For thorough comparison, we implement discrete, neural and combined character-based models as well.
7 the character-based discrete model is a CRF tagging model using character unigrams, bigrams, trigrams and tag transitions (Tseng et al., 2005), and the character-based neural model exploits a bi-directional LSTM layer to model character sequences 8 and a CRF layer for  201495.2 97.2 Zhang et al.