1. Korpuslinguistik mit und für Computerlinguistik
Martin Volk
Universität Zürich
Eurospider Information Technology AG

2. Sources for linguistic information
Introspection (own usage and judgement)
Usage and judgement by others
Questioning (goal-driven)
interview
questionaire
Observation ('involuntary' utterances)
spoken utterances ( corpora)
written utterances ( corpora)
observation: first-language acquisition (cursory observation)
experimental observation: e.g. eye movement tests
Martin Volk
28 November 2018

3. What is a corpus? a text collection a representative text collection
a representative and structured text collection
a representative, structured and annotated text collection
...
Martin Volk
28 November 2018

4. Example Is 'ob' used as a preposition in German? Introspection
Rothenburg ob der Tauber
Dictionary (Wahrig. Deutsches Wörterbuch. 1996): Präp. mit Dativ; veraltet; ob dem Wasserfall
Web: Google 'ob dem'
Sage: Der Wilde Jäger ob dem Neuenburgersee
Corpus
Check 'ob' in IdS-Corpus!!
Program for CZ corpus:
perl ../find_special_sent.perl cz94*snv
Martin Volk
28 November 2018

5. Corpus Examples
CZ94: ... fiel schier vom Stuhl ob der Äusserung eines Ozeanologen ...
CZ94: Bei manchem Ölgiganten kam ob der Ergebnisse gar Euphorie auf.
CZ94: ... rieben sich vergnügt die Hände ob des zu erwartenden Schlagabtauschs.
ob is a preposition with genitive!!
in CZ corpus: 'ob' is tagged as preposition 21 times (obviously some incorrect)
Martin Volk
28 November 2018

6. History of Corpus Linguistics
collections of text were widely used in the 19th century and in the first half of the 20th century
language acquisition
orthography (letter frequency)
field linguistics
 American Structuralism (influential until 1960)
Martin Volk
28 November 2018

7. History of Corpus Linguistics
Chomsky's criticism: Speakers produce and understand infinitely many new sentences/words.
therefore the new research goal is: to describe the underlying language faculty of a speaker (= universal grammar), competence rather than performance
Martin Volk
28 November 2018

8. History of Corpus Linguistics
Chomsky's criticism: every collection of texts is a collection of performance data and so many factors contribute to it that it cannot be used to model competence.
A corpus is necessarily skewed. Some sentences won't occur because they are obvious, false or impolite.
Martin Volk
28 November 2018

9. History of Corpus Linguistics
theoretical linguistics
competence (what is grammatical?)
introspection
indefinitely many types, productivity
grammatical vs. ungrammatical
corpus linguistics
performance (what is attested?)
instances
finite number of types
degrees of grammaticality
Martin Volk
28 November 2018

10. Corpus research in Linguistics
Lexicography (Dictionaries)
Grammaticography (Reference grammars)
Learner corpora: Language acquisition
Parallel corpora: Translation
Martin Volk
28 November 2018

11. Construction of Corpora
Written text is easier to obtain than spoken text. Some examples:
Newspapers
Fiction (e.g. fairy tales)
Technical Literature (e.g. manuals, medicine)
Personal letters:
Advertising (incl. political propaganda)
Belief and Thought (e.g. bible)
Martin Volk
28 November 2018

12. Corpora of spoken language
Spontaneous spoken language
recording of dialogues (e.g. telephone conversation)
Prepared spoken language
Public speeches (e.g. in parliament)
Radio or TV news
Spoken utterances must be transcribed for linguistic research.
Martin Volk
28 November 2018

13. Size of corpora Brown Corpus for English (1964, 1 Mio. words)
LIMAS-Corpus for German (1970, 1 Mio. words)
British National Corpus (1995, 100 Mio. words)
Cosmas corpus (2002, > 100 Mio. words)
Martin Volk
28 November 2018

