Corpus-based Semantics of Concession

1. Corpus-based Semantics of Concession Livio Robaldo Department of Computer Science, University of Turin robaldo@di.unito.it Eleni Miltsakaki Institute for Research in Cognitive Science, UPenn elenimi@seas.upenn.edu Alessia Bianchini Department of Computer Science, University of Turin alessia.bianchini84@gmail.com

2. The PDTB: Discourse relations • They are conveyed by lexical items connecting two textual spans. Examples: • On the one hand, John loves Barolo. • Sohe went and ordered three cases. • On the other hand, he didn’t have much money. • Sothenhe had to cancel the order.

3. Discourse relations On the one hand – On the other hand John loves Barolo. he went and ordered three cases. So he didn’t have much money. So he had to cancel the order. then

4. PDTB The Penn Discourse Treebank is, to date, the largest annotation effort at the discourse level (more than 40000 annotations). • It encodes discourse relations associated with discourse connectives. • It includes implicit connectives. E.g. • [John broke his arm]arg1. • (implicit=so) [Now, he can’t cycle to work]arg2 • Annotations are made on the Penn Treebank, including approximately 1 million words, taken from the Wall Street Journal.

5. Sense annotation in the PDTB Some discourse connectives can be ambiguous and encompass more than one meaning. E.g. since: Temporal Since [the first fraud was discovered in July 1986 at an office of the People’s Bank of China]arg2, [15 major cases have been found]arg1. Causal [It was a far safer deal for lenders]arg1since [NWA had a healthier cash flow and more collateral on hand]arg2.

6. Aim of the sense annotation The aim of the annotation of senses is to provide sense tags which will flag the intended interpretation of the connectives. Identifying senses has proved to be a challenging task. Fine grained or coarse grained distinctions? Extensive sense annotation studies have been carried out to disambiguate the meaning of verbs (see, for example, Propbank: http://verbs.colorado.edu/~mpalmer/projects/ace.html). Much less for discourse connectives…

7. Semantic CLASSes

8. Comparison CLASS Types

9. Concession • The Type Concession applies when: • Arg2 event/state A implies an event/state C but • Arg1 event/state B states or implies ~C • OR • Arg1 event/state A implies an event/state C but • Arg2 event/state B states or implies ~C • The former is tagged as ‘expectation’, the latter as ‘counter-expectation’.

10. Literature on Concession • A general defeasible rule “Beatiful women usually married ” holds in the context. • This rule creates the expectation that Greta Garbo married. • Argd directly denies this expectation, by asserting exactly the opposite. In the literature [Winter & Rimon, 94], [Lagerwerf, 98], [Korbayova & Webber, 07], twocaseshavebeendistinguished, accordingtohow the expectationisdenied: directly or indirectly. • Direct Contrast: Although [Greta Garbo was considered the yardstick of beauty]Argc, [she never married]Argd.

11. The concessive relation involves an intermediate proposition, called the Tertium Comparationis (TC) [Lagerwerf, 98], defeasibly implied by Argc and whose negation is (non-defeasibly) implied by Argd. • In the example below, the TC is “John is not mobile”: Argc defeasibly implies that John is not mobile, while Argd implies that he is mobile. Literature on Concession In the literature [Winter & Rimon, 94], [Lagerwerf, 98], [Korbayova & Webber, 07], twocaseshavebeendistinguished, accordingtohow the expectationisdenied: directly or indirectly. • Indirect Contrast: Although [John does not have a car]Argc, [he has a bike]Argd.

12. Logical accounts of Concession PreviouslogicalaccountsofConcessionmirror the distinctionbetweenDirect and IndirectContrast. • Direct Contrast: (p ∧ q) ∧ (p →¬q) • Indirect Contrast: (p ∧ q) ∧ ∃r[(p →¬r) ∧ (q → r)]

13. Previous accounts of Concession • PreviousapproachestoConcessionmainly focus on how the expectationisdenied (eitherdirectly or indirectly). • They are almostsilentabouthow the expectationiscreated, i.e. on the relationbetweenArgc and the expectationthatmustbepresupposed. • Some [Lagerwerf, 98], [Sanderset al., 92] generally state itisof a causalnature. • Wethinkthatcharacterizinghow the relation iscreatediscrucialfordefining the semanticof concessive relations. Wetriedto take a first stepstartingfromanempiricalanalysisof PDTB data.

14. Four subcases of Concession Toy examples: • Causality: Although [John studied hard]argc, [he did not pass the exam]argd. • Implication: [Penguins are birds]argc. Nevertheless [they do not fly]argd • Correlation: [John will write the report]argc but [he'll finish it at home]argd • Implicature: Although [John ate a lot of pizza]argc [he did not eat it all]argd.

15. From the PDTB: • Causality:Although [theyrepresentonly 2% of the population]argc, [theycontrolnearlyone-thirdofdiscretionaryincome]argd. • Implication: [The prime minister]argd [whose hair is thinning and gray and whose face has a perpetual pallor]argc nonetheless [continues to display an energy, a precision of thought and a willingness to say publicly what most other Asian leaders dare say only privately]argd. • Correlation: [The Treasurywillraise 10 billion in freshcashbyselling 30 billionofsecurities...]argc. But [ratherthan sell new 30-year bonds, the Treasurywillissue 10 billionof 29-year, nine-monthbonds]argd. • Implicature: Although [it is not the first company to produce the thinner drives]argc, [it is the first with an 80-megabyte drive]argd.

16. Empirical (double) annotation on 1000 PDTB tokens Inter-annotator agreement  k = 0.8 • The analysis provides some evidence that the source of expectation is not always a causal relation.

17. Implication Necessary conditions, rather than causal effects, inherited from some kind of prototype. • Although [workingfor USA intelligence]argc, [Mr. Noriega washardlyhelping the U.S. exclusively]argd. • Although [insider trading has long been criminal]argc, [forexampleithasneverbeenstatutorilydefined]argd. • [You can do all this]argc even if [you’re not a reporter or a researcher or a scholar or a member of Congress]argd.

18. Correlation Divergence from a contextually relevant trend • Although [the notes held at a price of 92 to 93 immediately after the reset]argc, [they started falling soon afterward]argd. • [The LDP won by a landslide in the last election, in July 1986]argc. But [less than two years later, the LDP started to crumble, and dissent rose to unprecedented heights]argd. • [Yet the rowing machine hasn't been touched since]argdeventhough [he has moved it across the country with him twice]argc

19. Correlation Events that “surprisingly” occurtogether • Although [started in 1965]argc [Wedtech didn’t really get rolling until1975]argd. • [The favorite remains Fernando Collor de Mello, a 40-year-old former governor of the state of Alagoas]argc. But […Mr. Collor has slipped to about 30% in the polls from a high of about 43% only a few weeks ago]argd. • [The Journal listed the creation of the money fund as one of the 10 most significant events in the world of finance in the 20th century]argc. But [the Reserve Fund, America’s first money fund, was not named, nor were the creators of the money-fund concept, Harry Brown and myself]argd.

20. Implicature Violationof a GriceanMaxim: Argcisinsufficient or unrelevantwithrespectto the speaker’s intentions. • Although [John ate a lotof pizza]argc [hedidnoteatitall]argd. • [Open the computer case]argcbut [do nottouch the wires]argd. • Although [it is not the first company to produce the thinner drives]argc, [it is the first with an 80-megabyte drive]argd.

21. Thank you!