Assign Case

Case marking of the arguments of the verb (i.e. Subject, Objects, and Adjuncts) is somewhat tricky, mainly because of a phenomenon known as Split Ergativity that adds some complexity. The Subject of a Clause is assigned the Ergative Case (appears as the suffix –ne on the Subject) if the verb is Finite, and either Transitive or Ditransitive, and has a Past Perfective Aspect (for e.g., ‘the lawyer advised the man’ has Ergative Case but not ‘the lawyer advises the man’). In other cases, the well-known Nominative-Accusative Case rules are applicable. However, this is an incomplete definition of the rules governing the assignment of Ergative Case; things are more complicated.

Applying Case assignment rules to the inner clause, we determine that the Object (‘the man’) has ABS Case (a passive sentence has no Grammatical Subject; its Object is assigned the Absolutive Case), and both the Preposition Phrases ‘by the dog' and 'in the park’ have OBL Case ('Oblique' indicates indirect assignment of Case by the verb). For the outer clause, we determine that the Subject (‘the lawyer’) has ERG Case, the Direct Object (‘that man’) has ACC Case, and the Adjunct (‘not to sue the city’) has OBL Case. The Object of the adjunct clause ('the city') has ABS Case, and the derived Preposition Phrase (‘suit on’) has OBL Case.

Now, Noun Phrases must be inflected for Number, Gender, and Case. Modifiers of the Noun (such as Determiners, Quantifiers, Adjectives) also require inflection for Gender and Number (for e.g., ‘vah AdmI’ is transformed to ‘us AdmI-ko’ because of ACC Case). While information on Number is available from the Deep Parser, Gender is language-specific. The Animacy feature of a Noun is also required, both for word sense disambiguation as well as for Case assignment.

The Noun Phrase complement of a Preposition Phrase (i.e. the Noun Phrase ‘the dog’ is the complement in the Prepositional Phrase ‘by the dog’) must also be inflected when the postposition phrase is assigned Case (for e.g., ‘kuttA dwArA’ is transformed to ‘kutte dwArA’). Some postpositions (notably 'of') are also inflected for the Gender of the Noun Phrase complement (for e.g., ‘kI salAh’), but with some exceptions.