http://wiki.karljones.com/index.php?action=history&feed=atom&title=Pushdown_automaton
Pushdown automaton - Revision history
2026-10-23T17:49:06Z
Revision history for this page on the wiki
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http://wiki.karljones.com/index.php?title=Pushdown_automaton&diff=18825&oldid=prev
Karl Jones at 22:47, 24 September 2016
2016-09-24T22:47:44Z
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Karl Jones
http://wiki.karljones.com/index.php?title=Pushdown_automaton&diff=18824&oldid=prev
Karl Jones: /* See also */
2016-09-24T22:46:37Z
<p><span dir="auto"><span class="autocomment">See also</span></span></p>
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Karl Jones
http://wiki.karljones.com/index.php?title=Pushdown_automaton&diff=18690&oldid=prev
Karl Jones: Created page with "In computer science, a '''pushdown automaton''' (PDA) is a type of automaton that employs a stack. == Description == P..."
2016-09-22T13:44:57Z
<p>Created page with "In <a href="/index.php/Computer_science" title="Computer science">computer science</a>, a '''pushdown automaton''' (PDA) is a type of <a href="/index.php/Automata_theory" title="Automata theory">automaton</a> that employs a <a href="/index.php/Stack_(abstract_data_type)" title="Stack (abstract data type)">stack</a>. == Description == P..."</p>
<p><b>New page</b></p><div>In [[computer science]], a '''pushdown automaton''' (PDA) is a type of [[Automata theory|automaton]] that employs a [[Stack (abstract data type)|stack]].<br />
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== Description ==<br />
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Pushdown automata are used in theories about what can be computed by machines. They are more capable than finite-state machines but less capable than [[Turing machine|Turing machines]]. Deterministic pushdown automata can recognize all deterministic context-free languages while nondeterministic ones can recognize all context-free languages, with the former often used in parser design.<br />
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The term "pushdown" refers to the fact that the stack can be regarded as being "pushed down" like a tray dispenser at a cafeteria, since the operations never work on elements other than the top element. A stack automaton, by contrast, does allow access to and operations on deeper elements. Stack automata can recognize a strictly larger set of languages than pushdown automata.<br />
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A nested stack automaton allows full access, and also allows stacked values to be entire sub-stacks rather than just single finite symbols.<br />
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== See also ==<br />
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* [[Automata theory]]<br />
* [[Context-free grammar]]<br />
* [[Counter automaton]]<br />
* [[Finite automaton]]<br />
* [[Stack (abstract data type)]]<br />
* [[Stack machine]]<br />
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== External links ==<br />
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* [https://en.wikipedia.org/wiki/Pushdown_automaton Pushdown automaton] @ Wikipedia<br />
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[[Category:Computer science]]</div>
Karl Jones