As many previous studies report, an ideal headline must have from 8 to 10 tokens (Banko et al., 2000).
we include three binary features that correspond to the following conditions: (1) if the headline length so far is less than or equal to seven; (2) if the headline length so far is greater than or equal to 11; (3) if the token under analysis is assigned to the headline, which is a bias feature.