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Topic: Pushdown automaton


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In the News (Tue 23 Apr 19)

  
  PlanetMath: automaton
An automaton is a general term for any formal model of computation.
Any context-free language may be represented by a pushdown automaton, and any regular language can be represented by a deterministic or non-deterministic finite automaton.
This is version 4 of automaton, born on 2002-02-23, modified 2002-05-24.
planetmath.org /encyclopedia/Automaton.html   (363 words)

  
 PlanetMath: non-deterministic pushdown automaton
A non-deterministic pushdown automaton (or PDA) is a variation on the idea of a non-deterministic finite automaton (NDFA).
Formally defined, a non-deterministic pushdown automaton is a 6-tuple
This is version 4 of non-deterministic pushdown automaton, born on 2002-02-24, modified 2003-07-25.
planetmath.org /encyclopedia/PushdownAutomaton.html   (390 words)

  
 [No title]
Similarly, the class of relations computable by pushdown transducers is not closed under intersection with the relations computable by finite-state transducers.
Consequently, the class of the languages that deterministic pushdown automata accept is not closed under intersection.
The closure under complementation of the class of the languages that deterministic pushdown automata accept, the nonclosure of the class under intersection, and DeMorgan's law all imply the nonclosure of the class under union.
www.cse.ohio-state.edu /~gurari/theory-bk/theory-bk-threese5.html   (1056 words)

  
 Pushdown automaton - Wikipedia, the free encyclopedia
Pushdown automata choose a transition by indexing a table by input signal, current state, and the top of the stack.
For every context-free grammar, there exists a pushdown automaton such that the language generated by the grammar is identical with the language generated by the automaton.
Conversely, for every pushdown automaton there exists a context-free grammar such that the language generated by the automaton is identical with the language generated by the grammar.
en.wikipedia.org /wiki/Pushdown_automaton   (691 words)

  
 LANGUAGES, GRAMMARS, AUTOMATA & QUANTUM ANALOGS
Automaton An automaton is the heart of a sequential machine, that which deals only with inputs and states.
It is defined as a sextuplet as for a nondeterministic automaton with the condition that for any q in Q and a in I, there is a unique q' such that d(q, a, q') = 1 Pushdown Automaton is an automaton equipped with a potentially infinite amount of memory in a (LIFO) stack.
And part of the definition of a push down automaton is a symmetry requirement on the transition relation H to the effect that if (q, v) → (r, vs) on a word z then (q, v') → (r, v's) on the word z for all other stack words v'.
graham.main.nc.us /~bhammel/MATH/autom.html   (4505 words)

  
 Pushdown automaton   (Site not responding. Last check: 2007-10-08)
Informally a pushdown automaton is a finite automaton outfitted with access to a potentially amount of memory in the form of single stack.
The finite automaton in question is nondeterministic (resulting in a nondeterministic pushdown automaton NPDA) since deterministic pushdown automata cannot recognize context-free languages.
A linear bounded automaton is a which is more powerful than a pushdown but less so than a Turing machine.
www.freeglossary.com /Pushdown_automaton   (581 words)

  
 Declarator Parsing in Elsa
Quick pushdown automaton refresher: A pushdown automaton is like a finite automaton, transitioning from state to state as it consumes input.
As demonstrated by this example, a pushdown automaton is more powerful than a finite automaton in that it can deal with arbitrarily nested constructs.
This deterministic automaton is the core of the declarator parser mechanism.
www.cs.berkeley.edu /~smcpeak/elkhound/sources/elsa/doc/declarator.html   (1255 words)

  
 Automata Theory | World of Computer Science
At any point in time the finite-state automaton is in one state (called the current state), and responds to one symbol of its input (called the current symbol).
The pushdown automaton consists of a finite-state automaton and a pushdown stack.
The linear-bounded automaton replaces the stack of the pushdown automaton with a string of symbols called the worktape that is allowed to be only a constant factor larger than the input string.
www.bookrags.com /research/automata-theory-wcs   (1103 words)

  
 Madhusudan: Publications   (Site not responding. Last check: 2007-10-08)
The class of visibly pushdown languages has been recently defined as a subclass of context-free languages with desirable closure properties and tractable decision problems.
We study visibly pushdown games, which are games played on visibly pushdown systems where the winning condition is given by a visibly pushdown language.
We propose the class of visibly pushdown languages as embeddings of context-free languages that is rich enough to model program analysis questions and yet is tractable and robust like the class of regular languages.
www-sal.cs.uiuc.edu /~madhu/pubs.html   (2513 words)

