YES(?,O(n^1))

Problem:
 a() -> g(c())
 g(a()) -> b()
 f(g(X),b()) -> f(a(),X)

Proof:
 RT Transformation Processor:
  strict:
   a() -> g(c())
   g(a()) -> b()
   f(g(X),b()) -> f(a(),X)
  weak:
   
  Matrix Interpretation Processor:
   dimension: 1
   interpretation:
    [f](x0, x1) = x0 + x1 + 12,
    
    [b] = 13,
    
    [g](x0) = x0 + 6,
    
    [c] = 28,
    
    [a] = 16
   orientation:
    a() = 16 >= 34 = g(c())
    
    g(a()) = 22 >= 13 = b()
    
    f(g(X),b()) = X + 31 >= X + 28 = f(a(),X)
   problem:
    strict:
     a() -> g(c())
    weak:
     g(a()) -> b()
     f(g(X),b()) -> f(a(),X)
   Matrix Interpretation Processor:
    dimension: 1
    interpretation:
     [f](x0, x1) = x0 + x1 + 31,
     
     [b] = 1,
     
     [g](x0) = x0,
     
     [c] = 0,
     
     [a] = 1
    orientation:
     a() = 1 >= 0 = g(c())
     
     g(a()) = 1 >= 1 = b()
     
     f(g(X),b()) = X + 32 >= X + 32 = f(a(),X)
    problem:
     strict:
      
     weak:
      a() -> g(c())
      g(a()) -> b()
      f(g(X),b()) -> f(a(),X)
    Qed