Removing ambiguity-from-cfg
Download as PPTX, PDF2 likes1,164 views
The document discusses ambiguity in context free grammars. It provides two examples of grammars that are ambiguous and shows that there are multiple leftmost derivations for strings generated by these grammars. Specifically, the grammars presented have two different leftmost derivation trees for the strings "aab" and "a+a+a" respectively, showing that the grammars are ambiguous.
Related topics:1 of 9
Download to read offline
Removing ambiguity-from-cfg
- 2. Group Members: 1. Muradul Islam Jamil (152-35-1203) 2. Mahadi Hasan Joy (152-35-1207) 3. Mazed Mourshed (152-35-1215) Md. Anwar Hossen Lecturer, Dept. of Software Engineering Daffodil International University 2
- 3. AMBIGUITY IN CFG If a context free grammar has more than one derivation tree for some string, it is called an ambiguous grammar. There exist multiple right-most or left-most derivations for some string generated from that grammar. 3
- 4. PROBLEM Check whether the grammar G with production rules − S → AB | aaB A → a | Aa B → b 4
- 5. SOLUTION Let’s find out the derivation tree for the string “aab". It has two leftmost deriv i) S → aaB → aab ii) S → AB →AaB → aaB → aab 5
- 6. ANOTHER PROBLEM Check whether the grammar G with production rules − S → S + S | S * S | a 6
- 7. SOLUTION Let’s find out the derivation tree for the string “a+a+a". It has two leftmost d i) S → S + S → S + S + S → a + a + S → a + a + a ii) S → S + S → S + S + S → S + a + a → a + a + a 7
- 8. SOLUTION Let’s find out the derivation tree for the string “a+a*a". It has two leftmost de i) S → S + S → a + S → a + S * S → a + a * a ii) S → S * S → S + S * S → a + a * S → a + a * a 8
- 9. THANK YOU 9