 is a set of sentences with the
| same consequences as T.  Clearly, T is a set of axioms of T, and
| the empty set is a set of axioms of T if and only if T is a set
| of valid sentences of $L$.  Every set of sentences !S! is a set
| of axioms for the closed theory T = {p : !S! |= p}.  A theory T
| is 'finitely axiomatizable' iff it has a finite set of axioms.
|
| The most convenient and standard way of giving a theory T is by
| listing a finite or infinite set of axioms for it.  Another way
| to give a theo