Finite State Temporality and Context-Free Languages
نویسندگان
چکیده
In the finite-state temporality approach, events in natural language semantics have been characterized in regular languages, with strings representing sequences of temporal observations. We extend this approach to natural language constructions which are not regular. Context-free constructions are detailed and discussed. Superposition, the key operator in the finite-state temporality approach is investigated for context-free languages. The set of context-free languages is found to not be closed under superposition. However, as with intersection, the superposition of a context-free language and a regular language results in a context-free language. Previous work on subsumption and entailment is inapplicable to context-free languages, due to the undecidability of the subset relation for context-free languages.
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