Elimination of left recursion

1. ELEMINATION OF LEFT RECURSION
Wellcome to our presentation.
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2. Group Members
 MAHMUDULHASAN
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3.  What is left recursion?
 Eliminating left Recursion...
 Example of Eliminating Left Recursion
 Conclusion
 Reference
 Code part
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OVERVIEW

4.  In the formal language theory of computer science , left recursion is a
special case of recursion where a string is recognized as part of a language
by the fact that it decomposes into a string from that same language (on the
left) and a suffix (on the right). For instance 1+2+3 can be recognized as a
sum because it can be broken into 1+2, also a sum, and +3, a suitable
suffix.
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5.  Eliminate left Recursion
 Context Free Grammar
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6. LEFT RECURSION
 The production is left-recursive if the leftmost symbol on the
right side is the same as the non terminal on the left side. For
example,
expr → expr + term.
 If one were to code this production in a recursive-descent
parser, the parser would go in an infinite loop.
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7.  We can eliminate the left-recursion by introducing new nonterminals and
new productions rules.
 For example, the left-recursive grammar is:
E → E + T | T
E → T * F | F
F → (E) | id.
We can redefine E and T without left-recursion as
E → TE`
E`→ + TE` | E
T → FT`
T → * FT` | E
F → (E) | id
Getting rid of such immediate left recursion is not enough. One must get rid of
indirect left recursion too, where two or more nonterminals are mutually left-
recursive
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8. Inquiry
2014-2-60-035@ewu.edu.bd
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9. Referrance
 https://en.wikipedia.org/wiki/Left_recursio
n
http://www.csd.uwo.ca/~moreno/CS447/Lect
ures/Syntax.html/node8.html
www.google.com
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