u_(k+1) = u_k +v_k +2p_k

v_(k+1) = 2u_k +v_k +2p_k

p_(k+1) = 3u_k +3v_k + p_k

where k indicates the time index. we wish to apply a four- dimensional data assimilation scheme to determine the vector x_0 at time t_0.

Suppose that we take observations of both u and p together at the two times t_0 and t_1. Determine whether we have enough information to reconstruct the vector x_0 uniquely.