Table 2 Rules for lexical feature generation
Rule name | Description |
|---|---|
Negation | Determine negation by checking existence of negative word e.g. a negative adjective modifying the verb or relation trigger, or a semantically negative word |
Tense (active/passive) | Tense determination |
Words in between entities | The sequence of words between the two entities |
Surface distance | Distance between the two recognized entities (including existing tokens and entity itself) |
Window left entity | A window of k words to the left of Entity 1, with their part-of-speech tags |
Window right entity | A window of k words to the right of Entity 2, with their part-of-speech tags |
Detect nominalization | Existence of nominalized verb located in left/right position of the entity and distance from specific entity |
Weak nominalization | Detect when an entity occurs after a preposition and whether a nominalized biomedical verb is located ahead of that preposition |