MAYBE
Input TRS:
      1: b(c(x1)) -> d(c(x1))
      2: b(d(x1)) -> d(b(x1))
      3: a(d(x1)) -> a(b(b(x1)))
Number of strict rules: 3
Direct POLO(bPol) ... failed.
Uncurrying ... failed.
Dependency Pairs:
     #1: #b(d(x1)) -> #b(x1)
     #2: #a(d(x1)) -> #a(b(b(x1)))
     #3: #a(d(x1)) -> #b(b(x1))
     #4: #a(d(x1)) -> #b(x1)
Number of SCCs: 2, DPs: 2
  SCC { #1 }
POLO(Sum)... succeeded.
      a 	w: 0
      d 	w: x1 + 1
      b 	w: 0
      c 	w: 0
      #a 	w: 0
      #b 	w: x1
    USABLE RULES: { }
    Removed DPs: #1
Number of SCCs: 1, DPs: 1
  SCC { #2 }
POLO(Sum)... POLO(max)... QLPOS... POLO(mSum)... QWPOpS(mSum)... Mat2b... failed.
Finding a loop...  failed.