Tree-adjoining grammar

About: Tree-adjoining grammar is a research topic. Over the lifetime, 2491 publications have been published within this topic receiving 57813 citations.

Shape Grammars: Five Questions:

Abstract: In the paper “Shape grammars: six types”, the issue of decidability in relation to shape grammars was introduced. Decidability concerns, first, the identification of different types of grammars, and, second, the answerability or solvability of questions about these types of grammars. The first of these two topics was explored in “Six types”. Six different types of shape grammars were defined in terms of different restrictions on rule format and rule ordering. The generative power, practicality, pedagogical value, and other characteristics of each type of shape grammars were discussed. In this paper, the second of the two topics in decidability is addressed. Five questions about the different types of shape grammars defined in “Six types” are posed. These questions are formulated for their practical value in design applications of shape grammars, as well as their theoretical interest. The answerability of each question is examined in detail for each type of shape grammar.

Graph-controlled grammars as language acceptors

Abstract: In this paper, we study the concept of accepting grammars within various forms of regulated grammars like programmed grammars, matrix (set) grammars, grammars with regular (set) control, periodically time-variant grammars as variants of grammars controlled by bi-coloured digraphs. We focus on their descriptive capacity. In this way, we continue our studies of accepting grammars 1, 2, 3, 11, 13, 14, 15]. Periodically time-variant grammars yield the rst example of a non-trivial equivalence of generating and accepting mode in the absence of appearance checkings. Supported by Deutsche Forschungsgemeinschaft grant DFG La 618/3-1.

An overview of conjunctive grammars

Abstract: Conjunctive grammars were introduced in 2000 as a generalization ofcontext-free grammars that allows the use of an explicit intersection oper-ation in rules. Several theoretical results on their properties have been ob-tained since then, and a number of efficient parsing algorith ms that justifythe practical value of the concept have been developed. This article reviewsthese results and proposes numerous open problems. 1 Introduction The generative power of context-free grammars is generallyconsidered to beinsufficient for denoting many languages that arise in pract ice: it has often beenobserved that all natural languages contain non-context-free constructs, whilethe non-context-freeness of programming languages was proved already in early1960s. A review of several widely different subject areas led the authors of [5] tothe noteworthy conclusion that “the world seems to be non-context-free”.This leaves the aforementioned world with the question of fin ding an ade-quate tool for denoting formal languages. As the descriptive means of context-free grammars are not sufficient but necessary for practical use, the attemptsat developing new generative devices have usually been made by generalizingcontext-free grammars in this or that way. However, most of the time an exten-sion that appears to be minorleads to a substantialincrease in the generative power(context-sensitive and indexed grammars being good examples), which is usuallyaccompanied by strong and very undesirable complexity hardness results. Theability to encode hard problems makes a formalism, in effect, a peculiar low-levelprogramming language, where writing a grammar resembles coding in assembly