Let $\mathfrak{g}$ be a simple finite-dimensional complex Lie algebra and set by $\tilde{\mathfrak{g}}:=\mathfrak{g}\otimes_{\mathbb C} \mathbb{C}[t,t^{-1}]$ its loop algebra.
How to express the universal enveloping algebra $U(\tilde{\mathfrak{g}})$ of $\tilde{\mathfrak{g}}$ as a quotient $\frac{ A_{X}}{I}$, where $A_{X}$ is a free associative algebra over some set $X$ and $I$ is an ideal of $A_{X}$?