In recent years, neural networks with distributed word representations (i.e., word embeddings) (Mikolov et al., 2013;Pennington et al., 2014) have been introduced to calculate word scores automatically for CRFs (Chiu and Nichols, 2016;.
for example, if a sentence x in NER task is "Barack Hussein Obama and Natasha Obama", we have the corresponding s = ((1, 3, P ER), (4, 4, O), (5, 6, P ER)) and y = (B-PER, I-PER, E-PER, O, B-PER, E-PER).