A Classification of Hyperfocused 12-Arcs

Philip DeOrsey, Stephen G. Hartke, Jason Williford

A $k$-arc in PG($2,q$) is a set of $k$ points no three of which are collinear. A hyperfocused $k$-arc is a $k$-arc in which the $\left(\genfrac{}{}{0ex}{}{k}{2}\right)$ secants meet some external line in exa…