'Different parse trees' diaporamas de présentation

Jeff Edmonds York University

2001 Context Free Grammars. ? Op ?. Context Free Grammars Chomsky Hierarchy Ambiguity Java Like Example Human Languages Union, Concat , Spew, & Plop NFA to Context Free Grammar Closure and Proof Big Enough Parsing/Compiling Chomsky Normal Form Context Sensitive Grammars

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Where Syntax Meets Semantics

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CS21 Decidability and Tractability

CS21 Decidability and Tractability. Lecture 5 January 15, 2014. Outline. Pushdown Automata Context-Free Grammars and Languages parse trees ambiguity normal form equivalence of NPDAs and CFGs. NPDA diagram. tape alphabet ? stack alphabet ?.

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Context-Free Grammars

Context-Free Grammars. Using grammars in parsers. Outline. Parsing Process Grammars Context-free grammar Backus-Naur Form (BNF) Parse Tree and Abstract Syntax Tree Ambiguous Grammar Extended Backus-Naur Form (EBNF). Parsing Process. Call the scanner to get tokens

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COP4020 Programming Languages

COP4020 Programming Languages. Syntax analysis Prof. Xin Yuan. Overview. Syntax analysis overview Grammar and context-free grammar Grammar derivations Parse trees. Syntax analysis. Syntax analysis is done by the parser.

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Exercise 1: Balanced Parentheses

Exercise 1: Balanced Parentheses. Show that the following balanced parentheses grammar is ambiguous (by finding two parse trees for some input sequence) and find unambiguous grammar for the same language. B ::= ? | ( B ) | B B. Remark.

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CSCI 2670 Introduction to Theory of Computing

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CSCI 2670 Introduction to Theory of Computing

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Discussion #4 Ambiguity & Precedence Grammars

Discussion #4 Ambiguity & Precedence Grammars. Topics. Ambiguity Precedence Grammars Grammar Reductions. Problems with Grammars. We are heading towards grammars that are reasonable , get the job done , and for which we can find efficient parsing algorithms . Not all grammars are usable!

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About Grammars

About Grammars. CS 130 Theory of Computation HMU Textbook: Sec 7.1, 6.3, 5.4. About grammars. Simplifying grammars Normal forms for grammars Grammar Ambiguity. Grammar Productions. Formal definition of a grammar provides much leeway

378 views • 17 slides