', \circ'}$ is a ring with unity whose unity is $f_{1_R}: S \to R$, defined by:
- $\forall s \in S: \map {f_{1_R} } s = 1_R$
Proof
By Structure Induced by Ring Operations is Ring then $\struct {R^S, +', \circ'}$ is a ring.
We have from Induced Structure Identity that the constant mapping $f_{1_R}: S \to R$ defined as:
- $\forall x \in S: \map {f_{1_R} } x = 1_R$
is the identity for $\struct {R^S, \circ'}$.
The result follows by definition of ring with unity and unity of ring.
$\blacksquare$