Is it possible to eliminate the unit rules in this? S -&gt; aA | bC | CC | a | b | C
A -&gt; B
B -&gt; S
C -&gt; A | S


It looks like its going to loop so it would be endless replacing the unit rule....
You can always eliminate unit rules. In fact, every context-free grammar can be massaged to one in Chomsky normal form, and there are several algorithms doing that. Their treatment of unit rules is more subtle than what you suggest.