- Datatype package now also supports arbitrarily branching datatypes
(using function types).
- Added new simplification procedure for proving distinctness of
constructors.
- dtK is now a reference.
consts ack :: "nat*nat => nat"
recdef ack "measure(%m. m) ** measure(%n. n)"
"ack(0,n) = Suc n"
"ack(Suc m,0) = ack(m, 1)"
"ack(Suc m,Suc n) = ack(m,ack(Suc m,n))"