I've read in an article that $coRP = RP$ is an open question, but that it is obvious that $coRP \subseteq RP^{RP}$.If $L \in coRP$, I don't understand how access to the oracle helps to build a probabilistic machine that proves $L \in RP^{RP}$.Any explanation would be appreciated.
Prove that $coRP \subseteq RP^{RP}$
complexity theory;complexity classes
Suppose $L \in \mathsf{coRP}$, so that $\overline{L} \in \mathsf{RP}$. Using an oracle to $\mathsf{RP}$ we can determine whether a given string $x$ is in $\overline{L}$, and so whether $x \in L$. This gives a $\mathsf{P}^{\mathsf{RP}}$ algorithm for $L$.