Named Entity Types
In the expression named entity, the word named restricts the task to those entities for which one or many rigid designators, as defined by Kripke, stands for the referent. For instance, the automotive company created by Henry Ford in 1903 is referred to as Ford or Ford Motor Company. Rigid designators include proper names as well as certain natural kind terms like biological species and substances.
There is a general agreement to include temporal expressions and some numerical expressions (i.e., money, percentages, etc.) as instances of named entities in the context of the NER task. While some instances of these types are good examples of rigid designators (e.g., the year 2001) there are also many invalid ones (e.g., I take my vacations in “June”). In the first case, the year 2001 refers to the 2001st year of the Gregorian calendar. In the second case, the month June may refer to the month of an undefined year (past June, next June, June 2020, etc.). It is arguable that the named entity definition is loosened in such cases for practical reasons. The definition of the term named entity is therefore not strict and often has to be explained in the context it is used.
At least two hierarchies of named entity types have been proposed in the literature. BBN categories, proposed in 2002, is used for Question Answering and consists of 29 types and 64 subtypes. Sekine's extended hierarchy, proposed in 2002, is made of 200 subtypes.
Read more about this topic: Named-entity Recognition
Famous quotes containing the words named, entity and/or types:
“1946: I go to graduate school at Tulane in order to get distance from a “possessive” mother. I see a lot of a red-haired girl named Maude-Ellen. My mother asks one day: “Does Maude-Ellen have warts? Every girl I’ve known named Maude-Ellen has had warts.” Right: Maude-Ellen had warts.”
—Bill Bouke (20th century)
“What is this world of ours? A complex entity subject to sudden changes which all indicate a tendency to destruction; a swift succession of beings which follow one another, assert themselves and disappear; a fleeting symmetry; a momentary order.”
—Denis Diderot (1713–1784)
“Our children evaluate themselves based on the opinions we have of them. When we use harsh words, biting comments, and a sarcastic tone of voice, we plant the seeds of self-doubt in their developing minds.... Children who receive a steady diet of these types of messages end up feeling powerless, inadequate, and unimportant. They start to believe that they are bad, and that they can never do enough.”
—Stephanie Martson (20th century)