Then we define the weight matrix representing the coreferential relation as: if m i and m j are coreferential, and c i = c j 0 Otherwise Ensuring topical coherence (Principle 3) has been beneficial for wikification on formal texts (e.g., News) by linking a set of semantically-related mentions to a set of semantically-related concepts simultaneously Ratinov et al., 2011;Cheng and Roth, 2013).
the shortness of a single tweet means that it may not provide enough topical clues.