YES
Input TRS:
      1: a(a(x1)) -> b(c(x1))
      2: b(b(x1)) -> c(d(x1))
      3: c(c(x1)) -> d(d(d(x1)))
      4: d(c(x1)) -> b(f(x1))
      5: d(d(d(x1))) -> a(c(x1))
      6: f(f(x1)) -> f(b(x1))
Number of strict rules: 6
Direct POLO(bPol) ... removes: 1 3 5
      a 	w: x1 + 27
      d 	w: x1 + 19
      b 	w: x1 + 24
      c 	w: x1 + 29
      f 	w: x1 + 24
Number of strict rules: 3
Direct POLO(bPol) ... failed.
Uncurrying ... failed.
Dependency Pairs:
     #1: #b(b(x1)) -> #d(x1)
     #2: #f(f(x1)) -> #f(b(x1))
     #3: #f(f(x1)) -> #b(x1)
     #4: #d(c(x1)) -> #b(f(x1))
     #5: #d(c(x1)) -> #f(x1)
Number of SCCs: 1, DPs: 3
  SCC { #1 #3 #5 }
POLO(Sum)... succeeded.
      a 	w: 0
      d 	w: 0
      b 	w: x1 + 1
      c 	w: x1 + 21239
      f 	w: x1 + 1
      #d 	w: x1
      #f 	w: x1
      #b 	w: x1
    USABLE RULES: { }
    Removed DPs: #1 #3 #5
Number of SCCs: 0, DPs: 0