A regular grammar is a grammar where all of the production rules are of one of the
following forms:
where and represent any single non-terminal, and a represents any
single terminal, or the empty string.
If a grammar can only derive regular languages, but is not of the
above form, then (we claim) it can be converted to this form.
In order to justify our assertion that we can represent all regular
expressions in this manner, we give an algorithm for converting from
an FSA to a regular grammar.