Given a field $k$ of characteristic zero, let $R = k_{-1}[x_1, ..., x_n]$ denote the $(-1)$ skew-polynomial ring; i.e., the ring generated from $n$ indeterminates $\{x_i\}_{i=1}^n$ over $k$ such that $x_i x_j = - x_j x_i$ ...