1. A computer-implemented method comprising: computing a semantic hash for an entity having an entity identifier (ID); upon the occurrence of an entity milestone, changing the entity ID; computing a semantic hash for the entity having the changed entity ID; maintaining history information comprising entity IDs and semantic hashes associated with the entity over a period of time that includes a plurality of entity milestones; and periodically removing at least one set of older entities and retaining entity IDs and semantic hashes associated with the removed entities.
1. A computer-implemented method comprising: computing a semantic hash for an entity having an entity identifier (ID); upon the occurrence of an entity milestone, changing the entity ID; computing a semantic hash for the entity having the changed entity ID; maintaining history information comprising entity IDs and semantic hashes associated with the entity over a period of time that includes a plurality of entity milestones; and periodically removing at least one set of older entities and retaining entity IDs and semantic hashes associated with the removed entities. 4. The computer-implemented method of claim 1 , wherein an event milestone comprises removal of entities from a coreference set.