14. Brown Corpus (1964) 500 texts out of 15 different text types
with 2000 words each
Martin Volk
28 November 2018

15. British National Corpus
90% written English, 10% spoken English
3209 texts
out of 10 different text types written and
6 text types spoken
with < 40'000 words each
 multi-purpose corpus
Martin Volk
28 November 2018

16. Other considerations Time frame of the corpus
Native and non-native speakers
Sociolinguistic variables
Gender
Age
Education
Dialect
Social context and relationships
Martin Volk
28 November 2018

17. Types of corpora Raw texts Automatically annotated corpora
Texts with Part-of-Speech tags
Partially parsed texts
Manually annotated corpora
Treebank
FrameNet
Martin Volk
28 November 2018

18. Types of Corpora Balanced Corpora vs. special corpora
Spoken vs. written language
Monolingual vs. Multilingual Corpora
Parallel vs. comparable corpora
Martin Volk
28 November 2018

19. Corpora in Computational Linguistics
annotation
Linguistic Facts: 'Peter Smith'  'Smith' is a last name
Linguistic Rules/Heuristics: if a word can be determiner or pronoun and the following word is a noun, then it must be a determinier.
Linguistic Preferences: if an English prepositional phrase starts with 'of', then it must be attached to the preceding noun with 90% probability.
Facts
Rules
Preferences
learning
Martin Volk
28 November 2018

20. My Motivation for Corpus Linguistics
Attempt to build a parser for German
But: problems with ambiguities!!
Therefore: Learn attachment preferences from a corpus!
Martin Volk
28 November 2018

21. Corpora vs. Test suites A test suite
is a collection of manually constructed and selected sentences.
is used for testing computational grammars and parsers.
reduces the amount of testing.
leads to specific problems of the NLP system.
Martin Volk
28 November 2018

22. Basic problems in CL Knowledge is missing (too little information)
e.g. unknown words
Ambiguities (too much information)
e.g. in syntax: attachment preferences
Martin Volk
28 November 2018

23. Corpora in Computational Linguistics
Widespread use of (manually) annotated material for measuring progress!
Some examples from COLING 2002:
Treebanks to train and test probabilistic grammars
Enriching treebanks with dependency information
Automatic error detection in PoS-Tagged Corpora
SENSEVAL data to train and test word sense disambiguation programs
Martin Volk
28 November 2018

24. Possible Student Tasks
Which German prepositions take a noun without a determiner? (e.g. pro, via)
When is mit used as an adverb? (e.g. )
What is the distribution of separable verb prefixes in German?
How often are relative clauses introduced with welche(r) ?
How often are present participle forms used in German?
What kind of foreign language material is in the corpus?
Martin Volk
28 November 2018

25. Possible Student Tasks
Create a small parallel corpus (e.g. with various versions of 'Alice in Wonderland' or National Geographic)
Create a small corpus of spoken language (e.g. by transcription of one issue of 'Big Brother').
Create a small treebank with the ANNOTATE tool.
Martin Volk
28 November 2018

26. What corpora do we have for German?
Raw text
ComputerZeitung (about 1.3 million words per year)
ComputerZeitung iX
Tages-Anzeiger 2000
Martin Volk
28 November 2018

27. Information in TagesAnzeiger
Date
Category (Sport, Politics, Culture, Economics etc.)
Author
Title vs. Text
Martin Volk
28 November 2018

28. What corpora do we have for German?
Syntactically Annotated Text (Treebanks)
NEGRA treebank (20'000 sentences)
ComputerZeitung treebank (3'000 sentences)
Text with manually corrected PoS tags
50'000 sentences from University speeches
others
Martin Volk
28 November 2018

29. If you can talk, you can sing. If you can parse, you can understand.
The goal
If you can walk, you can dance.
If you can talk, you can sing.
If you can parse, you can understand.
(Hans Uszkoreit, COLING 2002)
Martin Volk
28 November 2018

30. Acknowledgement
Some slides were highly influenced by or even copied from Anke Lüdeling's course "Introduction to Corpus Linguistics" at
Martin Volk
28 November 2018