Table of Contents - 11.2.4. Matrices of dimension 0 and 1

As already mentioned before, and shown in mat0dimbas0, the empty set is
the sole zero-dimensional matrix (also called "empty matrix", see Wikipedia
https://en.wikipedia.org/wiki/Matrix_(mathematics)#Empty_matrices). In the
following, some properties of the empty matrix are shown, especially that the
empty matrix over an arbitrary ring forms a commutative ring, see
mat0dimcrng.

For the one-dimensional case, it can be shown that a ring of matrices with
dimension 1 is isomorphic to the underlying ring, see mat1ric.