Useless productions

Thread Starter

zulfi100

Joined Jun 7, 2012
656
Hi,
Kindly consider the following productions. How can I identify a useless production?

S->aS|A|C
A->a
B->aa
C->aCb

Somebody please guide me.

Zulfi.
 

WBahn

Joined Mar 31, 2012
26,398
A production is useless if there is no way for it to ever be used in generating a finite-length string beginning with the start variable.
 
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