Forbidden Families of Minimal Quadratic and Cubic Configurations

Abstract

A matrix is \emph{simple} if it is a (0,1)-matrix and there are no repeated columns. Given a (0,1)-matrix $F$, we say a matrix $A$ has $F$ as a \emph{configuration}, denoted $F\prec A$, if there is a submatrix of $A$ which is a row and column permutation of $F$. Let $|A|$ denote the number of columns of $A$. Let $\mathcal{F}$ be a family of matrices. We define the extremal function $\text{forb}(m,\mathcal{F})=\max \{|A|:A\text{ is an }m-\text{rowed simple matrix and has no configuration }F\in \mathcal{F}\}$. We consider pairs $\mathcal{F}=\{F_1,F_2\}$ such that $F_1$ and $F_2$ have no common extremal construction and derive that individually each $\text{forb}(m,F_i)$ has greater asymptotic growth than $\text{forb}(m,\mathcal{F})$, extending research started by Anstee and Koch.

References in corpus (1)

• Unavoidable Multicoloured Families of Configurations