MAYBE

Problem:
 0(1(2(3(x1)))) -> 1(4(3(x1)))
 1(2(0(4(2(x1))))) -> 3(4(5(4(x1))))
 3(3(0(3(2(x1))))) -> 3(2(4(1(x1))))
 5(2(1(0(4(x1))))) -> 5(5(4(5(x1))))
 0(1(4(5(0(5(x1)))))) -> 3(0(4(0(3(5(x1))))))
 0(2(5(2(1(5(x1)))))) -> 5(2(1(5(4(x1)))))
 0(3(5(1(5(5(x1)))))) -> 0(5(1(5(4(x1)))))
 2(2(5(1(4(5(4(3(x1)))))))) -> 2(2(3(3(0(1(0(3(x1))))))))
 0(0(0(2(4(1(2(2(4(x1))))))))) -> 0(0(0(4(3(3(4(4(x1))))))))
 2(4(4(3(4(2(0(3(2(x1))))))))) -> 3(4(3(4(1(3(3(1(x1))))))))
 0(1(4(3(2(3(2(3(5(3(x1)))))))))) -> 1(4(3(0(3(4(2(5(3(x1)))))))))
 0(2(1(5(0(4(3(1(4(2(2(x1))))))))))) -> 0(0(4(0(5(1(0(5(4(4(2(x1)))))))))))
 4(4(3(3(0(2(4(2(4(4(1(5(x1)))))))))))) -> 4(4(0(4(3(1(5(5(5(2(5(x1)))))))))))
 5(3(0(0(5(5(2(0(2(2(3(3(x1)))))))))))) -> 5(5(4(1(5(2(0(5(2(4(3(x1)))))))))))
 0(2(0(2(5(5(1(5(0(2(5(2(2(x1))))))))))))) -> 5(4(3(1(4(0(1(0(1(5(2(x1)))))))))))
 0(3(1(4(4(2(0(5(4(0(1(0(4(x1))))))))))))) -> 0(0(4(4(1(0(4(0(0(2(2(4(4(x1)))))))))))))
 1(2(4(1(1(0(2(5(3(4(0(1(4(0(3(x1))))))))))))))) -> 1(1(0(4(5(0(3(2(0(5(2(0(0(3(3(x1)))))))))))))))
 2(3(5(2(4(4(5(1(4(4(4(1(3(2(3(x1))))))))))))))) -> 2(3(3(1(1(1(5(3(3(5(1(3(5(2(3(x1)))))))))))))))
 5(4(2(5(2(5(3(2(3(3(1(5(0(0(5(x1))))))))))))))) -> 5(2(3(5(4(1(3(1(4(4(4(4(1(3(5(x1)))))))))))))))
 0(0(2(4(1(2(2(1(3(2(0(4(5(5(4(2(x1)))))))))))))))) ->
 0(5(1(1(0(2(3(5(4(3(0(2(5(2(3(5(1(x1)))))))))))))))))
 0(1(1(5(3(0(1(4(2(2(4(0(1(0(2(3(4(x1))))))))))))))))) ->
 0(4(2(2(0(1(5(4(4(0(2(2(2(5(5(4(x1))))))))))))))))
 0(2(3(2(5(2(4(3(2(4(3(0(2(4(5(1(3(x1))))))))))))))))) ->
 3(4(3(5(2(5(3(1(5(0(1(0(5(5(2(3(x1))))))))))))))))
 4(5(4(5(4(2(1(4(5(0(2(0(4(3(0(0(1(0(0(2(x1)))))))))))))))))))) ->
 4(4(2(2(5(2(0(0(0(5(3(4(1(2(2(1(1(5(0(0(x1))))))))))))))))))))
 3(0(1(0(5(2(4(4(4(5(2(4(1(1(4(5(4(0(3(2(1(x1))))))))))))))))))))) ->
 3(4(2(0(4(5(2(2(2(3(3(3(5(0(5(5(3(2(1(1(4(x1)))))))))))))))))))))
 3(3(2(1(0(0(3(1(2(0(2(1(2(3(5(4(0(2(2(1(1(x1))))))))))))))))))))) ->
 3(4(5(2(4(3(4(3(5(3(4(5(4(2(5(5(1(0(1(x1)))))))))))))))))))

Proof:
 Open