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