Various Types of Comet Languages and their Application in External Contextual Grammars

TL;DR

This paper explores various comet-like language families within regular languages, comparing their properties and hierarchies, and extends the understanding of external contextual grammars by introducing new language families.

Contribution

It introduces and compares new comet-like language families within regular languages, extending the hierarchy of external contextual grammars.

Findings

Extended the hierarchy of external contextual grammars.

Compared comet-like language families with other subregular families.

Identified relationships and differences among various language families.

Abstract

In this paper, we continue the research on the power of contextual grammars with selection languages from subfamilies of the family of regular languages. We investigate various comet-like types of languages and compare such language families to some other subregular families of languages (finite, monoidal, nilpotent, combinational, (symmetric) definite, ordered, non-counting, power-separating, suffix-closed, commutative, circular, or union-free languages). Further, we compare the language families defined by these types for the selection with each other and with the families of the hierarchy obtained for external contextual grammars. In this way, we extend the existing hierarchy by new language families.