Implemented "ordered rewriting": rules which merely permute variables, such
as commutativity, are only applied if the term becaomes lexicographically
smaller (according to some fixed ordering on the term structure).
(*Dummy theory to document dependencies *)
Datatype = "constructor" + "inductive" + "coinductive" + Univ + QUniv
(*this must be capital to avoid conflicts with ML's "datatype" *)