YES(?,PRIMREC)

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

Strict Trs:
  { app(nil(), YS) -> YS
  , app(cons(X), YS) -> cons(X)
  , from(X) -> cons(X)
  , zWadr(XS, nil()) -> nil()
  , zWadr(nil(), YS) -> nil()
  , zWadr(cons(X), cons(Y)) -> cons(app(Y, cons(X)))
  , prefix(L) -> cons(nil()) }
Obligation:
  innermost runtime complexity
Answer:
  YES(?,PRIMREC)

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

 nil > app, nil > cons, from > app, from > cons, zWadr > app,
 zWadr > cons, prefix > app, prefix > cons, nil ~ from, nil ~ zWadr,
 nil ~ prefix, from ~ zWadr, from ~ prefix, zWadr ~ prefix .

Hurray, we answered YES(?,PRIMREC)