Sample Practice

Question

Consider this grammar:
S → SS | a
How many derivation trees are possible for a4?
(a) 3 (b) 4
(c) 5 (d) 6

 

how to generalize for any values if a^5 or a^7 is there any general formulae?

Answer 1

1^st possibility :

Second Possibility : 

Third possibility :

Second and third possibilty are possible for RHS side also so total  = 1+ (2+2) = 5

Comments

thanks but is there any generalized formulae?

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No there is no formula.