Natural Language Processing Named Entity Recognition A Survey on Deep Learning for Named Entity Recognition Relation Extraction More Data, More Relations, More Context and More Openness: A Review and Outlook for Relation Extraction Text Classification Deep Learning Based Text Classification: A Comprehensive Review Pre-trained Models Pre-trained Models for Natural Language Processing: A Survey A Survey on Contextual Embeddings Knowlege Graphs A Survey on Knowledge Graphs: Representation, Acquisition and Applications Knowledge Graphs