10,589 research outputs found
Linear indexed languages
AbstractIn this paper one characterization of linear indexed languages based on controlling linear context-free grammars with context-free languages and one based on homomorphic images of context-free languages are given. By constructing a generator for the family of linear indexed languages, it is shown that this family is a full principal semi-AFL. Furthermore a Parikh theorem for linear indexed languages is stated which implies that there are indexed languages which are not linear
Regularly Controlled Bidirectional Linear Basic Grammars
We investigate the bidirectional application of grammar productions -- i.e., using the productions in the reversed direction too -- to linear basic grammars. As in the case of regularly controlled bidirectional context-free grammars (or RCB grammars), we provide bidirectional linear basic grammars with a regular control language over the rules (i.e., productions and their corresponding reductions). Our main result shows that under the so-called RS/B/f-mode of derivation, bidirectionality gives rise to a dramatic increase in generating power compared with (regularly controlled unidirectional) linear basic grammars.\ud
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Controlled Bidirectional Grammars
We investigate context-free grammars the rules of which can be used in a productive and in a reductive fashion, while the application of these rules is controlled by a regular language. We distinguish several modes of derivation for this kind of grammar. The resulting language families (properly) extend the family of context-free languages. We establish some closure properties of these language families and some grammatical transformations which yield a few normal forms for this type of grammar. Finally, we consider some special cases (viz. the context-free grammar is linear or left-linear), and generalizations, in particular, the use of arbitrary rather than regular control languages
Time-Bounded Controlled Bidirectional Grammars
We study regularly controlled bidirectional (RCB) grammars from the viewpoint of time-bounded grammars. RCB-grammars are context-free grammars of which the rules can be used in a productive and in a reductive fashion, while the application of these rules is controlled by a regular language. Several modes of derivation can be distinguished for this kind of grammar. A time-bound on such a grammar is a measure of its derivational complexity. For some families of time bounds and for some modes of derivation we establish closure properties and a normal form theorem. In addition parsing algorithms are given for some modes of derivation. We conclude with considering generalizations with respect to the family of control languages and the family of bounding functions
The Grail theorem prover: Type theory for syntax and semantics
As the name suggests, type-logical grammars are a grammar formalism based on
logic and type theory. From the prespective of grammar design, type-logical
grammars develop the syntactic and semantic aspects of linguistic phenomena
hand-in-hand, letting the desired semantics of an expression inform the
syntactic type and vice versa. Prototypical examples of the successful
application of type-logical grammars to the syntax-semantics interface include
coordination, quantifier scope and extraction.This chapter describes the Grail
theorem prover, a series of tools for designing and testing grammars in various
modern type-logical grammars which functions as a tool . All tools described in
this chapter are freely available
Representing a P-complete problem by small trellis automata
A restricted case of the Circuit Value Problem known as the Sequential NOR
Circuit Value Problem was recently used to obtain very succinct examples of
conjunctive grammars, Boolean grammars and language equations representing
P-complete languages (Okhotin, http://dx.doi.org/10.1007/978-3-540-74593-8_23
"A simple P-complete problem and its representations by language equations",
MCU 2007). In this paper, a new encoding of the same problem is proposed, and a
trellis automaton (one-way real-time cellular automaton) with 11 states solving
this problem is constructed
Nonterminal Separating Macro Grammars
We extend the concept of nonterminal separating (or NTS) context-free grammar to nonterminal separating -macro grammar where the mode of derivation is equal to "unrestricted". "outside-in' or "inside-out". Then we show some (partial) characterization results for these NTS -macro grammars
Generating All Permutations by Context-Free Grammars in Greibach Normal Form
We consider context-free grammars in Greibach normal form and, particularly, in Greibach -form () which generates the finite language of all strings that are permutations of different symbols (). These grammars are investigated with respect to their descriptional complexity, i.e., we determine the number of nonterminal symbols and the number of production rules of as functions of . As in the case of Chomsky normal form these descriptional complexity measures grow faster than any polynomial function
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