5 problems

For $\theta\in[0,\pi/2]$, define $C_1$, $C_2$, and $\beta$ by … … where … Let $C_3,C_4,C_5,C_6$ be the matrices defined earlier in equation (CiEquations). Alternative six-matrix fe…

Four-variable matrix-cube optimum conjecture. The optimal value is $\sqrt{13}/2$. This is equivalent to the conjectured optimality of the four-dichotomic-qubit compatibility bound;…

Let $\mathcal D_{A(k)}$ and $\mathcal D_{A(k)}^\square$ be the free spectrahedron and its matrix polar associated with the simplex-plus-line model defined earlier in the paper, and…

Let $k\in\mathbb N$ and $d\geq 2$. The minimum compatibility degree $s_{\mathbb C}(d,2,(2,k+1))$ concerns one dichotomic measurement and one measurement with $k+1$ outcomes on a…

Convexotonic-map conjecture. Up to conjugation by affine linear maps, the only bounded free spectrahedra $cD_A$ and $cD_B$ that are $p$-bianalytic arise as spectrahedral pairs asso…