1. Experiments with Annotating Discourse Relations in the Hindi Discourse Relation Bank (HDRB) Umangi Oza†, Rashmi Prasad‡ Sudheer Kolachina†, Suman Meena§ Dipti Misra Sharma†, Aravind Joshi‡ † Language Technologies Research Center International Institute of Information Technology, Hyderabad, India § Center for Language, Literature and Cultural studies Jawaharlal Nehru University, NewDelhi, India ‡ Institute for Research in Cognitive Science/ Computer and Information Science University of Pennsylvania, Philadelphia, PA, USA

2. December 2009, ICONHDRB, Umangi et al.2 Introduction: Why Discourse? For many NLP applications, such as Question-Answering, Text Summarization, and Language Generation, sentence- level analysis derived from an annotated corpus is insufficient, e.g., – Penn Treebank (PTB) (Marcus et al., 1993) – Propbank (Palmer et al., 2005) Need for discourse-level information – Penn Discourse Treebank (Prasad et al.,2008) – Annotation over the same WSJ raw corpus as PTB and Propbank has resulted in an enriched annotated resource – The browser allows the viewing of both annotations

3. December 2009, ICONHDRB, Umangi et al.3 Penn Discourse TreeBank (PDTB) (Prasad et al., 2008): Large-scale corpus of lexically-grounded annotations of discourse relations between abstract objects (AOs) Discourse Relations: cause, contrast, elaboration, etc. Abstract Objects: eventualities and propositions (Asher, 1993) Discourse relation triggers: – Explicit connectives “closed-class” expressions from well-defined grammatical classes – Alternative Lexicalizations (AltLex) Expressions not definable as explicit connectives – Implicit connectives: “inferred” relations for which connectives are “inserted”

4. December 2009, ICONHDRB, Umangi et al.4 PDTB When no discourse relation can be inferred: – EntRel (an entity-based coherence relation) – NoRel (no discourse relation) Abstract object arguments of a discourse relation: – called Arg1 and Arg2 – Arg2 goes with the clause/AO in which the connective occurs Minimality Principle: – Select only as much as the argument text span as is minimally necessary to interpret the relation Sense Annotation: – Each relation assigned a sense label based on a hierarchical sense classification scheme

5. December 2009, ICONHDRB, Umangi et al.5 PDTB examples Convention: Arg1 [] and Arg2 {} Explicit Connective: – [By most measures, the nation’s industrial sector is now growing very slowly]. Factory payrolls fell in September. So did the Federal Reserve Board’s industrial production index. Yet, {many economists aren’t predicting that the economy is about to slip into recession.} (sense: Concession) AltLex: – [Under a post-1987 crash reform, the Chicago Mercantile Exchange wouldn’t permit the December S&P futures to fall further than 12 points for an hour.] {That caused a brief period of panic selling of stocks on the Big Board.} (sense: Result) Implicit Conective: – [The voters, as well as numerous Latin American and East European countries that hope to adopt the Spanish model, are supporting the direction Spain is taking.] IMPLICIT=SO {It would be sad for Mr. Gonzalez to abandon them to appease his foes.} (sense: Result)

6. December 2009, ICONHDRB, Umangi et al.6 Hindi Discourse Relation Bank (HDRB) HDRB aims at creating a large-scale annotated corpus of discourse relations in Hindi texts, following the PDTB approach. Corpus: – 200 K size corpus drawn from 400 K on which Hindi syntactic dependency annotation being conducted independently (Begum et al., 2008) – Multi-domain newspaper corpus Other cross-linguistic discourse annotation projects: – Chinese (Xue, 2005) – Czech (Mladova et al., 2008) – Turkish (Zeyrek and Webber, 2008)

7. December 2009, ICONHDRB, Umangi et al.7 Syntactic Classes of Explicit Connectives Explicit Connectives are “closed-class” expressions drawn from a set of well-defined grammatical classes. Subordinating conjunctions Coordinating conjunctions Adverbials Pied-piped sentential relativizers Subordinators Particles

8. December 2009, ICONHDRB, Umangi et al.8 Subordinating Conjunctions Lexical items conjoining finite adverbial clauses to their matrix clause Typically occur clause-initially Both single (e.g., क्योंकि (because)) and paired forms (e.g., अगर... तो (if..then))  [ आज दीया जलाया गया है ] क्योंकि { आज मेरी वर्षगाँठ है.} (Cause) ‘[Today the lamp has been lit] because {it is my birthday}.’  अगर [ कोई आपसे कहे की नमक छोड़ दो ] तो { आप भी नहीं छोड़ेंगे } (Conditional) ‘If [one were to ask you to quit taking salt] then {even you would not quit}.’

