YES(?,PRIMREC)

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

Strict Trs:
  { a__c() -> a__f(g(c()))
  , a__c() -> c()
  , a__f(X) -> f(X)
  , a__f(g(X)) -> g(X)
  , mark(g(X)) -> g(X)
  , mark(c()) -> a__c()
  , mark(f(X)) -> a__f(X) }
Obligation:
  innermost runtime complexity
Answer:
  YES(?,PRIMREC)

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

 a__c > a__f, a__c > g, a__c > c, a__c > f, a__f > f, g > f, c > f,
 mark > a__f, mark > g, mark > c, mark > f, a__c ~ mark, a__f ~ g,
 a__f ~ c, g ~ c .

Hurray, we answered YES(?,PRIMREC)