Changes by: Aleksey Nogin (nogin at cs.caltech.edu)
Date: 2000-05-14 17:13:34 -0700 (Sun, 14 May 2000)
Revision: 2971
Log message:
Use StringSet for unification constants instead of string list.
Converted Term_ds to use String_set.StringSet instead of
its private copy of StringSet.
2% speedup on TPTP's GEN.