YES(?,PRIMREC)

We are left with following problem, upon which TcT provides the
certificate YES(?,PRIMREC).

Strict Trs:
  { rev(a()) -> a()
  , rev(b()) -> b()
  , rev(++(x, x)) -> rev(x)
  , rev(++(x, y)) -> ++(rev(y), rev(x)) }
Obligation:
  innermost runtime complexity
Answer:
  YES(?,PRIMREC)

The input was oriented with the instance of'multiset path order' as
induced by the precedence

 rev > b, rev > ++, a > b, a > ++, ++ > b, rev ~ a .

Hurray, we answered YES(?,PRIMREC)