# Crystal basis for quantum groups and Lie algebras

Lie $g$ be a finite dimensional complex simple Lie algebra and $U_q(g)$ the corresponding quantum group, where $q$ is not a root of unity. Every simple finite dimensional $g$-module is of the form $V(\lambda)$, where $\lambda$ is a dominant weight. Every simple finite dimensional $U_q(g)$-module is also of the form $V(\lambda)$, where $\lambda$ is a dominant weight.

My questions are:

(1) Are there some relation between the crystal basis for a $g$-module $V(\lambda)$ and a $U_q(g)$-module $V(\lambda)$?

(2) Are the crystal graphs for a $g$-module $V(\lambda)$ and a $U_q(g)$-module $V(\lambda)$ the same?

Thank you very much.

(1) Yes, the crystal basis for $V(\lambda)$ is the specialization of the $q$-crystal basis at $q=1$. In fact, that's the only way to construct it.