'Free languages' diaporamas de présentation

Turing Machines (TM)

Turing Machines (TM). Generalize the class of CFLs: Note that there are non-recursively enumerable languages. Recursively Enumerable Languages. Recursive Languages. Context-Free Languages. Regular Languages. Recursively Enumerable Languages. Recursive Languages.

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Context-Free and Noncontext-Free Languages

Context-Free and Noncontext-Free Languages. Chapter 13. Languages That Are and Are Not Context-Free. a * b * is regular. A n B n = { a n b n : n ? 0} is context-free but not regular. A n B n C n = { a n b n c n : n ? 0} is not context-free. Of Languages and Machines.

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The Post Correspondence Problem

The Post Correspondence Problem. Some undecidable problems for context-free languages:. Is ?. are context-free grammars. Is context-free grammar ambiguous?. We need a tool to prove that the previous problems for context-free languages

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More Applications of The Pumping Lemma

More Applications of The Pumping Lemma. The Pumping Lemma:. For infinite context-free language . there exists an integer such that . for any string . we can write. with lengths. and it must be:. Non-context free languages. Context-free languages. Theorem:. The language.

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Remaining Topics

Remaining Topics. Decidability Concept 4.1 The Halting Problem 4.2 P vs. NP 7.2 and 7.3 NP-completeness & Cook-Levin Theorem 7.4. Review: Turing Machines in a nutshell. Church-Turing Thesis Turing Machine equal Notion of an Algorithm Turing Machine

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Remaining Topics

Remaining Topics. Decidability Concept 4.1 The Halting Problem 4.2 P vs. NP 7.2 and 7.3 NP-completeness & Cook-Levin Theorem 7.4. Review: Turing Machines in a nutshell. Church-Turing Thesis Turing Machine equal Notion of an Algorithm Turing Machine

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LR-Grammars

LR-Grammars. LR(0), LR(1), and LR(K). Deterministic Context-Free Languages. DCFL A family of languages that are accepted by a Deterministic Pushdown Automaton (DPDA) Many programming languages can be described by means of DCFLs. Prefix and Proper Prefix. Prefix (of a string)

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Properties of Context-Free languages

Properties of Context-Free languages. Union. Context-free languages are closed under:. Union. is context free. is context free. is context-free. Example. Language. Grammar. Union. In general:. For context-free languages with context-free grammars and start variables .

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CS21 Decidability and Tractability

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Critique this PDA for L= { u u R v v R : u ? {0,1}* and v ? {0,1}+ }

Critique this PDA for L= { u u R v v R : u ? {0,1}* and v ? {0,1}+ }. After you identify the bugs and inefficiencies, design a nicer PDA for this language that is correct. Assignment #4 is posted: Due Wed. July 18. Final exam: Tues. Aug. 7, 9:00 AM in ECS 124.

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ON THE EXPRESSIVE POWER OF SHUFFLE PRODUCT

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David Evans cs.virginia/evans

Lecture 10: Context-Free Languages Contextually. David Evans http://www.cs.virginia.edu/evans. cs302: Theory of Computation University of Virginia Computer Science. Exam 1. In class, next Thursday, Feb 28 Covers:. Problem Sets 1-3 + Comments. Exam 1. Lectures 1-10. Sipser Ch 0-2.

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Properties of Context-Free Languages

Properties of Context-Free Languages. Is a certain language context-free? Is the family of CFLs closed under a certain operation?. Pumping Lemma. Let L be an infinite CFL. Then there exists m ? 0 such that any w ? L with |w| ? m can be decomposed as w = uvxyz where: |vy| ? 1

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CSE 105 Theory of Computation

CSE 105 Theory of Computation. Alexander Tsiatas Spring 2012. Theory of Computation Lecture Slides by Alexander Tsiatas is licensed under a Creative Commons Attribution- NonCommercial - ShareAlike 3.0 Unported License. Based on a work at http://peerinstruction4cs.org.

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Decidable Problems of Regular Languages

Decidable Problems of Regular Languages. Answer:. Take the DFA that accepts and check if is accepted . Membership Question. Question:. Given regular language and string how can we check if ? . DFA. DFA. Question:. Given regular language how can we check

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Removing Ambiguity

Removing Ambiguity. Lecture 16 Naveen Z Quazilbash. Overview. Attendance Review of Ambiguity Removing Ambiguity from GFGs Assignment result. Ambiguity-Review.

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Context-Free Grammars

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CFG => PDA

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Context-Free Languages

Giorgi Japaridze Theory of Computability. Context-Free Languages. Chapter 2. 2.1.a. Giorgi Japaridze Theory of Computability. What is a CFG. A ? B A ? ? B ? 0A1. Terminals: 0,1. Variables: A,B. Productions:. Start variable: A.

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The universal Turing machine

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