en>Jodosma: spelling: dimentional→dimensional

2014-10-18T00:26:55Z

spelling: dimentional→dimensional

115.64.131.124: /* Overview */

2013-03-29T21:33:17Z

Overview

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	http://~~architectepartners~~.com/<br>[http://~~architectepartners~~.com/ ~~architecte à Marrakech~~]		A '''queue machine''' or '''queue automaton''' is a [[finite state machine]] with the ability to store and retrieve data from an infinite-memory [[queue (data structure)\|queue]]. It is a model of computation equivalent to a [[Turing machine]], and therefore it can process any [[formal language]].

			== Theory ==
			We define a queue machine by the six-tuple

			:<math>M = (Q, \Sigma, \Gamma, \$, s, \delta)</math> where

			* <math>\,Q</math> is a finite set of ''states'';
			* <math>\,\Sigma \subset \Gamma</math> is the finite set of the ''input alphabet'';
			* <math>\,\Gamma</math> is the finite ''queue alphabet'';
			* <math>\,\$ \in \Gamma - \Sigma</math> is the ''initial queue symbol'';
			* <math>\,s \in Q</math> is the ''start state'';
			* <math>\,\delta : Q \times \Gamma \rightarrow Q \times \Gamma^*</math> is the ''transition function''.

			We define the current status of the machine by a ''configuration'', an ordered pair of its state and queue contents <math>\,(q,\gamma)\in Q\times\Gamma^</math> (note <math>\,\Gamma^</math> defines the [[Kleene closure]] or set of all supersets of <math>\,\Gamma</math>). The starting configuration on an input string <math>\,x</math> is defined as <math>\,(s,x\$)</math>, and the transition <math>\rightarrow_M^1</math> from one configuration to the next is defined as:

			:<math>\,(p,A\alpha) \rightarrow_M^1 (q,\alpha\gamma)</math>

			where <math>A</math> is a symbol from the queue alphabet, <math>\alpha</math> is a sequence of queue symbols (<math>\alpha \in \Gamma^*</math>), and <math>(q, \gamma) = \delta(p, A)</math>. Note the "first-in-first-out" property of the queue in the relation.

			The machine accepts a string <math>\,x\in\Sigma^</math> if after a (possibly infinite) number of transitions the starting configuration evolves to exhaust the string (reaching a null string <math>\,\epsilon</math>), or <math>\,(s,x\$)\rightarrow_M^(q,\epsilon).</math><ref>{{cite book \|last=Kozen \|first=Dexter C. \|editor=David Gries, Fred B. Schneider \|title=Automata and Computability \|origyear=1951 \|format=hardcover \|edition=1 \|series=Undergraduate Texts in Computer Science \|year=1997 \|publisher=Springer-Verlag \|location=New York \|isbn=0-387-94907-0 \|pages=368–370}}</ref>

			=== Turing completeness ===
			We can prove that a queue machine is equivalent to a Turing machine by showing that a queue machine can simulate a Turing machine and vice-versa.

			A Turing machine can be simulated by a queue machine that keeps a copy of the Turing machine's contents in its queue at all times, with two special markers: one for the TM's head position, and one for the end of the tape; its transitions simulate those of the TM by running through the whole queue, popping off each of its symbols and re-enqueing either the popped symbol, or, near the head position, the equivalent of the TM transition's effect.

			A queue machine can be simulated by a Turing machine, but more easily by a [[multi-tape Turing machine]], which is known to be equivalent to a normal single-tape machine.
			The simulating queue machine reads input on one tape and stores the queue on the second, with pushes and pops defined by simple transitions to the beginning and end symbols of the tape.<ref>{{cite web \|url=http://www.cs.uiowa.edu/~rus/Courses/Theory/Notes/turing3.pdf \|title=Variants of Turing Machines \|accessdate=2007-11-06 \|last=Rus \|first=Teodor \|date= \|work=Lecture Notes Covering Theory of Computation \|publisher=University of Iowa, Iowa City, IA, 52242-1419}}</ref> A formal proof of this is often an exercise in theoretical computer science courses.

			== Applications ==
			Queue machines offer a simple model on which to base [[computer architectures]],<ref>{{cite journal \|last=Feller \|first=M. \|coauthors=M.D. Ercegovac \|year=1981 \|title=Queue machines: An organization for parallel computation \|journal=Lecture Notes in Computer Science \|volume= 111\|issue= \|pages= 37\|id= \|url=http://www.springerlink.com/content/m8w6x22741k5u093/ \|accessdate=2007-11-06 \|doi=10.1007/BFb0105108}}</ref><ref>{{cite journal \|last=Schmit \|first=Herman \|authorlink= \|coauthors=Benjamin Levine, Benjamin Ylvisaker \|year= 2002\|month= \|title=Queue Machines: Hardware Compilation in Hardware \|journal=10th Annual IEEE Symposium on Field-Programmable Custom Computing Machines (FCCM'02) \|volume= \|issue= \|pages=152 \|id= \|url=http://doi.ieeecomputersociety.org/10.1109/FPGA.2002.1106670 \|accessdate=2007-11-06\|doi=10.1109/FPGA.2002.1106670}}</ref> [[programming languages]], or [[algorithms]].<ref>{{cite web \|url=http://algo.inria.fr/seminars/sem99-00/moore1.html \|title=Queues, Stacks, and Transcendentality at the Transition to Chaos \|accessdate=2007-11-06 \|last=Moore \|first=Christopher \|coauthors= \|date=1999-09-20 \|work=Algorithms Project's Seminar \|publisher=INRIA}}</ref><ref>{{cite web \|url=http://www.latrobe.edu.au/philosophy/phimvt/misc/queue.html \|title=A queue machine for evaluating expressions \|accessdate=2007-11-06 \|last=von Thum \|first=Manfred \|year=2007 \|publisher=LaTrobe University}}</ref>

			== See also ==
			* [[Computability]]
			* [[Turing machine equivalents]]
			* [[Deterministic finite automaton]]
			* [[Pushdown automaton]]
			* [[Tag system]]
			* [http://pleasingfungus.com/#Manufactoria Manufactoria], a browser flash game tasking the player with implementation of various algorithms using a queue machine model.

			== References ==
			{{reflist}}

			{{DEFAULTSORT:Queue Machine}}
			[[Category:Automata theory]]

130.127.255.228 at 01:38, 26 January 2011

2011-01-26T01:38:33Z

New page

http://architectepartners.com/<br>[http://architectepartners.com/ architecte à Marrakech]

Classification of manifolds - Revision history

en>Jodosma: spelling: dimentional→dimensional

115.64.131.124: /* Overview */

130.127.255.228 at 01:38, 26 January 2011