NLP 1 An Introduction to Pragmatics in NLP. GSLT, Göteborg, March 2006. Barbara Gawronska, Högskolan i Skövde. Reading list:. Jurafsky & Martin, part IV
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Göteborg, March 2006
Barbara Gawronska, Högskolan i Skövde
Semantics investigates meaning ”as part of the language system irrespective of wider context”
This implies that the study object of semantics and pragmatics comprisesinteractions between entities on different levels of the linguistic structure. Pragmatics takes even interactions between the linguistic and the non-linguistic reality into account.
E.g. identification of discourse referents (entities referred to) in spoken language requires an interplay between phonetic/phonological, morphological, syntactic, and semantic factors as well as the use of extralinguistic knowledge.
User and system have different background knowledge:
The system gives an answer that is true, but not relevant:
Discourse processing for
Mary met John. He/She/They decided...
She helped her/herself
I bought a bottle of wine, sat down on a stone, and drankit
in interaction with semantic and grammatical constraints
My friends have a greyhound. They are really huge beasts
They prohibited them from demonstrating because they feared violence
They prohibited them from demonstrating because they advocated violence
Left-to right, breadth-first search, starting with the sentence containing the pronoun
Backward lookning center (CB) - the entity currently in focus
Forward looking centers (CF) - an ordered list of entities:
Subject > Predicative NP > direct object >oblique > PP
”Preferred center” (CP) - the highest ranked forward looking element
A ranked set of transitions:
* For an interesting approach to collocations (collostructional analysis), see Gries, Hampe, & Schönefeld 2005
Success rate: Number of sucessfully resolved anaphors/Number of all anaphors
(Different variants paying atention to trivial and non-trivial anaphors)
The Theory of Mental Spaces (Fauconnier approach (Mitkov 1998)1985, Fauconnier and Sweetser 1996 – focus on beliefs and attitudes)
The Theory of Mental Spaces (2) approach (Mitkov 1998)
(Fauconnier 1985, Sweetser & Fauconnier 1996, Sanders & Redeker 1996)
e.g. result, cause, elaboration, contrast, parallel...
John bought a dog. His wife went furious (result)
John hid Bill’s car keys. Bill had drunk too much (explanation)
John bought a Mercedes. Bill leased a BMW (parallel)
I saw a little dog. Dogs like bones. Bones are white. White is my favourite colour...
TEXT WITH AGGREGATION: approach (Mitkov 1998)IcelandIceland is situated in the north Atlantic.
Iceland has a coastline of 5 000 km and an area of 103 000 sq km. The highest point, Hvannadalshnukur, is 2 119 m. Iceland has a temperate climate with mild, windy winters and cool, damp summers. Iceland has 280 000 inhabitants and the population density is 3 people/sq km. The life expectancy is 79 years and the fertility rate is 2 children.
The official language is Icelandic, a germanic language. Iceland is a constitutional republic. The capital, Reykjavik, has 107 000 inhabitants.The national holiday is June 17.
The outline of the summarization process in Newspeak (Gawronska et al. 2004)
Some principles for selection of claims to be rendered: (Gawronska et al. 2004)
Some principles for selection of claims (Gawronska et al. 2004)
to be rendered:
Some principles for selection of claims (Gawronska et al. 2004)
to be rendered (2):
2) Utterance refusal, negated speech act phrases, hypotheses, commissives, interpretations: The Israeli sources neither denied or confirmed, the minister did not say, if…, the defense secretary declined to say…, the government had no immediate comments…
Utterance refusals or negated speech act phrases related to an explicit claim are omitted
If a source refuses to confirm/deny a claim that has not been explicitly mentioned in the previous part of the text, the whole speech act is rendered, inclusive the type of the speech act
Hypotheses and commissives are rendered together with their sources and marked for unsure epistemic status
Some principles for selection of claims to be rendered (3): (Gawronska et al. 2004)
3) Epistemic spaces: e. g. no one knows if the device was planted deliberately or if it was leftover from New Year’s Eve
If two claims would exclude each other in the same mental space, and if no source in the text takes responsibility for any of these claims, both claims are to be rendered as hypotheses
Some challenges… (Gawronska et al. 2004)
RAMALLAH, West Bank -- Palestinian leader Yasser Arafat said Thursday that elections as part of a reform of the Palestinian Authority will be held this winter, whether or not Israeli forces withdraw from the Palestinian territories.
That represented a change of course from Arafat, who said last week that no elections would be held until the Israelis pulled back. Shortly after Arafat's announcement, a committee he had appointed to set up elections resigned, according to Israel Radio, because Arafat would not agree to a specific date for the elections. Other Palestinian leaders said the resignations were a procedural matter. Arafat also condemned Wednesday's suicide bombing in the Israeli town of Rishon Letzion . Two Israelis were killed and at least 37 others wounded when the bomber detonated explosives in the center of a crowded pedestrian district.
The terror attack marked the second time in two weeks a suicide bombing directed at civilians has rocked Rishon Letzion, a town about 15 miles southeast of Tel Aviv. On May 8, a suicide attack at a pool hall killed 15 people and wounded dozens of others.
"Suddenly there was an explosion," 16-year-old Shmuel Voller told The Associated Press on Wednesday.
The bombing occurred on Rothschild Street in the heart of the town around 9:15 p.m. (2:15 p.m. ET).
An example of non-verbal “summaries”: extracting pathway maps similar to those in Kyoto Encyclopaedia of Genes and Genomes (KEGG) from biomedical literature
- knowledge stored in lexicons, onomasticons, and ontologies
Pragmatics – still a challenge for NLP
Research needed on: