In this paper, we focus on the task of determining coreference relations as defined in MUC-6 (MUC-6 1995) and MUC-7 (MUC-7 1997).
a coreference relation denotes an identity of reference and holds between two textual elements known as markables, which can be definite noun phrases, demonstrative noun phrases, proper names, appositives, sub-noun phrases that act as modifiers, pronouns, and so on.