viterbi sequence-prediction pos-tags word2vec scikit-learn neural-networks conditional-random-fields NER word-embeddings syntactic-dependencies gensim fasttext evaluation_metrics document-classification classification SyntaxNet NLTK tokenization tf-idf stanford-NER relationship-extraction portuguese named-entity-recognition naive-bayes multi-label-classification maximum-entropy-markov-models logistic-regression language-models information-extraction imbalanced_data hyperparameter-optimization hidden-markov-models grid-search glove embeddings doc2vec dependency-graph deep-learning data-challenge convolutional-neural-networks conference character-language-models character-embeddings PyData LSTM KOVENS ELMo BERT