# Proof of existence of $L\in R\setminus P$

I saw some proof but I didn't understood it, any simple one?

• Do you understand the time hierarchy theorem? – Dmitry Feb 10 at 21:34
• Thanks man! @Dmitry – ChaosPredictor Feb 11 at 6:19

Look at the time hierarchy theorem for an explanation. In particular, we know (using this theorem) that $$P\subsetneq E\subsetneq EXP\subsetneq R$$, and we could have added a lot more complexity classes in between them.