- Moved abs_def to drule.ML
- elim_defs now takes a boolean argument which controls the automatic
expansion of theorems mentioning constants whose definitions are
eliminated
consts norm :: ifex => ifex
primrec
"norm (CIF b) = CIF b"
"norm (VIF x) = VIF x"
"norm (IF b t e) = normif b (norm t) (norm e)"