MAYBE

Problem:
 active(app(nil(),YS)) -> mark(YS)
 active(app(cons(X,XS),YS)) -> mark(cons(X,app(XS,YS)))
 active(from(X)) -> mark(cons(X,from(s(X))))
 active(zWadr(nil(),YS)) -> mark(nil())
 active(zWadr(XS,nil())) -> mark(nil())
 active(zWadr(cons(X,XS),cons(Y,YS))) -> mark(cons(app(Y,cons(X,nil())),zWadr(XS,YS)))
 active(prefix(L)) -> mark(cons(nil(),zWadr(L,prefix(L))))
 mark(app(X1,X2)) -> active(app(mark(X1),mark(X2)))
 mark(nil()) -> active(nil())
 mark(cons(X1,X2)) -> active(cons(mark(X1),X2))
 mark(from(X)) -> active(from(mark(X)))
 mark(s(X)) -> active(s(mark(X)))
 mark(zWadr(X1,X2)) -> active(zWadr(mark(X1),mark(X2)))
 mark(prefix(X)) -> active(prefix(mark(X)))
 app(mark(X1),X2) -> app(X1,X2)
 app(X1,mark(X2)) -> app(X1,X2)
 app(active(X1),X2) -> app(X1,X2)
 app(X1,active(X2)) -> app(X1,X2)
 cons(mark(X1),X2) -> cons(X1,X2)
 cons(X1,mark(X2)) -> cons(X1,X2)
 cons(active(X1),X2) -> cons(X1,X2)
 cons(X1,active(X2)) -> cons(X1,X2)
 from(mark(X)) -> from(X)
 from(active(X)) -> from(X)
 s(mark(X)) -> s(X)
 s(active(X)) -> s(X)
 zWadr(mark(X1),X2) -> zWadr(X1,X2)
 zWadr(X1,mark(X2)) -> zWadr(X1,X2)
 zWadr(active(X1),X2) -> zWadr(X1,X2)
 zWadr(X1,active(X2)) -> zWadr(X1,X2)
 prefix(mark(X)) -> prefix(X)
 prefix(active(X)) -> prefix(X)

Proof:
 Open