Challeng in simplifying the Grammer

[abdullahmogha]

challeng ! in simplifying the grammar

It is a challeng grammar to be simplified by removing all useless, unit, and epsilon (empty string)-productions:

S -> abAB |CD
A -> aBA |epsilon (empty string)
B -> ABb |A |epsilon (empty string)
C -> bb |CD
D -> bD


if no one answer it

 

[hokie1]

D is a useless symbol

The grammar produces all strings beginning with ab and followed any sequence of a and b symbols. An equivalent grammar follows:

S -> ab H
H -> Ha | Hb | epsilon