  
 SEM - "The transition graphs of higher-order pushdown automata" - 15/11/05 - Cachan - France   (Site not responding. Last check: 2007-10-08)
Séminaire Laboratoire Spécification et Vérification http://www.lsv.ens-cachan.fr/ Mardi 15 novembre 2005, à 11 h, Salle de conférence (Pavillon des Jardins) Arnaud Carayol (IRISA) fera un exposé sur "The transition graphs of higher-order pushdown automata" Abstract: In 1964, Büchi proved that the set of stack contents reachable by a pushdown automaton is a regular set of words.
In a level 2 pushdown automaton, the stack is replaced by a stack of stacks.
We will present a notion of regularity that captures the set of stacks of stacks reachable by a higher-order pushdown automaton, as well as its algebraic and algorithmic properties.
pauillac.inria.fr /pipermail/gtlogique/2005-November/000493.html   (351 words)

  
 [No title]
The decidability of the emptiness problem for pushdown automata can be used for showing the decidability of some problems for finite-state transducers.
On the other hand, for deterministic pushdown automata and for deterministic pushdown transducers the problem is open.
However, the decidability of the emptiness problem for pushdown automata can be used to show the decidability of the uniform halting problem for deterministic pushdown automata.
www.cse.ohio-state.edu /~gurari/theory-bk/theory-bk-threese6.html   (752 words)

  
 pushdown - OneLook Dictionary Search   (Site not responding. Last check: 2007-10-08)
We found 2 dictionaries with English definitions that include the word pushdown:
Tip: Click on the first link on a line below to go directly to a page where "pushdown" is defined.
Phrases that include pushdown: pushdown automaton, deterministic pushdown automaton, pushdown automata, pushdown transducer
www.onelook.com /?w=pushdown   (93 words)

  
 5. Pushdown Automata and Context Free Languages
5.1 indicates, a pushdown automaton consists of three components: 1) an input tape, 2) a control unit and 3) a stack structure.
A (non-deterministic) finite state pushdown automaton (abbreviated PDA or, when the context is clear, an automaton) is a 7-tuple
The expected relation between pushdown automata and context-free languages is enunciated in the following theorem.
homepages.fh-regensburg.de /~zar39030/in/node6.html   (3250 words)

  
 CS420 Syllabus
Students will be able to recognize when a language is regular, and be able to design a finite automaton or regular expression for a language that is regular and use the pumping lemma to show that a language is not regular.
Students will be able to convert a nondeterministic finite automaton into a deterministic one, a regular expression into a nondeterministic finite automaton and a finite automaton into a regular expression.
Students will be able to recognize when a language is context-free, and be able to design a context-free grammar or pushdown automaton for a language that is context-free and use the pumping lemma to show that a language is not context-free.
www.cs.umb.edu /~rlt/cs420/CS420Syllabus.html   (486 words)

  
 Finite-State Machines and Pushdown Automata   (Site not responding. Last check: 2007-10-08)
 The finite-state machine (FSM) and the pushdown automaton (PDA) enjoy a special place in computer science.
The FSM has proven to be a very useful model for many practical tasks and deserves to be among the tools of every practicing computer scientist.
Because of the importance of context-free languages, we examine how they are parsed, a key step in programming language translation.
www.cs.brown.edu /~jes/book/BOOK/node10.html   (310 words)

  
 automaton - OneLook Dictionary Search
Automaton : A Glossary of Mathematical Terms [home, info]
Phrases that include automaton: cellular automaton, finite automaton, deterministic finite automaton, pushdown automaton, deterministic pushdown automaton, more...
Words similar to automaton: robot, automata, golem, zombi, zombie, more...
www.onelook.com /?w=automaton   (289 words)

  
 Graph Drawing Applet
However, the applet also allows the user to input graphs as Finite Automaton and Pushdown Automaton, and to test strings to see if they are accepted by the FA/PDA.
The graph shown above does not act as a Finite Automaton or Pushdown Automaton, since it does not have a start node or any accept nodes.
Adding the ability to construct a Finite Automaton, given the actions of the Finite Automaton (the input strings and associated accept/reject behavior).
www.cs.rpi.edu /~prestn2/paper2.html   (1269 words)

  
 [No title]
I opted to simulate pushdown automata because I felt it was the most interesting of all the automata we had learned in class.
When an automaton is saved to a file, the model is actually encoded into string form and saved as ASCII text to a file.
When the student later goes to open that automaton, the string is decoded and the model is reconstructed.
www.ccs.neu.edu /jpt/jpt_2_2/articles/SIGCSE2002/Automata.doc   (4353 words)

