ABSTRACT
Natural languages must be learnable. They must also be parsable and producible. These three functional demands place clear constraints on the shape of natural language. This chapter examines the relation between learnability and parsability, seeking to explore overlaps in the way each constrains language. This leaves us with the question of how learnability and the problem of language acquisition is to select a target grammar from a class of grammars based on a finite sample of sentences drawn from the language generated by the target grammar. The problem of parsability is, given a set of rules and a sentence, to find those rules that can be used to derive the sentence. Learnability research demonstrates the need for a particular set of learnability constraints within one grammatical framework. Parsability research argues that several particular locality conditions are required to faithfully model the efficiency of human sentence processing.
