Who is associated with the formulation of the hierarchy of formal grammars?

Noam Chomsky is associated with the formulation of the hierarchy of formal grammars, which is a fundamental concept in the fields of linguistics and computer science. His work in the 1950s introduced a systematic way to categorize different levels of grammars based on their generative power. This hierarchy, often referred to as the Chomsky hierarchy, includes regular grammars, context-free grammars, context-sensitive grammars, and recursively enumerable grammars.

Chomsky's contributions established a foundation for understanding how languages can be structured and generated, influencing both theoretical linguistics and practical applications such as programming languages and artificial intelligence. His theories accentuate the relationship between language structure and cognitive processes, making it easier to analyze and construct languages both naturally and artificially.

The other individuals mentioned are significant in their own right within the field of linguistics and applied linguistics, but they do not pertain to the development of the formal grammar hierarchy like Chomsky does.