  
 Finite state machine - Wikipedia, the free encyclopedia
A finite state machine (FSM) or finite state automaton (plural: automata) is a model of behavior composed of states, transitions and actions.
In non-deterministic automata, there can be none or more than one transition from a given state for a given possible input.
This distinction is relevant in practice, but not in theory, as there exists an algorithm which can transform any NDFA into an equivalent DFA, although this transformation typically significantly increases the complexity of the automaton.
en.wikipedia.org /wiki/Finite_state_machine   (2065 words)

  
 JFLAP - Formal Languages and Automata Package   (Site not responding. Last check: 2007-10-08)
JFLAP is a package of graphical tools which can be used as an aid in learning the basic concepts of Formal Languages and Automata Theory.
The user draws the transition diagram of the desired automaton and, once the picture is complete, the user enters an input string and then "runs" the automaton, being able to view all the generated configurations.
The conversions are nondeterministic finite automaton (NFA) to deterministic finite automaton (DFA), DFA to minimum state DFA, NFA to regular grammar, regular grammar to NFA, nondeterministic pushdown automaton (NPDA) to context-free grammar (CFG), NFA to regular expressions, regular expressions to NFA and three algorithms for CFG to NPDA.
www.cstc.org /data/resources/72   (221 words)

  
 summary-fall01
This is important when working with Finite Automata and Pushdown Automata.
Adding the ability to generate a formal description of a finite automaton/pushdown Automaton.
This includes the set of states, start state, transition function, input alphabet, set of accept states, and (for pushdown automata) the stack alphabet.
www.cs.rpi.edu /~prestn2/summary-fall01.html   (1159 words)

  
 [No title]   (Site not responding. Last check: 2007-10-08)
Although implementing a pushdown automaton in a neural network might seem perverted, as Shimon pointed out, it still proves that neural networks have the general strength to do that - and at the same time that - if it has this power - it might not need a pushdown mechanism..
As I point out in the introduction to a 2003 paper published in Cognitive Science (see my archive), this amounts to gratuitously assuming that the neural network has the power of lambda-calculus (and therefore of the Turing Machine).
No wonder that such networks can implement pushdown automata.
kybele.psych.cornell.edu /forums/Psych530/Psych530.archive.html   (901 words)

  
 Information and Computation Bibliography   (Site not responding. Last check: 2007-10-08)
Time and tape complexity of pushdown automaton languages.
Characterizations of pushdown machines in terms of time-bounded computers.
Fast recognition of pushdown automaton and context-free languages.
theory.lcs.mit.edu /~iandc/References/ahohu1968:186.html   (155 words)

  
 Prolog for csc250   (Site not responding. Last check: 2007-10-08)
pda2 A PushDown Automaton for Even Palidromes (another way to implement the Stack)
pda3 Check if a PDA (pushdown automaton) is NPDA (nondeterministic) or DPDA (deterministic)
pda7 A Pushdown Automaton for a^m b^k c^m by Cristina Harko (Solution to Hwk10 (Ex 3.42 a), page 117)
www.anselm.edu /homepage/mmalita/culFoundProlog/index.html   (362 words)

  
 pushdown automaton   (Site not responding. Last check: 2007-10-08)
Definition: A restricted Turing machine where the tape acts as a pushdown store (or stack, where only the latest element can be read), with an extra one-way read-only input tape.
Note: From Algorithms and Theory of Computation Handbook, page 24-19, Copyright © 1999 by CRC Press LLC.
Algorithms and Theory of Computation Handbook, CRC Press LLC, 1999, "pushdown automaton", in Dictionary of Algorithms and Data Structures [online], Paul E. Black, ed., U.S. National Institute of Standards and Technology.
www.nist.gov /dads/HTML/pushdownautm.html   (128 words)

  
 Hexapedia - Pushdown automaton (via CobWeb/3.1 planetlab2.cs.umd.edu)   (Site not responding. Last check: 2007-10-08)
Informally, a pushdown automaton is a finite automaton outfitted with access to a potentially unlimited amount of memory in the form of a single stack.
The finite automaton in question is usually a Nondeterministic finite state machine (resulting in a nondeterministic pushdown automaton or NPDA) since deterministic pushdown automata cannot recognize all context-free languages.
If we allow a finite automaton access to two stacks instead of just one, we obtain a more powerful device - equivalent in power to a Turing machine.
www.hexafind.com.cob-web.org:8888 /encyclopedia/pushdown_automaton   (273 words)

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