YES
Input TRS:
      1: a(x1) -> b(b(x1))
      2: b(b(b(x1))) -> a(x1)
Number of strict rules: 2
Direct POLO(bPol) ... removes: 1 2
      a 	w: x1 + 5
      b 	w: x1 + 2
Number of strict rules: 0