MAYBE
Input TRS:
      1: top(ok(U(x,y))) -> top(check(D(x,y)))
      2: D(x,B()) -> U(x,B())
      3: F(x,U(O(y),z)) -> U(x,F(y,z))
      4: F(x,U(N(y),z)) -> U(x,F(y,z))
      5: D(O(x),F(y,z)) -> F(x,D(y,z))
      6: D(N(x),F(y,z)) -> F(x,D(y,z))
      7: F(x,U(E(),y)) -> U(x,F(E(),y))
      8: D(E(),F(x,y)) -> F(E(),D(x,y))
      9: U(O(x),y) ->= U(x,y)
      10: U(N(x),y) ->= U(x,y)
      11: D(O(x),y) ->= D(x,y)
      12: D(N(x),y) ->= D(x,y)
      13: E() ->= N(E())
      14: check(O(x)) ->= ok(O(x))
      15: check(U(x,y)) ->= U(check(x),y)
      16: check(U(x,y)) ->= U(x,check(y))
      17: check(D(x,y)) ->= D(check(x),y)
      18: check(D(x,y)) ->= D(x,check(y))
      19: check(F(x,y)) ->= F(check(x),y)
      20: check(F(x,y)) ->= F(x,check(y))
      21: check(O(x)) ->= O(check(x))
      22: check(N(x)) ->= N(check(x))
      23: U(ok(x),y) ->= ok(U(x,y))
      24: U(x,ok(y)) ->= ok(U(x,y))
      25: D(ok(x),y) ->= ok(D(x,y))
      26: D(x,ok(y)) ->= ok(D(x,y))
      27: F(ok(x),y) ->= ok(F(x,y))
      28: F(x,ok(y)) ->= ok(F(x,y))
      29: O(ok(x)) ->= ok(O(x))
      30: N(ok(x)) ->= ok(N(x))
Number of strict rules: 8
Direct POLO(bPol) ... removes: 3 5 11 9
      F 	w: x1 + 2 * x2 + 1
      top	w: x1 + 7582
      E 	w: 17067
      D 	w: x1 + 2 * x2 + 1
      O 	w: x1 + 31112
      B 	w: 1
      check	w: x1
      ok	w: x1
      N 	w: x1
      U 	w: x1 + 2 * x2 + 1
Number of strict rules: 6
Direct POLO(bPol) ... failed.
Uncurrying ... failed.
Dependency Pairs:
     #1: #D(N(x),F(y,z)) -> #F(x,D(y,z))
     #2: #D(N(x),F(y,z)) -> #D(y,z)
     #3: #D(N(x),y) ->? #D(x,y)
     #4: #D(ok(x),y) ->? #D(x,y)
     #5: #check(F(x,y)) ->? #F(x,check(y))
     #6: #check(F(x,y)) ->? #check(y)
     #7: #F(x,U(E(),y)) -> #F(E(),y)
     #8: #F(x,ok(y)) ->? #F(x,y)
     #9: #check(N(x)) ->? #check(x)
     #10: #F(ok(x),y) ->? #F(x,y)
     #11: #check(D(x,y)) ->? #D(check(x),y)
     #12: #check(D(x,y)) ->? #check(x)
     #13: #check(F(x,y)) ->? #F(check(x),y)
     #14: #check(F(x,y)) ->? #check(x)
     #15: #D(x,ok(y)) ->? #D(x,y)
     #16: #check(O(x)) ->? #check(x)
     #17: #check(U(x,y)) ->? #check(y)
     #18: #top(ok(U(x,y))) -> #top(check(D(x,y)))
     #19: #top(ok(U(x,y))) -> #check(D(x,y))
     #20: #top(ok(U(x,y))) -> #D(x,y)
     #21: #D(E(),F(x,y)) -> #F(E(),D(x,y))
     #22: #D(E(),F(x,y)) -> #D(x,y)
     #23: #check(U(x,y)) ->? #check(x)
     #24: #F(x,U(N(y),z)) -> #F(y,z)
     #25: #check(D(x,y)) ->? #D(x,check(y))
     #26: #check(D(x,y)) ->? #check(y)
Number of SCCs: 4, DPs: 18
  SCC { #18 }
POLO(Sum)... POLO(max)... QLPOS... POLO(mSum)... QWPOpS(mSum)... Mat2b... failed.
Finding a loop...  failed.