Are these REs equivalent? I have to implement a compiler for a given language as part of an assignment.
The language is kept simple enough such that it can be fully expressed through REs.
My question lies with two of the REs provided:

DIGIT := [0-9]?
INTEGER_LITERAL := DIGIT DIGIT*

When I saw the RE for INTEGER_LITERAL I sort of thought to myself:

&quot;Well that's just DIGIT+&quot;

Am I right to think so?
Any regular expression satisfies $r^+ = rr^* = r^*r$. In fact, one often defines $r^+$ using one of these formulas, usually $r^+ := rr^*$.