9. December 2009, ICONHDRB, Umangi et al.9 Coordinating Conjunctions Lexical items conjoining clauses or phrases of the same syntactic status Occur clause-initially, e.g., और (and), लेकिन (but) Single as well as paired forms e.g., न केवल … बल्कि (not only...but also)  [ संघ के संगठन अनेक हैं ] किन्तु { विचारधारा एक ही है. } (Concession) ‘[There are many groups in the Sangh] but {there is just one ideology.}’

10. December 2009, ICONHDRB, Umangi et al.10 Adverbials Adverbial and prepositional phrases claimed to function as anaphoric discourse (Webber et al., 2003) Some examples of these are सो (so), फ़िर (then), नहीं तो (otherwise), वास्तव में (in fact), तभी (just then), इसके अलावा (in addition to this) etc.  [ दानवी लहरों के कारण अंडमान के पश्चिमी तट पर तटीय वनस्पति पूरी तरह बर्बाद हो गयी.] इसके अलावा { मूंगे के चट्टानों को भी नुक्सान हुआ है.} (Expansion) ‘[The coastal vegetation on the west coast of the Andaman has been completely destroyed due to wild waves]. In addition, {the coral reefs have also been damaged}.’

11. December 2009, ICONHDRB, Umangi et al.11 Pied-piped Sentential Relativizers Pied-piped relative phrases that conjoin a relative clause with the predication of its matrix clause (rather than some NP) Examples are जिससे (so that), जिसके कारण (because of which)  [ सारा काम छोड़कर वह उस चिड़िया को उठाकर दवाघर की ओर भागा ] जिससे { उसका सही इलाज किया जा सके.} (Cause) ‘[Dropping all his work, he picked up the bird and ran towards the dispensary] so that {it could be given proper treatment}’ The relative pronoun जिससे modifies the event expressed in the matrix clause

12. December 2009, ICONHDRB, Umangi et al.12 Subordinators Post-positions, verbal participles, and suffixes that introduce non-finite clauses  { बा के जाने } के बाद [ उन्होंने उस लडके को अपने पास बुलाया.] (Succession) ‘After {Baa left} [he called the boy to him].’ ... { खेलते } हुए [ यह भूल जाता है की यदि उसका मित्र भी उसे अपने खिलौने को हाथ लगाने नहीं देता तो उसको कितना बुरा लगता.] (Synchronous) ‘...while [playing] {he forgets that if his friend too didn’t let him touch his toy, then he would feel very bad too].’

13. December 2009, ICONHDRB, Umangi et al.13 Particles Particles such as भी, ही can function as discourse connectives in Hindi  [ लोग इसे दोनों देशों के बीच बड़ते रिश्ते के परिणाम के रूप में देख रहे हैं.] { कश्मीरी लोग इससे एक राजनीतिक सबक } भी { ले रहे हैं.} (Conjunction) ‘[People see this as a consequence of the improving relation between the two countries]. {The Kashmiris are} also {learning a political lesson from this}.’ Instances only where they indicate the inclusion of verbs taken as discourse connectives  उसने कुछ भी नहीं खाया. ‘He didn’t eat anything.’

