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Context free
Grammar
By :
KalpanaNagle
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Points to be discussed
•
• What is grammar.
• Who developed the context free grammar.
• More focused on context free grammar.•
• Relation with artificial intelligent.•
• Importance of context free grammar .
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What is Grammar
•
• Grammar is the study of rules governing the use of language.
• The set of rules governing aparticular language is alsocalled the grammar of the
language; thus, eachlanguage can be said tohave its own distinctgrammar.
•
• Grammar is art of the
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… What is Grammar
Definition : A Grammar G is defined as an orderedquadruple of the form
•
• G = ( V N , V T , S, P )•
• where the entries are identified as follows: V N is anonterminal consisting of the lexical and syntacticcategory labels;
•
•
V T denotes a set of words, called the terminal of G; •
• S is a special member of V N that, in addition to beingthe label of the sentence category, identifies thestarting symbol of G; and
•
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oam Chomskoam Chomsk
oam Chomsky lassified the
rammar into 4.ategories
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Chomsky classification ofGrammar
Type Name Type of Productions
0 Unrestricted
1 Context-Sensitive
2 Context-Free
3 Regular, Finite
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C ntext Free Grammar ntext Free Grammar
A ormal grammar ,is a precisely defined grammar typically used for o mp ut er p ro gr am mi ng
languages .
A en er at ive grammar is a ormal grammar that" " -can in some sense generate the well formed
expressions of a .atural language
An entire branch of in gu ist ic theory is based on.generative grammars e ne ra ti ve g ram ma rs were
popularized by .oam Chomsky
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C ntext Free Grammar ntext Free Grammar
-Context free grammars play a central role in the description and design f r og ra mmi ng la ng ua ge s
and .ompilers
They are also used for analyzing the syntax of.a tural languag es
oam Chomsky has posited that all uman anguages are based on ontext free grammars
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atural language atural languageprocessingrocessing
atural language( )rocessing NLP is the use
of computers to understand uman languages .
enerat ive g ra mma r is the use of rules to onstruct
.entences
oam Chomsky has posited that all uman languages are based on ontext free
grammars
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atural language atural languageprocessingrocessing
( )The goal of Natural Language Processing NLP is to,design and build a computer system that will analyze
, - .understand and generate natural human languages
Applications of NLP include machine translation of- ;one human language text to another
- ,Generation of human language text such as fiction, ;manuals and general descriptions interfacing to other systems such as databases and robotic systems
-Thus enabling the use of human language type commands; -and queries and understanding human language text to
.provide a summary or to draw conclusions
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atural language atural languageprocessingrocessing
One of the easiest tasks for a NLP system is to parse.a sentence to determine its syntax
A more difficult task is determining the semantic.meaning of a sentence One of the most difficult tasks
is the analysis of the context to determine the true.meaning and comparing that with other text
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Computers
r ti fi ci a l Int el ligence Algorithms
Databases
Networking
Robotics
Search
at ural L anguage P roces sing
InformationRetrieval
achineTranslation
anguageAnalysis
Semantics Parsing
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Natural Language Processing
•
• Subfield of Artificial Intelligence (AI) – Typically seen as one part of knowledge
representation•
• Can also be seen as a combination of computer science and linguistics.
– Computational Linguistics•
• Applications – English as a command language – Database queries – Translation systems – Speech recognition systems
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Linguistics
•
• Human language divides into five levels
1.2. Phonology• How sounds are used in language
3.4. Morphology
• Word formation
5.6. Syntax
• Sentence formation7.8. Semantics
•
Sentence meaning9.
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:NY QUERIES
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