Rule-Blocking and Forward-Looking Conditions in the Computational Modelling of Pāṇinian Derivation

Attempting to model Pāṇinian procedure computationally forces one to clarify concepts explicitly and allows one to test various versions and interpretations of his grammar against each other and against bodies of extant Sanskrit texts. To model Pāṇinian procedure requires creating data structures and a framework that allow one to approximate the statement of Pāṇinian rules in an executable language. Scharf (2009: 117-125) provided a few examples of how rules would be formulated in a computational model of Pāṇinian grammar as opposed to in software that generated speech forms without regard to Pāṇinian procedure. Mishra (2009) described the extensive use of attributes to track classification, marking and other features of phonetic strings. Goyal, Kulkarni, and Behera (2009, especially sec. 3.5) implemented a model of the asiddhavat section of rules (6.4.22-129) in which the state of the data passed to rules of the section is maintained unchanged and is utilized by those rules as conditions, yet the rules of the section are applied in parallel, and the result of all applicable rules applying exits the section. The current paper describes Scharf and Hyman’s implementation of rule blocking and forward-looking conditions. The former deals with complex groups of rules concerned with domains included within the scope of a general rule. The latter concerns a case where a decision at an early stage in the derivation requires evaluation of conditions that do not obtain until a subsequent stage in the derivation.