14. Arguments of Discourse Relations In PDTB, Arg2 is the argument “syntactically” associated with the connective, and Arg1 is the “other” argument. In HDRB, argument naming is based on the sense of the relation. Each relation definition specifies its own convention for argument naming. E.g., In the “cause” relation, one argument is the cause and the other is the effect. HDRB convention: Arg1=effect; Arg2=cause Advantages of semantic naming scheme: More meaningful, and simplifies the sense classification hierarchy. December 2009, ICONHDRB, Umangi et al.14

15. Arguments of Discourse Relations Cause after effect. Hence, Arg1-Arg2  प्रतियोगिता के बाद सोनल ने बताया कि [ विजेता के रूप में जब उसका नाम पुकारा गया तो उसे कुछ देर तक खुद पर विश्वास ही नहीं हुआ ] क्योंकि { वह मान कर चल रही थी कि यह प्रतियोगिता फ़िक्स है.} (Cause) ‘After the competition, Sonal said that [when her name was announced as the winner, she could not believe herself for some time], because {she was thinking that the competition was fixed}.’ Cause before effect (Arg2-Arg1)  फैशन डिजाईनरों का कहना है कि सबसे ज्यादा नक़ल या चोरी मोनोपोली डिजाईन की होती है. { डिजाईनर इन बातों को बखूबी जानते हैं } इसलिए [ कई बार ध्यान नहीं देते हैं.] (Cause) ‘Fashion designers say that the most prevalent thefts or copies are of monopoly designs. {Designers know this fact very well} so [it does not matter to them many times].’ December 2009, ICONHDRB, Umangi et al.15

16. December 2009, ICONHDRB, Umangi et al.16 Implicit Discourse Relations For adjacent sentences not related by an explicit connective, four possibilities are considered in order: (1)Infer a discourse relation and insert an “implicit” connective between them  { इस गेम के सारे खिलाड़ी सचिन तेंदुलकर से भी महान हैं.} IMPLICIT = इसलिए [ इनको क्लीन बोल्ड करना किसी के बस की बात नहीं.] (Causal) ‘{All the players in this game are greater than even Sachin Tendulkar} so [it is not possible for anyone to get them clean bowled.]’ (2) If relation is inferred but insertion of connective leads to redundancy, find and annotate an “alternate Lexicalization” (AltLex) of the relation  { बंगलादेश की कानून व्यवस्था की हालत में सुधार हुआ है } AltLex [ इसी वजह से भारत ने सम्मलेन में शामिल होना का फ़ैसला लिया है ] ‘{Bangladesh’s judiciary has seen an improvement}. That is why [India has decided to participate in the conference.]’

17. Other Relations (3)If no discourse relation is inferred but coherence results from an entity-based relation, annotate relation as “EntRel”.  [ फ़िल्म महोत्सव में प्रकाश झा की नयी फ़िल्म अपहरण का भी प्रीमियर होना है ] EntRel { गंगाजल के बाद झा की यह किसी अलग विषय पर बनी दूसरी फ़िल्म है.} ‘[Prakash Jha’s latest film Apaharan will be premiered at the film festival.] {This is Jha’s second film on a different subject after Gangajal.}’ (4) If no discourse relation or EntRel is perceived, annotate relation as “NoRel” December 2009, ICONHDRB, Umangi et al.17

18. December 2009, ICONHDRB, Umangi et al.18 HDRB Sense Classification Adapted from PDTB

19. December 2009, ICONHDRB, Umangi et al.19 Results Annotated 35 texts from the HDRB corpus Total of 602 relations annotated (both explicit and implicit) Overall distribution of relation types Comparison with PDTB distributions (Prasad et al., 2008)

20. December 2009, ICONHDRB, Umangi et al.20 Types and Tokens of Discourse Relations Lexical strategies employed equally often as morphological marking Design difference between the two projects (implicit relations annotated between ‘all’ adjacent sentences in HDRB unlike PDTB) probably the reason for the different relative proportions of explicit and implicit relations across the two corpora The higher proportion of AltLex compared to PDTB suggests that Hindi makes greater use of cohesive strategies to link with the prior discourse

21. December 2009, ICONHDRB, Umangi et al.21 Senses of Discourse Relations Sense distributions are similar cross-linguistically Chances of “Expansion” and “Contingency” relations being explicit lower compared to “Comparison” and “Temporal” relations

22. December 2009, ICONHDRB, Umangi et al.22 Additional Exploration of Discourse Adverbials Discourse adverbials are argued to be anaphoric (Webber et al., 2003) so that their arguments may be harder to identify than other types of connectives Investigated the disributions of two discourse adverbials to explore the extent of difficulty in resolving their arguments – Contrastive adverbial, इसके बावजूद (nevertheless) – Conjunctive adverbial, इसके अलावा (in addition) Observations – इसके अलावा had non-adjacent LHArgs in 16% of cases – इसके बावजूद always took adjacent arguments Thus, despite their anaphoric properties, some discourse adverbials seem to be more constrained than others, and therefore easier to resolve

