YES

Problem:
 0(x1) -> 1(x1)
 4(5(4(5(x1)))) -> 4(4(5(5(x1))))
 5(5(5(5(5(5(4(4(4(4(4(4(x1)))))))))))) -> 2(x1)

Proof:
 KBO Processor:
  weight function:
   w0 = 1
   w(4) = w(5) = w(1) = w(0) = 1
   w(2) = 0
  precedence:
   2 > 0 > 1 > 5 > 4
  problem:
   
  Qed