Is there any difference between derivation tree and parse tree ?

Question

I have gone through this link and found that both are synonyms to each other but I am not getting that when we have more than one parse tree for a string so do we say that the grammar is ambiguous since in the parse tree we haven't mentioned whether it is a left-most-derivation tree or right-most-derivation tree and we say that for a grammar  to be unambiguous we should have a unique left-most derivation tree and unique right-most derivation tree .

 

http://stackoverflow.com/questions/5729961/any-differences-between-terms-parse-trees-and-derivation-trees

Comments

 if a grammar derives one string with left derivation as well as right derivation then it is ambiguous , if both left and right derivation correspond to 2 different parse trees 

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Sir plz see this question ,here first option is marked false , and as u said that if they have same left-most derivation and right-most derivation then the grammar is unambiguous ,

https://gateoverflow.in/711/gate2001_1-18

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Recheck there is nothing given about corresponding trees. if don't have two different (looking) tree, we can't say it is ambiguous.

Answer 1

Both derivation tree and parse tree are same.

The tree made for each derivation (right most or left most) would be the same. So, for an unambiguous grammar be have a single parse/derivation tree.

Comments

Would like to add one point for an unambiguous grammar u may have more than one parse tree since left-most derivation tree and right-most derivation tree are two different parse trees and for an unambiguous grammar we have a unique left-most derivation tree and unique right-most derivation tree .

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For ambiguous, we will have more than one parse tree. (for sure)

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for any particular string let's say "w":-

number of parse tree = number of LMD  = number of RMD