MAYBE
MAYBE
TRS:
 {
                  mark(__(X1, X2)) -> active(__(mark(X1), mark(X2))),
                       mark(nil()) -> active(nil()),
                      mark(U12(X)) -> active(U12(mark(X))),
                        mark(tt()) -> active(tt()),
                      mark(U11(X)) -> active(U11(mark(X))),
                  mark(isNePal(X)) -> active(isNePal(mark(X))),
                  __(X1, mark(X2)) -> __(X1, X2),
                __(X1, active(X2)) -> __(X1, X2),
                  __(mark(X1), X2) -> __(X1, X2),
                __(active(X1), X2) -> __(X1, X2),
              active(__(X, nil())) -> mark(X),
           active(__(__(X, Y), Z)) -> mark(__(X, __(Y, Z))),
              active(__(nil(), X)) -> mark(X),
                 active(U12(tt())) -> mark(tt()),
                 active(U11(tt())) -> mark(U12(tt())),
  active(isNePal(__(I, __(P, I)))) -> mark(U11(tt())),
                      U12(mark(X)) -> U12(X),
                    U12(active(X)) -> U12(X),
                      U11(mark(X)) -> U11(X),
                    U11(active(X)) -> U11(X),
                  isNePal(mark(X)) -> isNePal(X),
                isNePal(active(X)) -> isNePal(X)
 }
 DUP: We consider a non-duplicating system.
  Trs:
   {
                    mark(__(X1, X2)) -> active(__(mark(X1), mark(X2))),
                         mark(nil()) -> active(nil()),
                        mark(U12(X)) -> active(U12(mark(X))),
                          mark(tt()) -> active(tt()),
                        mark(U11(X)) -> active(U11(mark(X))),
                    mark(isNePal(X)) -> active(isNePal(mark(X))),
                    __(X1, mark(X2)) -> __(X1, X2),
                  __(X1, active(X2)) -> __(X1, X2),
                    __(mark(X1), X2) -> __(X1, X2),
                  __(active(X1), X2) -> __(X1, X2),
                active(__(X, nil())) -> mark(X),
             active(__(__(X, Y), Z)) -> mark(__(X, __(Y, Z))),
                active(__(nil(), X)) -> mark(X),
                   active(U12(tt())) -> mark(tt()),
                   active(U11(tt())) -> mark(U12(tt())),
    active(isNePal(__(I, __(P, I)))) -> mark(U11(tt())),
                        U12(mark(X)) -> U12(X),
                      U12(active(X)) -> U12(X),
                        U11(mark(X)) -> U11(X),
                      U11(active(X)) -> U11(X),
                    isNePal(mark(X)) -> isNePal(X),
                  isNePal(active(X)) -> isNePal(X)
   }
  Fail