Geeksforgeeks quiz

Question

Let G be the CFG, l be the number of left most derivations, r be the number of right most derivations and P be the number of parse trees. Assume l , r and P are computed for a particular string. For a given CFG ‘G’ and given string ‘w’, what is the relation between l , P , r ?

A	l ≤ P ≥ r
B	l = P = r
C	l ≥ P ≤ r
D	none of these

Comments

B) is the answer

Explanation:- for a unambiguous CFG, No of parse tree p = 1

No of left most derivation l = 1

and no of right most derivation r = 1

Answer 1

for an unambiguous cfg the no. of parse tree==no. of lmd==no. of rmd==1; therefore for that B will be correct

but for ambiguous cfg the no of parse tree >=no. of rmd and alo with the lmd then ans will be A

but in the question it is not given clearly therefore the answer will be B only becoz it is the most expected ans we consider cfg as unambiguous only