Before introducing this pronoun head model, we need to augment the set of entity-specific parameters, which currently contains only a distribution over heads (φ h Z ).
we add distributions φ t Z , φ g Z , and φ n Z over entity properties: φ t Z is a distribution over semantic types (PER, ORG, LOC, MISC), φ g Z over gender (MALE, FEMALE, EITHER, NEUTER), and φ n Z over number (SG, PL).