Table 1 List of dependency features

Relationship term

Root of the portion of the dependency tree connecting phenotype and genotype

Stemmed relationship term

Stemmed by Mallet

Relative position of relationship term

Whether it is before the first entity, after the second entity or between them

The relationship term combined with the dependency relationship

To consider the grammatical role of the relationship term in the dependency path.

The relationship term and its relative position

Key term

Described in Ibn Faiz’s four step method [48]

Key term and its relative position

Collapsed version of the dependency path

All occurrences of nsubj/nsubjpass are replaced with subj, rcmod/partmod with mod, prep x with x and everything else with O, a placeholder to indicate that a dependency has been ignored.

Second version of the collapsed dependency path

Only the prep_* of dependency relationships are kept.

Negative dependency relationship

A binary feature that shows whether there is any node in the path between the entities which dominates a neg dependency relationship. This feature is used to catch the negative relationships.

prep_between

A binary feature that checks for the existence of two consecutive prep_between links in a dependency path.