2 problems

Let ${\Gamma}$ and $G$ be finite groups. For each $n$, consider the complexified rings $\mathbb C\otimes_{\mathbb Z}\mathcal G_{\Gamma}(n)$ and…

Let $X$ be a quasi-projective surface, and let $X^{[n]}$ denote its Hilbert scheme of $n$ points. A Farahat-Higman-type ring associated to $X$ should govern the cohomology rings…