Viterbi Trellis

Viterbi trellis finds the most likely hidden-state path for the supplied W, D and R observations. Each column is one time step; highlighted links form the chosen path. Scores use logarithms, so longer sequences avoid probability underflow. In the weather model, state R emits W with probability 0.9 and state S emits D with probability 0.7; an impossible observation is reported instead of being assigned an artificial probability.