Regulated Rewriting

	Regulated Rewriting Regulated rewriting is a specific area of formal languages studying grammatical systems which are able to take some kind of control over the production applied in a derivation step. For this reason, the grammatical systems studied in Regulated Rewriting theory are also called "Grammars with Controlled Derivations". Among such grammars can be noticed: Matrix Grammars Basic concepts Definition A Matrix Grammar, MG, is a four-tuple G = (N, T, M, S) where 1.- N is an alphabet of non-terminal symbols 2.- T is an alphabet of terminal symbols disjoint with N 3.- M = is a finite set of matrices, which are non-empty sequences m_ = _,...,p_/math>, with k(i)\geq 1, and 1 \leq i \leq n, where each p_ 1\leq j\leq k(i), is an ordered pair p_ = (L, R) being L \in (N \cup T)^N(N\cup T)^, R \in (N\cup T)^* these pairs are called "productions", and are denoted L\rightarrow R. In these conditions the matrices can be written down as m_i = _\rightarrow R_,...,L_\rightarrow R_/math> 4.- S is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu]
picture info	Formal Languages In logic, mathematics, computer science, and linguistics, a formal language consists of words whose letters are taken from an alphabet and are well-formed according to a specific set of rules. The alphabet of a formal language consists of symbols, letters, or tokens that concatenate into strings of the language. Each string concatenated from symbols of this alphabet is called a word, and the words that belong to a particular formal language are sometimes called ''well-formed words'' or '' well-formed formulas''. A formal language is often defined by means of a formal grammar such as a regular grammar or context-free grammar, which consists of its formation rules. In computer science, formal languages are used among others as the basis for defining the grammar of programming languages and formalized versions of subsets of natural languages in which the words of the language represent concepts that are associated with particular meanings or semantics. In computational complex ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu]
	Production (computer Science) A production or production rule in computer science is a ''rewrite rule'' specifying a symbol substitution that can be recursively performed to generate new symbol sequences. A finite set of productions P is the main component in the specification of a formal grammar (specifically a generative grammar). The other components are a finite set N of nonterminal symbols, a finite set (known as an alphabet) \Sigma of terminal symbols that is disjoint from N and a distinguished symbol S \in N that is the ''start symbol''. In an unrestricted grammar, a production is of the form u \to v, where u and v are arbitrary strings of terminals and nonterminals, and u may not be the empty string. If v is the empty string, this is denoted by the symbol \epsilon, or \lambda (rather than leave the right-hand side blank). So productions are members of the cartesian product :V^NV^ \times V^* = (V^\setminus\Sigma^) \times V^, where V := N \cup \Sigma is the ''vocabulary'', ^ is the Kleene star ... [...More Info...] [...Related Items...] OR:* [Wikipedia] [Google] [Baidu]
picture info	Context-free Grammars In formal language theory, a context-free grammar (CFG) is a formal grammar whose production rules are of the form :A\ \to\ \alpha with A a ''single'' nonterminal symbol, and \alpha a string of terminals and/or nonterminals (\alpha can be empty). A formal grammar is "context-free" if its production rules can be applied regardless of the context of a nonterminal. No matter which symbols surround it, the single nonterminal on the left hand side can always be replaced by the right hand side. This is what distinguishes it from a context-sensitive grammar. A formal grammar is essentially a set of production rules that describe all possible strings in a given formal language. Production rules are simple replacements. For example, the first rule in the picture, :\langle\text\rangle \to \langle\text\rangle = \langle\text\rangle ; replaces \langle\text\rangle with \langle\text\rangle = \langle\text\rangle ;. There can be multiple replacement rules for a given nonterminal symbol. The l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu]
picture info	Turing Machine A Turing machine is a mathematical model of computation describing an abstract machine that manipulates symbols on a strip of tape according to a table of rules. Despite the model's simplicity, it is capable of implementing any computer algorithm. The machine operates on an infinite memory tape divided into discrete cells, each of which can hold a single symbol drawn from a finite set of symbols called the alphabet of the machine. It has a "head" that, at any point in the machine's operation, is positioned over one of these cells, and a "state" selected from a finite set of states. At each step of its operation, the head reads the symbol in its cell. Then, based on the symbol and the machine's own present state, the machine writes a symbol into the same cell, and moves the head one step to the left or the right, or halts the computation. The choice of which replacement symbol to write and which direction to move is based on a finite table that specifies what to do for each com ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu]
picture info	Secaucus, New Jersey Secaucus ( ) is a town in Hudson County, New Jersey, United States. As of the 2010 United States census, the town's population was 16,264,DP-1 – Profile of General Population and Housing Characteristics: 2010 for Secaucus town, Hudson County, New Jersey , United States Census Bureau . Accessed December 25, 2011. [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu]
picture info	Formal Languages In logic, mathematics, computer science, and linguistics, a formal language consists of words whose letters are taken from an alphabet and are well-formed according to a specific set of rules. The alphabet of a formal language consists of symbols, letters, or tokens that concatenate into strings of the language. Each string concatenated from symbols of this alphabet is called a word, and the words that belong to a particular formal language are sometimes called ''well-formed words'' or '' well-formed formulas''. A formal language is often defined by means of a formal grammar such as a regular grammar or context-free grammar, which consists of its formation rules. In computer science, formal languages are used among others as the basis for defining the grammar of programming languages and formalized versions of subsets of natural languages in which the words of the language represent concepts that are associated with particular meanings or semantics. In computational complex ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu]