A Preliminary Work on Causative Verbs in Hindi Rafiya Begum, Dipti Misra Sharma Language Technologies Research Centre, IIIT. [email protected], [email protected] Abstract Causative verbs are differently realized in dif- ferent languages. These verbs have been an in- teresting area of study. The study of causative This paper introduces a preliminary constructions is important as it involves the in- work on Hindi causative verbs: their teraction of various components such as seman- classification, a linguistic model for tics, syntax and morphology (Comrie, 1981). their classification and their verb This paper presents the preliminary work on frames. The main objective of this work Hindi causative verbs. is to come up with a classification of the Hindi causative verbs. In the classifica- 2 Causative Verbs tion we show how different types of Hindi verbs have different types of Causative verbs mean that some actor makes causative forms. It will be a linguistic somebody else do something or causes him to be resource for Hindi causative verbs in a certain state (Agnihotri, 2007). The causal which can be used in various NLP ap- verb indicates the causing of another to do plications. This resource enriches the al- something, instead of doing it oneself (Greaves, ready available linguistic resource on 1983). Semantically causative verbs refer to a Hindi verb frames (Begum et al., causative situation which has two components: 2008b). This resource will be helpful in (a) the causing situation or the antecedent; (b) getting proper insight into Hindi verbs. the caused situation or the consequent. These In this paper, we present the morpholo- two combine to make a causative situation (Ne- gy, semantics and syntax of the causa- dyalkov and Silnitsky, 1973). There are differ- tive verbs. The morphology is captured ent ways in which causation is indicated in dif- by the word generation process; seman- ferent languages. There are three types of causa- tics is captured by the linguistic model tives: Morphological causatives, Periphrastic followed for classifying the verbs and causatives and Lexical causatives (Comrie, the syntax has been captured by the verb 1981). frames using relations given by Panini. Morphological Causatives indicate causa- tion with the help of verbal affixes. Sanskrit, 1 Introduction Hindi/Urdu, Persian, Arabic, Hebrew, Japanese, Khmer and Finnish languages have morpholog- Verbs play a major role in expressing the mean- ical causatives. Periphrastic causatives indi- ing of a sentence and its syntactic behavior. cate causation with the help of a verb which They decide the number of participants that will occurs along with the main verb. For example, participate in the action. Semantically verbs are in English in a sentence such as: classified into action verbs, state verbs and process verbs. Syntactically they are classified (1) John made the child drink milk. into intransitives, transitives and ditransitives. The morphological, semantic and syntactic In the above example the verb make is ex- properties of verbs play an important role in pressing causation which is occurring along deeper level analysis such as parsing. with the verb drink which in turn is expressing 120 Proceedings of the 8th Workshop on Asian Language Resources, pages 120–128, Beijing, China, 21-22 August 2010. c 2010 Asian Federation for Natural Language Processing the main action. English, German and French transitive verb becomes the patient and the are some of the languages which have periph- agent of the affective transitive verbs becomes rastic causatives. Lexical causatives are those the recipient in the first causal and they both in which there is no morphological similarity will take a ko postpositon (Hindi case marker). between the base verb root and the causative Effective verbs and ditransitive verbs have only verb form. A different lexical item is used to one causal form. The agent of the effective verb indicate causation. For example, the causative and ditransitive verb becomes the causative of English eat is feed. English and Japanese agent in the first causal. So this causative agent have lexical causatives. English has both pe- in the first causal takes a se ‘with’ postposition riphrastic and lexical causatives. (Hindi case marker). Verbs belonging to karnaa ‘to do’ class come under the effective verbs. 