Stack Exchange network consists of 175 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.
C&\to aC\mid a\\
D&\to aDa\mid bdb\mid\varepsilon
I think that this grammar is infinite so it is not possible to convert it into cnf. Am I correct ?
Every context-free grammar can be converted to Chomsky normal form. Also, note that grammars are by definition finite: a grammar might describe infinitely many strings, but the grammar itself is finite.
Required, but never shown