2 problems

Let $\mathcal{H}$ be a Hilbert space and let $d\in\mathbb{N}$. Write $\mathcal{C}(\mathcal{H})^{d}_{\operatorname{comm}}$ for the set of $d$-tuples $\{S_i\}_{i=1}^d$ of commuting c…

Nelson's trick conjecture. There should be a Nelson's trick type argument in $2$ variables.