3 Causative verbs in Hindi The major studies in Hindi causatives: Kach- ru (1966), Kachru (1980), Kachru (2006), Causatives in Hindi are realized through a mor- McGregor (1995), Greaves (1983), Kellogg phological process. In Hindi, a base verb root (1972), Agnihotri (2007), Sahaay (2004), Sa- changes to a causative verb when affixed by haay (2007), Singh (1997) and Tripathi (1986). either an ‘-aa’ or a ‘-vaa’ suffix. Kachru (1966) has given the classification of Hindi verbs based on their causativization beha- Base verb First causal Second causal vior. The others have mostly talked about the so sul-aa sul-vaa derivation process of the causative verbs. ‘sleep’ ‘put to sleep’ ‘cause to put to However the classification of causative verbs sleep’ in Hindi remains an issue of discussion. Since they are morphologically related, the decision of In each step of causative derivation there is what is the base verb form of these verbs re- an increase in the valency of the verb (Kachru, mains a point of discussion. There are two ap- 2006; Comrie, 1981) proaches which are followed in deciding the base verb: (1) causative formation based only (2) baccaa soyaa on morphology, (2) causative formation based child sleep.Pst on morphology and semantics. ‘The child slept.’ I.Based on Morphology aayaa ne bacce ko sulaayaa (3) maid Erg. child Acc. sleep.Caus.Pst Base verb First causal Second causal ‘The maid put the child to sleep.’ (Intransitive) (Transitive) (Causative) khul khol khulvaa (4) maa.N ne aayaa se bacce ko ‘open’ ‘open’ ‘cause to open’ mother Erg. maid by child Acc. sulvaayaa II. Based on Morphology and Semantics sleep.Caus.Pst ‘Mother caused the maid to put the child to Intransitive Base verb Second causal sleep.’ (Intransitive) (Transitive) (Causative) khul khol khulvaa Hindi verbs are divided into two groups ‘open’ ‘open’ ‘cause to open’ based on their behaviour in causative sentences: affective verbs and effective verbs (Kachru, In I, khul ‘open’ is taken as the base verb and 2006). The action of affective verbs benefits or khol ‘open’ and khulvaa ‘cause to open’ are de- affects the agent. Affective verbs will have both rived from it by adding suffix ‘-aa’ and ‘-vaa’ first and second causal forms. Verbs such as respectively to the base verb (Kachru, 1966; ronaa ‘to cry’ and dau.Dnaa ‘to run’ are affec- Kachru, 1980). The arrow denotes the direction tive intransitive verbs. Only verbs belonging to khaanaa ‘to eat’ class come under affective of derivation from base verb. Here, the forward arrow denotes the increment of the argument transitive verbs. The agent of the affective in- from base to the causal forms. On the other 121 hand, in II, khol ‘open’ is taken as the base verb. door open.Pst Here, other than morphology, the semantics of ‘Door opened.’ the verbs is also taken into consideration. Here khul ‘open’ and khulvaa ‘cause to open’ are de- (6) raam ne darvaazaa kholaa rived from the base verb khol ‘open’. khulvaa ram Erg. door open.Pst ‘cause to open’ is a causative verb which is de- ‘Ram opened the door.’ rived from the base verb by adding suffix ‘-vaa’ to it. khul ‘open’ is a derived intransitive form. (7) maiM ne raam se darvaazaa The agent of the base verb khol ‘open’ is not I Erg. ram by door realized on the surface level of the derived in- khulvaayaa transitive verb khul ‘open’ though it is implied open.Caus.Pst semantically. Here there is both forward and ‘I made Ram open the door.’ backward derivation. From base verb to the de- rived intransitive it is a backward derivation When we come to the causatives, the notion which means there is a reduction of one argu- of prayojak karta ‘causer’, prayojya karta ment from base verb to the derived intransitive ‘causee’ and madhyastha karta ‘mediator verb (Tripathi, 1986; Reinhart, 2005). causer’ are introduced. prayojak karta ‘causer’ In this paper, we motivate our work by pre- is the initiator of the action. prayojya karta senting our approach for classifying the causa- ‘causee’ is the one who is made to do the action tive verbs in Hindi. by the prayojak karta ‘causer’. madhyasta karta ‘mediator causer’ is the causative agent of the 4 Our Approach action. The karta of the base verb becomes the prayojya karta of the causative verb and the 4.1 Linguistic Model for Classifying Caus- prayojak karta of the first causative becomes ative verbs the madhyasta karta of the second causative. We have followed Paninian Grammatical This model takes both semantics and framework in this model as the theoretical basis morphology into consideration. for our approach. The meaning of every verbal root (dhaatu) consists of: (a) activity (vyaapaa- 4.1.1 Semantics ra) and; (b) result (phala). Activity denotes the (8) caabii ne taalaa kholaa actions carried out by the various participants key Erg lock open.Pst (karakas) involved in the action. Result denotes ‘The key opened the lock.’ the state that is reached, when the action is completed (Bharati et al., 1995). The partici- (9)* raam ne caabii se taalaa khulvaayaa pants of the action expressed by the verb root ram Erg. key by lock open.Caus.Pst are called karakas. There are six basic karakas, ‘Ram caused the key to open the lock.’ namely; adhikarana ‘location’, apaadaan ‘source’, sampradaan ‘recipient’, karana ‘in- (10)raam ne mohan dvaaraa caabii se taalaa strument’, karma ‘theme’ and karta ‘agent’ ram Erg. mohan by key with lock (Begum et al., 2008a).