Orð og tunga - 01.06.2012, Page 15

Mattliezv Wlielpton: From human-oriented dictionaries
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it are grouped in a synset. WordNet is sense-oriented; a traditional
dictionary is word-oriented.
Second, WordNet does not distinguish between polysemy and ho-
monymy. Polysemy is when a single word (lexeme) is associated with
more than one sense. The word shot would be a good example, as it
can express the sense associated with either Sentence (1) or Sentence
(2). Homonymy is when two different words (lexemes) happen to
have the same form: the classic example of this in English is the word-
form bank, which can refer either to the side of a river or to a particular
kind of financial institution. The intuition here is that the two senses
are completely unrelated and that it is no more than a historical co-
incidence that they are expressed by the same word-form. WordNet
remains completely agnostic on this distinction between polysemy
and homonymy because its basic building block is the sense, each
sense having one entry and being associated with a set of one or more
word-forms which can express that sense in a certain context, i.e. the
synset. It is the synset in WordNet which stands in sense-relations
to other synsets and we will now review some of the main relations
around which the database is structured.
2.3 Hyponymy-Hypernymy
Hyponymy is also known as the is_a relation, typically the subkind
relation. For instance, mare is a hyponym (Icelandic undirheiti; Greek:
hypo 'under' + onxjma 'name') of horse-, and conversely, horse is a hyper-
nym (Icelandic yfirheiti; Greek: hyper 'over' + onyma 'name') of mare,
because a mare is a (kind of) liorse. Hyponymy naturally creates hier-
archies:
(3) a mare is_a horse is_a mammal is_a animal
This is especially true of natural kinds, for which the hyponymy hier-
archy can become quite articulated.
According to the hierarchy in Figure 1, both mare and stallion are
hyponyms of horse, i.e. they are co-hyponyms; animal is the root of
this hierarchy. In fact, WordNet has a considerably more articulated
hierarchy than is shown here, with much greater depth. For instance,
stallion is in fact a co-hyponym with gelding: both are male horses but
the latter is castrated and the former not: this means that there is a
lexical gap in the hierarchy because there is no specialised lexeme in