MAYBE
Input TRS:
      1: a(b(c(x1))) -> c(b(a(x1)))
      2: a(c(x1)) -> a(a(d(a(x1))))
      3: d(a(b(x1))) -> b(a(d(x1)))
      4: d(a(c(x1))) -> b(c(c(x1)))
Number of strict rules: 4
Direct POLO(bPol) ... failed.
Uncurrying ... failed.
Dependency Pairs:
     #1: #a(c(x1)) -> #a(a(d(a(x1))))
     #2: #a(c(x1)) -> #a(d(a(x1)))
     #3: #a(c(x1)) -> #d(a(x1))
     #4: #a(c(x1)) -> #a(x1)
     #5: #d(a(b(x1))) -> #a(d(x1))
     #6: #d(a(b(x1))) -> #d(x1)
     #7: #a(b(c(x1))) -> #a(x1)
Number of SCCs: 1, DPs: 7
  SCC { #1..7 }
POLO(Sum)... succeeded.
      a 	w: x1
      d 	w: x1 + 8856
      b 	w: x1
      c 	w: x1 + 8856
      #d 	w: x1 + 8856
      #a 	w: x1
    USABLE RULES: { 1..4 }
    Removed DPs: #4 #7
Number of SCCs: 2, DPs: 2
  SCC { #6 }
POLO(Sum)... POLO(max)... succeeded.
      a 	w: x1
      d 	w: 0
      b 	w: x1 + 1
      c 	w: 0
      #d 	w: x1
      #a 	w: 0
    USABLE RULES: { }
    Removed DPs: #6
Number of SCCs: 1, DPs: 1
  SCC { #1 }
POLO(Sum)... POLO(max)... QLPOS... POLO(mSum)... QWPOpS(mSum)... Mat2b... failed.
Finding a loop...  failed.