What is the interpretation of mt? The expected value of the hidden state at time t given the observations up to time t The expected value of the hidden state at time t given the observations up to time t - 1 The expected value of the observation at time t given the observations up to time t - 1 What is the interpretation of at? The expected value of the hidden state at time t given the observations up to time t The expected value of the hidden state at time t given the observations up to time t - 1 The expected value of the observation at time t given the observations up to time t - 1 What is the interpretation of ft? The expected value of the hidden state at time t given the observations up to time t The expected value of the hidden state at time t given the observations up to time t - 1 The expected value of the observation at time t given the observations up to time t - 1