6 problems

Let $f=(f^i)_{i=1}^k$ and $g=(g^i)_{i=1}^k$ be the data appearing in Theorems 1 and 2, and let $i,j\in\{1,\ldots,k\}$. A diagonal assumption on $g$ means the corresponding hypothes…

Type D uniqueness conjecture. The number of lowest-degree invariant second-order PDEs is $1$.

Let $(M,\mathcal{I})$ be an involutive exterior differential system. Let $\dot{\Xi}$ and $\Xi_E$ be the characteristic varieties defined in the surrounding discussion, viewed as su…

Let $(M,\mathcal{I})$ be an involutive exterior differential system. Let $E$ and $\dot{A}$ denote the tableaux introduced in the surrounding discussion, and let their characteristi…

Let $(M,\mathcal{I})$ be an analytic involutive exterior differential system, considered over $\mathbb{C}$. Write $\operatorname{elem}(\mathcal{I})$ for its elementary system, and…

Let the EDS be systems for embedded 4-spaces in specialized higher-dimensional flat orthonormal frame bundles, whose Cartan characters and well-posedness have been calculated. Intr…