val demodulation: int -> environment -> equality -> equality -> int * equality
-val meta_convertibility: Cic.term -> Cic.term -> bool
-
val meta_convertibility_eq: equality -> equality -> bool
+val is_identity: environment -> equality -> bool
+
+val string_of_equality: ?env:environment -> equality -> string
+
+val subsumption: environment -> equality -> equality -> bool