Procedure to remove null production:


To discuss the actual procedure let consider a grammar.



This grammar has null production because λ is not part of the language.


Removal λ – production: 


Step1: To remove λ – production first we generate nullable variable from grammar.


Nullable variable = {B, C, A} Either the same production directly  A  λ or A  λ* indirectly produces λ.


Step 2:

Now we write production from which we do not get λ. Rewrite the production as



So, after rewrite the grammar final grammar G1 is


Then we should add some extra production due to the removal of λ