We are left with following problem, upon which TcT provides the
certificate YES(?,O(n^1)).

Strict Trs:
  { list(Cons(x, xs)) -> list(xs)
  , list(Nil()) -> True()
  , list(Nil()) -> isEmpty[Match](Nil())
  , notEmpty(Cons(x, xs)) -> True()
  , notEmpty(Nil()) -> False()
  , goal(x) -> list(x) }
Obligation:
  innermost runtime complexity
Answer:
  YES(?,O(n^1))

The input was oriented with the instance of 'Small Polynomial Path
Order (PS,1-bounded)' as induced by the safe mapping

 safe(list) = {}, safe(Cons) = {1, 2}, safe(Nil) = {},
 safe(True) = {}, safe(isEmpty[Match]) = {1}, safe(notEmpty) = {},
 safe(False) = {}, safe(goal) = {}

and precedence

 goal > list .

Following symbols are considered recursive:

 {list}

The recursion depth is 1.

For your convenience, here are the satisfied ordering constraints:

      list(Cons(; x,  xs);) > list(xs;)              
                                                     
               list(Nil();) > True()                 
                                                     
               list(Nil();) > isEmpty[Match](; Nil())
                                                     
  notEmpty(Cons(; x,  xs);) > True()                 
                                                     
           notEmpty(Nil();) > False()                
                                                     
                   goal(x;) > list(x;)               
                                                     

Hurray, we answered YES(?,O(n^1))