3 problems

Geometric griddability and finite-letter-graph conjecture. $X$ is geometrically griddable if and only if ${\cal G}_X$ is a class of $k$-letter graphs for some finite value of $k$.

Let $A$ be a centrosymmetric matrix whose entries belong to $\{0,1,-1\}$, and let $\operatorname{Geom}(A)$ be the associated geometric grid class. An even-size centrosymmetric perm…

Let $M$ be a $0$-$1$ matrix, let $G(M)$ be its associated row-column graph, and let $M_{+\negsub}$ be obtained by negating a single entry of $M$. Assume that $G(M)$ is connected, a…