(+) :: Peano -> Peano -> Peano
-- testing 6 combinations of argument values
-- pruning with 0/0 rules
-- 3 candidates of size 1
-- 11 candidates of size 2
-- 38 candidates of size 3
-- 87 candidates of size 4
-- 218 candidates of size 5
-- tested 140 candidates
p + Z  =  p
p + S q  =  S p + q

(*) :: Peano -> Peano -> Peano
-- testing 7 combinations of argument values
-- pruning with 6/10 rules
-- 3 candidates of size 1
-- 11 candidates of size 2
-- 41 candidates of size 3
-- 108 candidates of size 4
-- 291 candidates of size 5
-- 746 candidates of size 6
-- tested 537 candidates
p * Z  =  Z
p * S q  =  p + p * q