Suppose that we are at the word "them" and the hypothesis we are expanding is correct.
we have correctly identified "Bill Clinton" with entity type "person" and mention type "name;" that we have identified "the Senate" with entity type "organization" and mention type "name;" and that we have identified both "The President" and "his" as entities with entity type "person" and mention types "nominal" and "pronoun," respectively, and that "The President" points back to the chain Bill Clinton and that "his" points back to the chain Bill Clinton, The President .