Table 1.

Summary of knowledge-based approaches and the resulting improvements for each problem domain.

Problem Domain	Use of Knowledge/Knowledge bases	Nature of Improvement
Emoji Similarity and Sense Disambiguation	Generation and application of EmojiNet	Leveraging linguistic knowledge for emoji interpretation
Implicit Entity Linking	Adapted UMLS definitions for identifying medical entities, and Wikipedia and Twitter data for identifying Twitter entities	Recall and coverage
Understanding Drug Abuse-related Discussions	Application of Drug Abuse Ontology along with slang term dictionaries and grammar	Recall and coverage
Traffic Data Analysis	Statistical knowledge extraction and using ontologies for Twitter event extraction	Anomaly detection and explanation; Multi-modal data stream correlation