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The DAD corpora and their uses

The DAD corpora and their uses. Costanza Navarretta costanza@hum.ku.dk Funded by Danish Research Councils – Sussi Olsen, CST. The DAD corpora.

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The DAD corpora and their uses

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  1. Centre for Language Technology The DAD corpora and their uses Costanza Navarretta costanza@hum.ku.dk Funded by Danish Research Councils – Sussi Olsen, CST

  2. Centre for Language Technology The DAD corpora • Parallel or comparable texts and dialogues in Danish and Italian annotated with information on third-person singular neuter personal pronouns and singular demonstrative pronouns (3sn). • Focus on abstract anaphoric uses (abstract pronouns AA), i.e. antecedent is a copula predicate, a verbal phrase, a clause, a discourse segment.

  3. Centre for Language Technology Abstract Anaphora in English • it, this, that • Strong preference for use of demonstrative pronouns to refer to entities introduced in discourse by clauses - 83.7% of occurrences in written corpus (Webber 1991). • Similar figures in English written and spoken data (i.a. Byron & Allen 1998, Gundel et al. 2003, 2005).

  4. Centre for Language Technology Abstract Anaphora in Danish • written Danish: • det (it/this/that) • dette (this) • spoken Danish: • unstresseddet (it) • d'et (this/that), • d'et h'er(this) • d'et d'er(that) • dette (this) – very seldom

  5. Centre for Language Technology Abstract Anaphora in Italian • zero anaphora (subject pro-drop language); • clitics –lo, -ne, -ci; (it) • personal pronouns lo, ne,ci; • demonstrative pronouns: ciò(this/that), questo (this), quello (that)

  6. Centre for Language Technology The Annotations • Texts: structural information, PoS and lemma (various tagsets) • Spoken data: PoS, (lemma), stress, (prosody, phrases), speakers, interaction segments, utterances, timestamps • All data (Navarretta & Olsen LREC-2008): • 3sn: pronominal function (9), syntactic function • anaphoric occurrences: referential links and their type, antecedents, syntactic type of antecedents, anaphoric distance • when AA also semantic type of reference

  7. Centre for Language Technology Spoken Corpora (da 100000, it 70000) • dialogues from AVIP, Italian map-task corpus, Pisa, Napoli, Bari (ftp://ftp.cirass.unina.it/cirass/avip); • dialogues and monologues from Danish map-task corpus DanPASS (Grønnum, 2006); • 3. multiparty spontaneous dialogues from the Danish LANCHART corpus (Gregersen, 2007); • 4. transcriptions of TV-interviews;

  8. Centre for Language Technology Written corpora (da 60000, it 50000) • Pirandello’s (1922) stories and Danish translations; • parallel Danish and Italian EU texts; • articles from Italian financial newspaper, Il Sole 24 Ore; • Danish juridical texts; • extracts from the Danish general language PAROLE corpus (Keson and Norling-Christensen, 1998); • .

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  12. Centre for Language Technology Discussion • Many factors influence the use of pronouns, see i.a. Hajičová et al. (1990), Borthen et al. (1997), Kaiser (2000), Kaiser and Trueswell (2004), Gundel et al. (2003), Navarretta (2002, 2005). • Navarretta (WARII-2008): the differences in the use of AA pronouns in Danish and Italian with respect to English are systematic. • Language specific characteristics can partly explain these differences.

  13. Centre for Language Technology Pronominal Systems • Pronouns for inanimate entities • English: 1 gender • Danish and Italian:2 inanimate genders • Danish: common and neuter – only latter can be abstract anaphor • Italian: feminine and masculine – only latter can be abstract anaphor • In English more necessary to restrict interpretation: via distinction personal-demonstrative pronoun

  14. Centre for Language Technology Syntax • constructions as clefts and left dislocations are much more frequent in Danish than in English and Italian, thus in Danish the clause is often the entity which is in "focus" (Gundel et al. 1993) – this partly explains the frequent use of personal pronouns (det and unstressed det) with clausal antecedents; • word order is relatively free in Italian opposed to Danish and English: • the use of abstract substantives in Italian restricts the antecedent search space;

  15. Centre for Language Technology Machine Learning Experiments on Danish data (Navarretta – DAARC 2009) • Classifying the function of 3sn-pronouns using the pronominal context (n-grams of various size) and the annotated function (only in training), see i.a. (Evans 2000, Müller 2007, Hoste et al. 2007) • More classifiers run on data as proposed by Daeleman et al. (2005), but more types of data and more fine-grained classification. • Weka (Witten and Frank, 2005): results evaluated using 10-fold cross-validation; • Baseline: results by ZeroR which proposes most frequent nominal category.

  16. Centre for Language Technology Results (F-score) • texts: 62.4%, monologues: 64.7%, map-task dialogues: 55.4%, multiparty dialogues: 32.9% (improvement: 36.4%, 30.7%,33.7% and 19.1% with respect to the baseline respectively); • results on texts and map task data in line with results obtained on more restricted tasks, e.g. recognition of het by Hoste et al. (2007); • recognition of non-referential pronouns slightly lower than in i.a. Boyd et al. (2005); • adding pos and lemma information to data improves classification, but not significantly, same result as in Hoste et al. (2007);

  17. Centre for Language Technology Classification experiments on Italian

  18. Centre for Language Technology Results on Italian data • Improvement of classification with respect to the baseline is 55.1% for texts, 35.9% for dialogues. • There are more types of pronouns in Italian than in Danish, thus the use of each type of pronoun is much more restricted in the former language than in the latter. • Adding PoS and lemma information decreases performance of classifier, but not significantly.

  19. Centre for Language Technology Conclusion and future work • annotations in DAD corpora: characteristics of use of 3sn in Danish and Italian; • differences in use of AA in Danish, English and Italian can be explained in terms of languages' pronominal system and syntax; • annotations useful to automatically distinguish function of 3sn; • to do: look at relation between pronouns, clausal types of antecedents and anaphoric distance –look at parallel data, investigate resolution, investigate use of lexical resources...

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