Chomsky hierarchy

About: Chomsky hierarchy is a research topic. Over the lifetime, 601 publications have been published within this topic receiving 31067 citations. The topic is also known as: Chomsky–Schützenberger hierarchy.

Evidence for Classifying Metathesis Patterns as Subsequential

Abstract: This paper presents a computational analysis of metathesis patterns that distinguishes three categories of metathesis that differ in their computational complexity. These categories are local metathesis, bounded long distance metathesis, and unbounded long distance metathesis. Using the formalism of finite state automata, it is established that the first two categories are subsequential, while the third category is not (in fact, it is not even regular). These terms will be discussed in more detail below, but the overall distinction is one of complexity: the subsequential class is more restrictive than the regular class. Assigning a pattern to the subsequential class then identifies it as less complex than a pattern that is non-regular. Furthermore, the patterns identified as subsequential are robustly attested in the world’s languages, whereas the non-regular patterns are much less common and in fact only attested diachronically. Thus this result suggests an upper bound for how complex a synchronic phonological pattern can be. The outline of this paper is as follows. Section 2 presents the Chomsky Hierarchy of language patterns and discusses recent findings and hypotheses for where to classifying phonological patterns on the hierarchy. Section 3 defines subsequential FSTs and demonstrates how they can be used to describe phonological patterns. Section 4 presents the computational analysis of metathesis patterns. Section 5 discusses the typological implications of the analysis, as well as the implications for learning. Section 6 indicates directions for future work and concludes. 2. The Chomsky Hierarchy and the Subregular Hypothesis Chomsky (1956) presents a means to classify languages and language patterns based on their degree of complexity or how expressive they are. This hierarchy is shown in Figure 1.

“Structural connections” in formal languages

Abstract: This paper defines the concept of “structural connection” in a mechanical language in an attempt to classify various formal languages according to the complexity of parsing structures on strings in the languages. Languages discussed vary in complexity from those with essentially no structure at all to languages which are self-defining. The relationship between some existing recognition techniques for several language classes is examined, as well as implications of language structure on the complexity of automatic recognizers.