5,082 research outputs found
Distinguishing Word Senses in Untagged Text
This paper describes an experimental comparison of three unsupervised
learning algorithms that distinguish the sense of an ambiguous word in untagged
text. The methods described in this paper, McQuitty's similarity analysis,
Ward's minimum-variance method, and the EM algorithm, assign each instance of
an ambiguous word to a known sense definition based solely on the values of
automatically identifiable features in text. These methods and feature sets are
found to be more successful in disambiguating nouns rather than adjectives or
verbs. Overall, the most accurate of these procedures is McQuitty's similarity
analysis in combination with a high dimensional feature set.Comment: 11 pages, latex, uses aclap.st
Morphological Disambiguation by Voting Constraints
We present a constraint-based morphological disambiguation system in which
individual constraints vote on matching morphological parses, and
disambiguation of all the tokens in a sentence is performed at the end by
selecting parses that receive the highest votes. This constraint application
paradigm makes the outcome of the disambiguation independent of the rule
sequence, and hence relieves the rule developer from worrying about potentially
conflicting rule sequencing. Our results for disambiguating Turkish indicate
that using about 500 constraint rules and some additional simple statistics, we
can attain a recall of 95-96% and a precision of 94-95% with about 1.01 parses
per token. Our system is implemented in Prolog and we are currently
investigating an efficient implementation based on finite state transducers.Comment: 8 pages, Latex source. To appear in Proceedings of ACL/EACL'97
Compressed postscript also available as
ftp://ftp.cs.bilkent.edu.tr/pub/ko/acl97.ps.
Disambiguation of Super Parts of Speech (or Supertags): Almost Parsing
In a lexicalized grammar formalism such as Lexicalized Tree-Adjoining Grammar
(LTAG), each lexical item is associated with at least one elementary structure
(supertag) that localizes syntactic and semantic dependencies. Thus a parser
for a lexicalized grammar must search a large set of supertags to choose the
right ones to combine for the parse of the sentence. We present techniques for
disambiguating supertags using local information such as lexical preference and
local lexical dependencies. The similarity between LTAG and Dependency grammars
is exploited in the dependency model of supertag disambiguation. The
performance results for various models of supertag disambiguation such as
unigram, trigram and dependency-based models are presented.Comment: ps file. 8 page
Named Entity Extraction and Disambiguation: The Reinforcement Effect.
Named entity extraction and disambiguation have received much attention in recent years. Typical fields addressing these topics are information retrieval, natural language processing, and semantic web. Although these topics are highly dependent, almost no existing works examine this dependency. It is the aim of this paper to examine the dependency and show how one affects the other, and vice versa. We conducted experiments with a set of descriptions of holiday homes with the aim to extract and disambiguate toponyms as a representative example of named entities. We experimented with three approaches for disambiguation with the purpose to infer the country of the holiday home. We examined how the effectiveness of extraction influences the effectiveness of disambiguation, and reciprocally, how filtering out ambiguous names (an activity that depends on the disambiguation process) improves the effectiveness of extraction. Since this, in turn, may improve the effectiveness of disambiguation again, it shows that extraction and disambiguation may reinforce each other.\u
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