MAYBE
Input TRS:
      1: a(b(a(x1))) -> b(c(x1))
      2: b(b(b(x1))) -> c(b(x1))
      3: c(x1) -> a(b(x1))
      4: c(d(x1)) -> d(c(b(a(x1))))
Number of strict rules: 4
Direct POLO(bPol) ... failed.
Uncurrying ... failed.
Dependency Pairs:
     #1: #b(b(b(x1))) -> #c(b(x1))
     #2: #c(x1) -> #a(b(x1))
     #3: #c(x1) -> #b(x1)
     #4: #a(b(a(x1))) -> #b(c(x1))
     #5: #a(b(a(x1))) -> #c(x1)
     #6: #c(d(x1)) -> #c(b(a(x1)))
     #7: #c(d(x1)) -> #b(a(x1))
     #8: #c(d(x1)) -> #a(x1)
Number of SCCs: 1, DPs: 8
  SCC { #1..8 }
POLO(Sum)... succeeded.
      a 	w: x1
      d 	w: x1 + 1
      b 	w: x1
      c 	w: x1
      #c 	w: x1
      #a 	w: x1
      #b 	w: x1
    USABLE RULES: { 1..4 }
    Removed DPs: #6..8
Number of SCCs: 1, DPs: 5
  SCC { #1..5 }
POLO(Sum)... succeeded.
      a 	w: x1 + 8366
      d 	w: 44083
      b 	w: x1 + 8366
      c 	w: x1 + 16732
      #c 	w: x1 + 8366
      #a 	w: x1
      #b 	w: x1
    USABLE RULES: { 1..4 }
    Removed DPs: #3 #5
Number of SCCs: 1, DPs: 3
  SCC { #1 #2 #4 }
POLO(Sum)... POLO(max)... QLPOS... POLO(mSum)... QWPOpS(mSum)... Mat2b... failed.
Finding a loop...  failed.