3 problems

Let $M$ be an $n$-dimensional manifold and let $K_1,\dots,K_n$ be mutual symmetries on $M$ that are linearly independent at every point. For operator fields $L,M$, define the…

Consider an $n$-component quasilinear evolutionary system … where $u=(u^1(x,t),\dots,u^n(x,t))^\top$ is an unknown vector function and $L=L(u)$ is an $n\times n$ matrix viewed as a…

Let $K_1,\dots,K_n$ be $n$-dimensional operator fields that are mutual symmetries, meaning that they satisfy the mutual-symmetry condition, and are linearly independent at every po…