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Nulls in PropBank

Nulls in PropBank. Sep 17 th 2010. What is a null category. PropBank annotation. Shyam ne khana khaaya Annotate Arguments of the verb ` Khaa ’ Shyam and khana What if someone asks- kisne khaana khaaya ? Shyam ne khaaya Shyam ne * khaana * khaaya (Object dropped)

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Nulls in PropBank

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  1. Nulls in PropBank Sep 17th2010

  2. What is a null category

  3. PropBank annotation • Shyam ne khanakhaaya • Annotate Arguments of the verb `Khaa’ • Shyam and khana • What if someone asks- kisnekhaanakhaaya? • Shyam ne khaaya • Shyam ne *khaana* khaaya (Object dropped) • What about: tumne Ram kokaunsikitaabdi? • Nilikitaabraamkodi • *maine* nilikitaabraamkodi (Subject dropped)

  4. Missing information! • Same verb, but varying number of arguments: • Ram ne khaanakhaaya • Ram ne *khaana* khaaya • No consistency in the representation of the verb `khaana’ • Hence, we need to insert missing arguments, or as they are also known ‘Empty Categories (EC)’

  5. Which missing arguments? • Only the obligatory arguments of the verb • Khaa requires two arguments- eater and thing eaten • When we ask a question: Ram ne kyakhaaya? • It becomes possible to drop Ram & respond by saying: khaanakhaaya • Ram is old information and is not repeated • If obligatory arguments are missing, the correct argument structure of a verb will not be understood by the machine

  6. That’s great!

  7. Fourcategories of EC • pro • PRO • GAP-pro • RELPRO

  8. pro • Missing subject and object e.g responding to a question • *pro* mujheharikodenaahai • Kisnedarvaazakholaa? Mohan ne *pro* kholaa • Dropped subject in a sentence • Bacchonkeliyekaryakramaayojankarnahogaa

  9. pro characteristics • Fewer surface cues • Requires knowledge of the verb’s obligatory arguments

  10. pro is the missing VIP!

  11. PRO • When a sentence has an embedded clause with a non-finite verb AND the same (missing) subject as the main clause, we get *PRO* • Note two important points: • Mohanine [*PRO*ikitaabpaRnii] caahi • [Khaanakhaana] has the verb `khaana’ in non-finite form i.e it’s not showing agreement or tense info • We coindex the PRO with Mohan • There are exceptions!!

  12. For PRO cases, the verb is non-finite, and handicapped!

  13. Exceptions to PRO • Not present for the modals e.g • RaamkogharjaanapaDaa / caahiye • Raamkogharjaanediyaa • Verbs with lagnaa (more of a helping verb) • Raamnaachnelagaa • Not in location information type sentences • Ram gharjaane se pehlevahanrukaa

  14. PRO characteristics • भारतसर्कारने [ऐसाकरनेसे] इंकारकरदिया The verb ends withना, नी, ने It has a corresponding argument to coindex with! If you replace it with an actual word, it sounds ungrammatical

  15. GAP PRO • Only in co-ordinate clauses!!! • Clauses joined by और, या or a comma • mohan-neikitaabpaRh-ii aur [*GAP-pro*]i so ga-yaa • Note that we only look for missing arguments in co-ordination structures • We also coindexlike the *PRO*

  16. GAP-PRO only found with co-ordination!

  17. Context for RELPRO (1) phooljodaaliyon par khile hue hai, ache hai • (1) is an example of a relative clause • phool is the noun that’s getting modified • In a relative clause, there’s always an embedded ‘modifier’ clause inside the main clause • phool [jodaaliyon par khile hue hai], ache hai

  18. Upside down clause • In the case of participial relatives, the order of elements in the relative clause is flipped • [daaliyon par khile] phool ache hai • The embedded clause is before the element being modified • Also, there is no relative pronoun ‘jo’ like we can see in (1) • In such conditions, we will insert a missing subject argument in the upside down clause • (2) [*RELPRO*daaliyon par khile hue] phool ache hai

  19. RELPROcharacteristics • इससे [तटोंपररहनेवाले] जिवजंतुओंकोभीनुकसानहोगा Participial verbs can be identified by -ताहुआ , -नेवालेe.gकरताहुआ, करनेवाले They also have the drel nmod__k1inv or nmod__k2inv

  20. RELPRO: the upside down EC

  21. More practice!

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