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,
Mentions are resolved as follows:
If no prior mention satisfies the given constraints, a new entity is created.
a common noun mention is resolved with the closest prior mention with the
same head, or with a head which is associated with the same concept or
a more specific concept in the concept hierarchy
a name mention is resolved with the closest prior mention with the same
name, or a superstring of the current name (so that, for example, "Bush"
will be resolved with "George Bush")
a third-person pronoun mention ("he", "she", "it", "they", "him", "her",
"them") will be resolved with the closest prior mention which agrees with
the pronoun in number and human-ness (antecedents of "he", "she", "him",
and "her" must be human; antecedents of "it" must not be human).
Human-ness for nouns is based on the human feature in the predicate-argument
structure; for names, person names are considered human, while
other names are considered non-human. This classification is slightly
incorrect since the dictionary labels an entry as human if any sense (not
necessarily the most common sense) of that entry is human.
a first- or second- person pronoun is resolved with the closest prior mention
of the same pronoun
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.