23. December 2009, ICONHDRB, Umangi et al.23 Summary Adapting the PDTB scheme to Hindi discourse annotation led to – Identification of syntactic categories for explicit connectives that appear to be more frequent than English (Particles, Sentential Relatives) – More meaningful and simplified sense classification hierarchy Some of our observations from the initial annotations – The correlation between the use of cohesive strategies and morphological richness of a language is not completely settled by our annotations so far. Perhaps, study of languages with morphology richer than Hindi may shed further light on this issue – Sense distributions in both PDTB and HDRB were similar and confirm the lack of expectation of cross-linguistic “semantic” differences – Annotation of discourse adverbials show further evidence of the locality of arguments which can significantly benefit anaphora resolution for connectives

24. December 2009, ICONHDRB, Umangi et al.24 Thank you

25. Questions? December 2009, ICONHDRB, Umangi et al.25

26. December 2009, ICONHDRB, Umangi et al.26 Back-up slides

27. December 2009, ICONHDRB, Umangi et al.27 Subordinators (11) { बा की बातें सुन } कर [ मन ही मन बहुत लज्जित हुए.] ‘Upon {hearing Baa’s words}, [Gandhiji felt very ashamed].’ Some instances of subordinators are not discourse connectives, such as when they denote the manner of an action (Ex.12) (12) उन्होंने बा का हाथ पकड़ा और दरवाज़े तक खींच कर ले जाये. ‘[Lit.] He caught Baa’s hand and took her to the door by dragging her.’ Preliminary annotation experiments suggest that distinguishing the discourse and non-discourse usage of subordinators is a difficult task Annotate them in a later phase of the project

28. December 2009, ICONHDRB, Umangi et al.28 Arguments of Discourse Relations In PDTB, assignment of Arg1/Arg2 labels syntactically driven In HDRB, it is semantically driven i.e, based on the sense of the relation to which the argument belong In examples 15 and 16, both relations have the sense ‘cause’. ‘Cause’ sense definition: one cause and one effect In 15, cause after effect. Hence, Arg1-Arg2 (15) प्रतियोगिता के बाद सोनल ने बताया कि [ विजेता के रूप में जब उसका नाम पुकारा गया तो उसे कुछ देर तक खुद पर विश्वास ही नहीं हुआ ] क्योंकि { वह मान कर चल रही थी कि यह प्रत्योगिता फ़िक्स है.} ‘After the competition, Sonal said that [when her name was announced as the winner, she could not believe herself for some time], because {she was thinking that the competition was fixed}.’

29. December 2009, ICONHDRB, Umangi et al.29 Arguments of discourse relations In 16, cause before effect (Arg2-Arg1) (16) फैशन डिजाईनरों का कहना है कि सबसे ज्यादा नक़ल या चोरी मोनोपोली डिजाईन की होती है. { डिजाईनर इन बातों को बखूबी जानते हैं } इसलिए [ कई बार ध्यान नहीं देते हैं.] ‘Fashion designers say that the most prevalent thefts or copies are of monopoly designs. {Designers know this fact very well} so [it does not matter to them many times].’ According to the PDTB convention, both would have been Arg1- Arg2 (syntactic argument order) Semantics-based convention has the added advantage of simplifying the Sense classification scheme

30. December 2009, ICONHDRB, Umangi et al.30 Implicit Discourse Relations If a relation can be inferred between sentences, an implicit connective is inserted Insertable connectives drawn primarily from the list of explicit connectives, but can include others too (17) { इस गेम के सारे खिलाड़ी सचिन तेंदुलकर से भी महान हैं.} IMPLICIT = इसलिए [ इनको क्लीन बोल्ड करना किसी के बस की बात नहीं.] ‘{All the players in this game are greater than even Sachin Tendulkar} so [it is not possible for anyone to get them clean bowled.]’ In this example, an implicit connective expressing a causal relation is inserted

31. December 2009, ICONHDRB, Umangi et al.31 Implicit Discourse Relations If a discourse relation can be inferred but insertion of a connective leads to ‘redundancy’ in the expression of the relation, it suggests that the second sentence of the pair contains an alternatively lexicalized non-connective expression: AltLex AltLex not a closed class element (18) { बंगलादेश की कानून व्यवस्था की हालत में सुधार हुआ है } AltLex [ इसी वजह से भारत ने सम्मलेन में शामिल होना का फ़ैसला लिया है ] ‘{Bangladesh’s judiciary has seen an improvement}. That is why [India has decided to participate in the conference.]’

