Definition:Ring of Square Matrices

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Let $R$ be a ring.

Let $n \in \Z_{>0}$ be a (strictly) positive integer.

Let $\map {\MM_R} n$ denote the $n \times n$ matrix space over $R$.

Let $+$ denote the operation of matrix entrywise addition.

Let $\times$ be (temporarily) used to denote the operation of conventional matrix multiplication.

The algebraic structure:

$\struct {\map {\MM_R} n, +, \times}$

is known as the ring of square matrices of order $n$ over $R$


When referring to the operation of matrix multiplication in the context of the ring of square matrices:

$\struct {\map {\MM_R} n, +, \times}$

we must have some symbol to represent it, and $\times$ does as well as any.

However, we do not use $\mathbf A \times \mathbf B$ for matrix multiplication $\mathbf A \mathbf B$, as it is understood to mean the vector cross product, which is something completely different.

Also see

  • Results about rings of square matrices can be found here.