YES(?,PRIMREC) We are left with following problem, upon which TcT provides the certificate YES(?,PRIMREC). Strict Trs: { +(0(), y) -> y , +(s(x), y) -> s(+(x, y)) , +(p(x), y) -> p(+(x, y)) , minus(0()) -> 0() , minus(s(x)) -> p(minus(x)) , minus(p(x)) -> s(minus(x)) , *(0(), y) -> 0() , *(s(x), y) -> +(*(x, y), y) , *(p(x), y) -> +(*(x, y), minus(y)) } Obligation: innermost runtime complexity Answer: YES(?,PRIMREC) The input was oriented with the instance of'multiset path order' as induced by the precedence + > s, + > p, + > minus, 0 > +, 0 > s, 0 > p, 0 > minus, minus > s, minus > p, * > +, * > s, * > p, * > minus, 0 ~ *, s ~ p . Hurray, we answered YES(?,PRIMREC)