Computes the alpha values in a linear-chain CRF.
crf_forward(inputs, state, transition_params, sequence_lengths)
| inputs | A [batch_size, num_tags] matrix of unary potentials. |
|---|---|
| state | A [batch_size, num_tags] matrix containing the previous alpha values. |
| transition_params | A [num_tags, num_tags] matrix of binary potentials. This matrix is expanded into a [1, num_tags, num_tags] in preparation for the broadcast summation occurring within the cell. |
| sequence_lengths | A [batch_size] vector of true sequence lengths. |
new_alphas: A [batch_size, num_tags] matrix containing the new alpha values.
See http://www.cs.columbia.edu/~mcollins/fb.pdf for reference.