Low-discrepancy sequence: Difference between revisions

From formulasearchengine
Jump to navigation Jump to search
en>Wile E. Heresiarch
cut out paragraph about a different topic
Small space missing
 
(One intermediate revision by one other user not shown)
Line 1: Line 1:
A '''two-level grammar''' is a [[formal grammar]] that is used to generate another formal grammar [http://web.cs.wpi.edu/~jshutt/adapt/2level.html], such as one with an infinite rule set [http://www.metanotion.net/misc/thesis.pdf#search=%22van%20Wijngaarden%20grammar%20Algol68%20ACM%20Portal%22]. This is how a [[Van Wijngaarden grammar]] was used to specify Algol68 [http://burks.bton.ac.uk/burks/language/other/a68rr/rrtoc.htm]. A [[context free grammar]] that defines the rules for a second grammar can yield an effectively infinite set of rules for the derived grammar. This makes such two-level grammars more powerful than a single layer of context free grammar, because generative two-level grammars have actually been shown to be [[Turing complete]].<ref>Sintzoff, M. "Existence of van Wijngaarden syntax for every recursively enumerable set", Annales de la Société Scientifique de Bruxelles 2 (1967), 115-118.</ref>
Very pleased to meet you! Some of my name is Eusebio and I think it music quite good when a person will say it. As a man what I really like is conducting but I'm thinking through to starting something new. I work as an get clerk. My house is now in South Carolina and I don't plan on changing it. You is likely to find my website here: http://[http://imageshack.us/photos/circuspartypanama circuspartypanama].com<br><br>Also visit my webpage ... [http://circuspartypanama.com clash of Clans hack without survey]
 
''Two-level grammar'' can also refer to a formal grammar for a two-level [[formal language]], which is a formal language specified at two levels, for example, the levels of words and sentences.{{Citation needed|date=February 2007}}
 
==Example==
A well-known non-context-free language is
:<math>\{a^n b^n a^n | n \ge 1\}.</math>
A two-level grammar for this language is the metagrammar
:N ::= 1 | N1
:X ::= a | b
together with grammar schema
:Start ::= <math> \langle a^N \rangle\langle b^N \rangle\langle a^N \rangle </math>
:<math> \langle X^{N1} \rangle</math> ::= <math>\langle X^N \rangle X </math>
:<math> \langle X^1 \rangle</math> ::= X
 
==See also==
*[[Affix grammar]]
*[[Attribute grammar]]
*[[Van Wijngaarden grammar]]
 
==References==
<references/>
 
==External links==
* Petersson, Kent (1990), "Syntax and Semantics of Programming Languages", Draft Lecture Notes, [http://www.cs.chalmers.se/~kentp/proglang.pdf PDF text].
 
{{DEFAULTSORT:Two-Level Grammar}}
[[Category:Formal languages]]
 
 
{{compu-lang-stub}}

Latest revision as of 08:41, 24 November 2014

Very pleased to meet you! Some of my name is Eusebio and I think it music quite good when a person will say it. As a man what I really like is conducting but I'm thinking through to starting something new. I work as an get clerk. My house is now in South Carolina and I don't plan on changing it. You is likely to find my website here: http://circuspartypanama.com

Also visit my webpage ... clash of Clans hack without survey