Remove unproductive symbols for the following grammar:
P={S- aAb|aAB
A-aA|a
C-bD|CA
B-b|CA|Db
}

Question

Remove unproductive symbols for the following grammar: 
 P={S-> aAb|aAB 
       A->aA|a 
      C->bD|CA 
      B->b|CA|Db 
 }

Accepted Answer

Result:  
 P'={S-> aAb|aAB 
       A->aA|a 
       B->b 
 }

Answer

Result:  
 P'={S-> aAb|aAB 
       A->aA|a 
      C->bD|CA 
      B->b|CA 
 }

Answer

Result:  
 P'={S-> aAb|aAB 
       A->aA|a 
      B->b|Db 
 }

Answer

Result:  
 P={S-> aAb|aAB 
       A->aA|a 
      C->|CA 
      B->b|CA| 
 }

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