Evaluate subexpressions built up from integer literals of type :int, by
proof.
DESCRIPTION
When applied to a term, INT_REDUCE_CONV performs a recursive bottom-up
evaluation by proof of subterms built from integer literals of type :int
using the unary operators `--', `inv' and `abs', and the binary
arithmetic (`+', `-', `*', `/', `pow') and relational (`<', `<=',
`>', `>=', `=') operators, as well as propagating literals through
logical operations, e.g. T /\ x <=> x, returning a theorem that the original
and reduced terms are equal. The permissible integer literals are of the form
&n or -- &n for numeral n, nonzero in the negative case.
The corresponding INT_REDUCE_CONV works for the type of integers. The more
general function REAL_RAT_REDUCE_CONV works similarly over :int but for
arbitrary rational literals.