MAYBE
Input TRS:
      1: b(d(b(x1))) -> c(d(b(x1)))
      2: b(a(c(x1))) -> b(c(x1))
      3: a(d(x1)) -> d(c(x1))
      4: b(b(b(x1))) -> a(b(c(x1)))
      5: d(c(x1)) -> b(d(x1))
      6: d(c(x1)) -> d(b(d(x1)))
      7: d(a(c(x1))) -> b(b(x1))
Number of strict rules: 7
Direct POLO(bPol) ... removes: 2
      a 	w: x1 + 26286
      d 	w: x1
      b 	w: x1 + 26286
      c 	w: x1 + 26286
Number of strict rules: 6
Direct POLO(bPol) ... failed.
Uncurrying ... failed.
Dependency Pairs:
     #1: #d(c(x1)) -> #d(b(d(x1)))
     #2: #d(c(x1)) -> #b(d(x1))
     #3: #d(c(x1)) -> #d(x1)
     #4: #d(a(c(x1))) -> #b(b(x1))
     #5: #d(a(c(x1))) -> #b(x1)
     #6: #d(c(x1)) -> #b(d(x1))
     #7: #d(c(x1)) -> #d(x1)
     #8: #a(d(x1)) -> #d(c(x1))
     #9: #b(b(b(x1))) -> #a(b(c(x1)))
     #10: #b(b(b(x1))) -> #b(c(x1))
Number of SCCs: 1, DPs: 3
  SCC { #1 #3 #7 }
POLO(Sum)... succeeded.
      a 	w: x1 + 1
      d 	w: x1
      b 	w: x1 + 1
      c 	w: x1 + 1
      #d 	w: x1
      #a 	w: 0
      #b 	w: 0
    USABLE RULES: { 1 3..7 }
    Removed DPs: #3 #7
Number of SCCs: 1, DPs: 1
  SCC { #1 }
POLO(Sum)... POLO(max)... QLPOS... POLO(mSum)... QWPOpS(mSum)... Mat2b... failed.
Finding a loop...  failed.