32. December 2009, ICONHDRB, Umangi et al.32 Implicit Discourse Relations If no discourse relation can be inferred, Identify an entity-based relation (EntRel) across the two sentences The second sentence provides further description about an entity (or entities) from the previous sentence (19) [ फ़िल्म महोत्सव में प्रकाश झा की नयी फ़िल्म अपहरण का भी प्रीमियर होना है ] EntRel { गंगाजल के बाद झा की यह किसी अलग विषय पर बनी दूसरी फ़िल्म है.} ‘[Prakash Jha’s latest film Apaharan will be premiered at the film festival.] {This is Jha’s second film on a different subject after Gangajal.}’ Only purpose of the second sentence to provide additional information about ‘Jha’s second film’ If neither a discourse relation nor an EntRel, then NoRel (no relation)

33. December 2009, ICONHDRB, Umangi et al.33 Points of Departure from PDTB Sense Scheme Elimination of senses due to syntactic argument-naming conventions (as per HDRB semantic naming convention for arguments) Restricted back-offs in the sense hierarchy (PDTB allowed back-offs upto the top level. But HDRB belief is that top level senses are too coarse-grained to be useful. Thus, back-offs allowed only to the second level) Uniform treatment of pragmatic relations into more refined senses (Epistemic, speech-act, propositional (Sweetser, 1990)) Addition of the “Goal” sense (Was included as a causal relation in PDTB)

34. December 2009, ICONHDRB, Umangi et al.34 Elimination of argument-specific labels While some of the subtype distinctions do represent the arguments’ relative semantic roles; others continue to be refinements of the relations’ semantics Furthermore, it was observed that the distinctions expressed by the subtype labels were related to the variation in the “linear order” of the arguments e.g., ‘reason’ and ‘result’ subtypes under “Contingency.cause”, ‘reason’ (cause after effect) and ‘result’ (cause before effect) In HDRB, the assignment of argument labels is semantically driven and therefore, these subtype labels are eliminated to avoid inconsistencies

35. December 2009, ICONHDRB, Umangi et al.35 Restricted back-offs In PDTB, annotators were allowed to backoff to higher levels in the hierarchy when they found it difficult to identify the more refined senses at the lower levels For example, “Comparison” at the class level instead of “Comparison.Contrast” or “Comparison.Concession” in case of ambiguity between “Contrast” and ”Concession” In HDRB, such backoffs restricted only upto the type level Senses are too coarse-grained to be useful Guideline consistent with the fact that argument ordering specifications are provided at the type level

36. December 2009, ICONHDRB, Umangi et al.36 Uniform treatment of pragmatic relations Pragmatic relations in HDRB based broadly on the distinction made in PDTB between semantic and pragmatic relations (Sanders et al., 1992) Discourse relations are viewed as Semantic when they relate the propositional content of the arguments Pragmatic when their relations have to be inferred from the propositional content of the arguments In HDRB, the PDTB pragmatic senses are replaced with a uniform three-way classification “epistemic”, “speech-act”, and “propositional”

37. December 2009, ICONHDRB, Umangi et al.37 Uniform treatment of pragmatic relations Epistemic and speech-act inferences based on Sweetser’s (Sweetser, 1990) analysis of polysemous connectives in terms of conceptual domains Epistemic interpretation obtained when the relation involves a conclusion (expressed in one argument) based on some observation (expressed in the other argument) – “John loved Mary, because he came back” Speech-act interpretations obtain when the relation is between a speech-act and the speaker’s justification for performing it – “What are you doing tonight, because there’s a good movie on.” In both, the relation is a pragmatic one, since they involve the inference of a modality-epistemic (e.g., conclude(speaker, X)) or a speech-act (e.g., ask(speaker, X)) - that takes scope over the propositional content of one of the arguments (X)

