disambiguation of homographic adjective and adverb forms in croatian texts danijela merkler*, daša...
TRANSCRIPT
Disambiguation of homographic adjective and adverb forms in
Croatian texts
Danijela Merkler*, Daša Berović*, Željko Agić**
* Department of Linguistics** Department of Information Sciences
Faculty of Humanities and Social Sciences, University of Zagreb
[email protected]; [email protected]; [email protected]
NooJ 2011Dubrovnik
2011-06-15
Talk overview project ACCURAT problem and corpora modeling local grammars and applying them statistical evaluation
NooJ2011Dubrovnik2011-06-15
ACCURAT FP7 project main goal - to develop methods and techniques
to overcome one of the central problems of machine translation – the lack of linguistic resources for under-resourced areas of machine translation
key innovation - creation of methodology and tools to measure, to find and to use comparable corpora to improve the quality of MT
the ACCURAT project will significantly contribute not only to the theory of MT, but also to corpus linguistics, information extraction and natural language processing in general
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Scientific objectives create comparability metrics – to develop the
methodology and determine criteria to measure the comparability of source and target language documents in comparable corpora
establish research methods for alignment and extraction of lexical, terminological and other linguistic data from comparable corpora
disambiguation – important process for POS and MSD tagging
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Problem parallel and comparable resources are sparse for Croatian
when paired with any of the languages included in the project, especially if the other language is under-resourced as well
importance of high quality annotation for existing language resources for Croatian building (factored) language models for MT using text anchors in comparable resources
MSD-tagging and lemmatization errors detected in existing Croatian language resources e.g. Croatian National Corpus v2.5 (automatically lemmatized
and MSD-tagged), manually annotated subcorpora, Croatian Dependency Treebank
manual analysis of their annotation reveals regular patterns in these errors
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Problem forms of descriptive adjectives in the nominative singular
case in the neuter gender are the same as the forms of the adverbs that are made from those adjectives by suffixation
these adverbs are realized in context in most cases adverb is made from adjective that has
abstract meaning there are several types of word forms
the forms of adverbs and adjectives that occur with no semantic constraints: razdragano (gleeful), bahato (arrogant), ubrzano (rapidly), uzrujano (upset), umiljato (cuddly)
forms that are made from verbs: drhtavo (shaking), laskavo (flattering), šepavo (lame)
forms that have dual meaning (concrete and abstract): mlako (lukewarm), šugavo (itchy), mračno (darkly), hladno (cold), gorko (bitter)
forms that denote spatial and temporal relations: rano (early), duboko (deeply), plitko (shallow), lijevo (left)
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Corpora Croatia Weekly
100 kw newspaper corpus (newspaper published from 1998 to 2000, 118 numbers)
it covers different domains: politics, economy and finance, tourism, ecology, culture, art, sports
part of Croatian side of the Croatian-English Parallel Corpus manually lemmatized and MSD-tagged using the MULTEXT-East v3 morphosyntactic specifications
1984. Orwell’s "1984" corpus, manually lemmatized and
MSD-tagged using MULTEXT-East v4 languages: En, Ro, Sl, Cs, Et, Hu, Sr, Bg, Ru, Mk,
Hr... encoded in TEI P4 (XML)
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Corpora imported the corpora to NooJ
used the NooJ XML import feature kept the MSD feature annotations for adjectives,
adverbs, nouns and verbs converted the annotations for these PoS from
Multext-East to NooJ format for lexical resources modified feature annotations
e.g. MTE verb type from auxiliary, copulative to PG (auxiliary verb) in NooJ
preprocessing enabled designing the rules without using Croatian resources for NooJ, i.e. skipping NooJ linguistic analysis
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Patterns we noticed several types of patterns in which
adverbs that are homographic with adjectives occur
they are defined by their contextual environment
1) Vpg + A* + V → Vpg + R* + V
2) Vpg + A + A* → Vpg + R + A*
3) A* + V → R* + V
4) A + A* + N → R + A* + N
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Vpg + A* + V
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Vpg + A + A*
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A* + V
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A + A* + N
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Statistics 1
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manually checked concordances
errors frequently include the word sve, so we upgraded all grammars in order not to recognize sve
cw100 orwellcw100 + orwell
Vpg + A* + V 64 % 62 % 63 %
Vpg + A + A* 100 % 100 % 100 %
A* + V 82 % 54 % 67 %
A + A* + N 69 % 75 % 70 %
total 77 % 61 % 70 %
Example of upgraded grammar
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Statistics 2
obtained results improved after we applied new grammars
significant difference between newspaper and literature corpus
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cw100 orwellcw100 + orwell
Vpg + A* + V 100 % 83 % 92 %
Vpg + A + A* 100 % 100 % 100 %
A* + V 87 % 63 % 74 %
A + A* + N 78 % 100 % 82 %
total 89 % 73 % 83 %
Future work forms of relational adjectives in the nominative
singular case in the masculine gender are the same as the forms of the adverbs that are made from those adjectives by suffixation (junački, pučki, bratski, životinjski)
disambiguation of these forms also depends on the grammatical context in which they occur, so it can also be done in a similar way
applying the disambiguation rules to other Croatian language resources
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Thank you for your attention.
The research within the project Accurat leading to these results has received funding from the
European Union Seventh Framework Programme (FP7/2007-2013), grant agreement
no 248347.
www.accurat-project.eu