meta closed. Why is it necessary, anyway?
~subst metasenv));
if t1 === t2 then
metasenv, subst
+(* CSC: To speed up Oliboni's stuff. Why is it necessary, anyway?
+ else if
+ NCicUntrusted.metas_of_term subst context t1 = [] &&
+ NCicUntrusted.metas_of_term subst context t2 = []
+ then
+ if NCicReduction.are_convertible ~metasenv ~subst context t1 t2 then
+ metasenv,subst
+ else
+ raise (UnificationFailure (lazy "Closed terms not convertible"))
+*)
else
match (t1,t2) with
| C.Appl [_], _ | _, C.Appl [_] | C.Appl [], _ | _, C.Appl []