MAYBE
Input TRS:
      1: d(a(x1)) -> b(d(x1))
      2: b(x1) -> a(a(a(x1)))
      3: c(d(c(x1))) -> a(d(x1))
      4: b(d(d(x1))) -> c(c(d(d(c(x1)))))
Number of strict rules: 4
Direct POLO(bPol) ... failed.
Uncurrying ... failed.
Dependency Pairs:
     #1: #c(d(c(x1))) -> #d(x1)
     #2: #d(a(x1)) -> #b(d(x1))
     #3: #d(a(x1)) -> #d(x1)
     #4: #b(d(d(x1))) -> #c(c(d(d(c(x1)))))
     #5: #b(d(d(x1))) -> #c(d(d(c(x1))))
     #6: #b(d(d(x1))) -> #d(d(c(x1)))
     #7: #b(d(d(x1))) -> #d(c(x1))
     #8: #b(d(d(x1))) -> #c(x1)
Number of SCCs: 1, DPs: 7
  SCC { #1..3 #5..8 }
POLO(Sum)... succeeded.
      a 	w: x1
      d 	w: x1 + 30613
      b 	w: x1
      c 	w: x1
      #d 	w: x1 + 30613
      #c 	w: x1
      #b 	w: x1
    USABLE RULES: { 1..4 }
    Removed DPs: #7 #8
Number of SCCs: 1, DPs: 5
  SCC { #1..3 #5 #6 }
POLO(Sum)... POLO(max)... QLPOS... POLO(mSum)... QWPOpS(mSum)... Mat2b... failed.
Finding a loop...  failed.