Changes by: Jason Hickey (jyh at cs.caltech.edu)
Date: 2006-03-20 09:44:55 -0800 (Mon, 20 Mar 2006)
Revision: 8944
Log message:

      Half-finished theorems for proving
      
         bind{'n; x. substl{'y; nth_prefix{'x; 'm}}} in BTerm
      
      The main theorem needs an extra lemma
         Itt_hoas_lof.normalize_mk_bterm_subst