The PVS prelude.
The prelude consists of theories that are built in to the PVS system.
It is typechecked the same as any other PVS theory, but there are hooks
in the typechecker that require most of these theories to be available,
hence the order of the theories is important. For example, no formulas
may be declared before the booleans are available, as the formula is
expected to have type bool. Since definitions implicitly involve both
formulas and equality, the booleans theory may not include any
definitions. Formulas are given below as AXIOMs, POSTULATEs, and LEMMAs.
POSTULATEs are formulas that can be proved using the decision procedures,
but would have to be given as axioms in a pure development of the theory.
AXIOMs are formulas that cannot be proved, and LEMMAS are formulas that
have been proved.