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L01 CPG: Postpositions & karaka mapping Grammar for Indian Languages Properties of Indian langauges: - Relatively free word order - Rich system of case endings and post position markers - Shared constructions, vocabulory, conventions etc. No suitable existing computational grammar formalism. --------------------- Postposition/Case Important Postpositions or case important in determining semantic roles (who-gave-what-to-whom). - In Hindi: postpositions: -ne, -ko etc. - In Telugu: case-endings: -uDu (in rAmuDu) Hindi examples: - laDake ne laDakI ko phUla diyA. (boy -ne girl -ko flower -0 gave) The boy gave a flower to the girl. Relatively free word order: - laDakI ko laDake ne phUla diyA. - phUla laDake ne laDakI ko diyA. --------------------- Vibhakti to Karaka Mapping For verb 'de' (give):: Vibhakti: Karaka role - ne: karta (like agent thematic role) - ko: sampradana (like beneficiary) - 0: karma (like patient) Above is called KARAKA CHART --------------------- Problem: Above Mapping Does Not Work - laDakA laDakI ko phUla de rahA hE (boy-0 girl -ko flower-0 give -ing is The boy is giving a flower to the girl. - laDake ko phUla denA paDA (give had-to) The boy had to give a flower. - laDake se phUla diyA nahIM gayA (give not could) The boy could not give the flower. ---------------------------- Solving Problem: Vital Observations - Mapping depends on: * Verbal ending or verbal vibhakti * Also called TAM - tense-aspect-modality + Ex.: laDake ko phUla denA paDA -- ------- * When TAM is 'nA_paDA', karta is marked by 'ko' + Ex.: laDake se phUla diyA gayA -- ------- * When TAM is 'yA_gayA', karta is marked by 'se' - Mapping changes in systamatic ways when verbal ending or TAM changes. That is: * For all verbs, TAM 'nA_paDA' makes karta vibhakti to 'ko' * For all verbs, TAM 'yA_gayA' makes karta vibhakti to 'se' + Try with example verbs: dekhA (saw), piyA (drink) --------------------------- Framing a Linguistic Rule - Choose one TAM as base (say, habitual present) * Give the karaka chart for the verb class - Give rules for changing the karaka chart for other TAMs (verbal endings) * Karaka chart transformation --------------------------- Base Karaka Chart for a Verbal Root Karaka chart for a verbal root: Specify for the chosen ending (habitual past) the following: - mandatory and optional karakas - vibhakti associated with resp. nominals For a different verbal ending (different TAM): o basic karaka chart is transformed o depending on the verb-form ---------------------------- Mapping between Vibhakti & Karaka Level Karaka chart for de[tA] (give[habit.]) karaka necessity vibhakti - karta mandatory(m) 0 - karma m 0 - sampradan m ko - karana opt se -------------------------- Karaka Chart Transformation Based on TAM (tense-aspect-modality) labels TAM label karaka chart transformation + _yA karta.vibhakti:= ne + _na_paDA karta.vibhakti:= ko + _yA_gayA karta.vibhakti:= se The transformation is: - independent of verbal root - depends on TAM only..........................................NEXT PREVIOUS INDEX