self doubt

Question

what is nullable symbol in CFG???

Comments

A Non-terminal N which explicitly produces null

or produces a null through a series of productions leading to the production of null

Answer 1

suppose we have S->aSb/aAb
                           A->epsilon
now....we can derive epsilon "directly" through A...so A is a nullable variable here;;
we need to eliminate those while eliminating epsilon productions from a CFG;;