38. December 2009, ICONHDRB, Umangi et al.38 Uniform treatment of pragmatic relations “Propositional” inference involves the inference of a complete proposition Relation taken to hold between this inferred proposition and the propositional content of one of the arguments Example below illustrates “pragmatic concession” of the “propositional” subtype (20) [ इनमें से एक ड्राईवर ने हथियारों की जानकारी होने पर मामले से हाथ खींच लिया था.] लेकिन { अदालत ने कहा की अगर उसने उस वक्त पुलिस को सूचना दे दी होती तो विस्फोटों का षडयंत्र भी विफल हो जाता } ‘[One of the drivers denied his involvement in the issue inspite of his knowledge about the weapons]. But {the court said that had he informed the police on time, the blast could have been prevented}.’

39. December 2009, ICONHDRB, Umangi et al.39 The “Goal sense” Under the “Contingency” class, a new type “Goal” has been added Applies to relations where the situation described in one of the arguments is the goal of the situation described in the other argument (which enables the achievement of the goal) The argument describing the goal marked as Arg2, and the other argument is marked Arg1 (Ex.21) (21) सुभाष का आरोप है कि [ राजद अध्यक्ष राणा को ] इसलिए [ टिकेट देना चाहते हैं ], जिससे { चारे घोटाले में वे गवाह नहीं बन सकें.} ‘Subhash has alleged that [the RJD chief wants to give a ticket to Rana] so that {he does not become a government witness in the fodder scam trial}.’ In PDTB, “goal” subsumed by the “result” subtype Distinguishing between “cause” and “goal” has important consequences for example, in the way questions are formulated over the relation

40. December 2009, ICONHDRB, Umangi et al.40 Additional Exploration of Discourse Adverbials (22) [ दानवी लहरों के कारण अंडमान के पश्चिमी तट पर तटीय वनस्पति पूरी तरह बर्बाद हो गयी.] इसके अलावा { मूंगे के चट्टानों को भी नुक्सान हुआ है.} ‘[The coastal vegetation on the west coast of the Andaman has been completely destroyed due to wild waves]. In addition, {the coral reefs have also been damaged}.’ (23) [ राह शुरू से ही औपचारिकताओं को अनदेखी कर रहे थे.] तमाम आयल PSU के बीच ONGC अकेली ऐसी कंपनी है, जिसने चालू वित्त वर्ष के लाभ, लाभांश आदि के लिए सहमति पर हस्ताक्षर भी नहीं किये हैं. इसके अलावा { आयल PSU समीक्षा बैठक में भी बैठने से राह ने इनकार कर दिया था.} ‘[Raha was avoiding the formalities from the beginning itself.] Of all the oil PSUs, ONGC is the only company which has not even signed the agreement on the profit, loss, etc. of this fiscal year. In addition, {Raha had also refused to participate in the PSU review meeting}.’ Example 22 and 23 illustrate adjacent and non-adjacent arguments of isкalAvA, respectively

41. December 2009, ICONHDRB, Umangi et al.41 References Florian Wolf and Edward Gibson. 2005. Representing Discourse Coherence: A Corpus-Based Study in Computational Linguistics, Vol. 31, No. 2.,pp. 249-288. Lynn Carlson, Daniel Marcu, and Mary Ellen Okurowski. 2001. Building a Discourse-Tagged Corpus in the Framework of Rhetorical Structure Theory. In Proceedings of the 2nd SIGDIAL Workshop on Discourse and Dialogue, Eurospeech 2001, Denmark, September 2001. NicholasAsher. 1993. Reference to Abstract Objects in Discourse. Kluwer, Dordrecht. Rafiya Begum, Samar Husain, Arun Dhwaj, Dipti Mishra Sharma, Lakshmi Bai, and Rajeev Sangal. 2008. Dependency annotation scheme for Indian languages. In Proceedings of IJCNLP-2008. Alistair Knott. 1996. A Data-driven Methodology for Motivating a Set of Coherence Relations. Ph.D.thesis, Department of Artificial Intelligence, University of Edinburgh.

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