Reference Resolution

The Jet reference resolver resolves anaphoric references to noun phrases.  It is intended to be invoked as the last step in processing each sentence in a document.

The input to reference resolution consists of a set of annotations of type constit with type=ngroup.  These are called the 'mentions'.   Each such annotation should have a pa feature giving its predicate-argument structure, and -- if its head is a name -- the feature isName with some non-null value.

The output of reference resolution is a set of annotations of type entity.  Each entity annotation corresponds to a set of one or more mentions which are deemed to be coreferential.  The entity annotation has the features head, position, mentions, number, name, and human.

Mentions are resolved as follows:

If no prior mention satisfies the given constraints, a new entity is created.

In addition, after mentions are resolved, reference resolution searches for annotations of type event.  For each event, it generates an annotation of type r-event which is identical except that any feature whose value is a mention (ngroup) is replaced by the entity to which the mention was resolved.