Proofs of Two Conjectures On the Dimensions of Binary Codes

Abstract

Let $\mathcal{L}$ and $\mathcal{L}_0$ be the binary codes generated by the column $\mathbb{F}_2$-null space of the incidence matrix of external points versus passant lines and internal points versus secant lines with respect to a conic in $PG(2, q)$, respectively. We confirm the conjectures on the dimensions of $\mathcal{L}$ and $\mathcal{L}_0$ using methods from both finite geometry and modular representation theory.