Corpus-driven genitive disambiguation

Nadine Aldinger - Corpus Linguistics 2005, Birmingham, 07/17

1 Nominalizations and genitive attributes (1)

1 Nominalizations and genitive attributes (2)

Context parameters usable for corpus-based disambiguation

1. morphosyntactic form of the NP headed by the nominal:
   i.e. number and definiteness, maybe case
   Messungen (a) vs. die Messung (b)
   
   
2. syntactic structure of the local context:
   inner structure of the nominal's NP, but also embedding in PPs/VPs
   PP-laut (a)
   
   
3. properties of the nominal's base verb:
   e.g. telicity, syntactic subcategorization
   measure (subj, s-comp(C_dass))
   
   
4. lexical material in the local context:
   e.g. selectional restrictions on the governing verb
   dienen "to serve" (b)
   
   

2 Finding and evaluating context parameters for genitive disambiguation

1. Collect linguistic context parameters that might be relevant for genitive interpretation from literature and from (qualitative) corpus observations.
   
   
2. Collect corpus sentences containing representative nominalizations plus genitive attributes in a database and annotate their parameter values automatically.
   
   
3. Annotate genitive interpretation manually for each sentence.
   
   
4. Analyze frequency distributions to find the parameters and parameter combinations that are most useful to predict genitive interpretation.
   
   
5. Implement tests based on these combinations.
   
   
6. Re-run the tests on new corpus sentences and evaluate the quality of their predictions for genitive interpretation; if necessary and possible, improve the tests and look for more diagnostic parameters (bootstrapping).
   
   

3.1 Corpus architecture

German newspaper corpus (Frankfurter Rundschau 1992-93), ~40 million words;
pre-processed:

• tokenized
• part-of-speech tagged (TreeTagger, STTS tagset)
• lemmatized (TreeTagger)
• morphosyntactically annotated (DMOR)
• chunked / partially parsed (YAC)

Tools:

• IMS Corpus Workbench (CWB)
• powerful regular-expression query language (CQP)
• Perl scripting interface
• MySQL database
• PHP/HTML-based database interface

3.2 Database layout (1): Tables

• all nominals in the corpus with frequency values and compound information
  
  
• all base verbs of the nominals with complete subcategorization information
  
  
• corpus matches of nominal + genitive attribute (in sentence) annotated with context parameters (automatically) and genitive interpretation (manually)

3.2 Database layout (2): Examples

3.2 Database layout (3): Nominals

3.4 Database layout (4): Base verbs

3.2 Database layout (5): matches and annotated features (a)

3.2 Database layout (6): matches and annotated features (b)

* planned

3.3 Extraction procedure

3.4 Classification of genitives

• subject genitive
  die Befürchtung der Gewerkschaft "the fear of the trade union"
  
  
• object genitive
  die Befürchtung einer Finanzkrise "the fear of a financial crisis"
  
  
• subject genitive with non-transitive base verb
  intransitive: eine Erkrankung des Herzens "a disease of the heart", base verb erkranken "to fall sick";
  inherently (or very preferably) reflexive: die Annäherung des Autos "the approach of the car", base verb sich annähern "to approach"
  
  
• other thematic genitives (from indirect, genitive, or prepositional objects)
  in Ermangelung guter Alternativen "for lack of good alternatives", base verb ermangeln (dummy subject, genitive object or an-PP) "to lack"
  
  
• non-thematic genitives (temporal, modal, with superlative, quantitative)
  
  
• genitive modifying the non-head of a compound nominal
  die Altersverteilung der Studenten "the age distribution of the students"
  
  

4 First results (1)

Candidate parameters determining subject-to-object genitive ratio

• number of the nominal
  Verfolgung "pursuing, persecution" (3 subject genitives : 178 object genitives) vs. Verfolgungen "pursuings, persecutions" (2 : 1)
  
  
• availability of Object reading (i.e. whether the nominal can refer to a physical or abstract object)
  Herstellung "production" (0 : 369) vs. Veranstaltung "event, function" (357 : 14)
  
  
• subcategorization properties of the nominal's base verb: most notably for content/informational Objects, i.e. "Object" instances of nominals from proposition-embedding verbs
  Äußerung "utterance" (343 : 10)
  
  

4 First results (2): Singular vs. plural nominals (a)

4 First results (3): Singular vs. plural nominals (b)

• some plural nominals have a high rate of subject genitives compared to their singular form
• some (most?) nominals which occur exclusively with object genitives in singular form have no plural at all
• predominance of Object readings with plural nominals - no "real" subject genitives there

5 Summary

• task: disambiguation of genitive attributes of nominalizations
  
  
• approach: derive useful context parameters from large amounts of corpus data
  
  
• proof of concept: plural

6 Next steps

enlarge example database

• more examples
  
  
• more parameters:
  
  
  • sortal reading of the nominal
    at least distinguish Process/Event from Result State/Object
    
    
  • clausal context, esp. main verb
    requires full or partial parsing or manual annotation/checking
    
    
  • thematic proto-roles of base verbs
    requires manual annotation
    
    
  • ontological information
    for genitive attributes, e.g. strong preference for animate subject genitives
    for embedding verbs and prepositions, e.g. spatial verb -> Object reading