Testing
Given a commutative ring $A$. A pair $(M, \mu)$ consists of abelian group $M$ and operator $\mu$ such that
$$\mu : X \times M \to M \quad (x,m) \mapsto \mu(x,m) := m \cdot x$$
is said to be an $A$-module if it satisfies certain rule.
Testing
Given a commutative ring $A$. A pair $(M, \mu)$ consists of abelian group $M$ and operator $\mu$ such that
$$\mu : X \times M \to M \quad (x,m) \mapsto \mu(x,m) := m \cdot x$$
is said to be an $A$-module if it satisfies certain rule.