2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/75874Let $S$ be a finite set of points in the plane and let $\mathcal{T}(S)$ be the set of intersection points between pairs of lines passing through any two points in $S$. We characterize all configurations of points $S$ such that iteration of the above operation produces a dense set. We also discuss partial results on the characterization of those finite point-sets with rational coordinates that generate all of $\mathbb Q^2$ through iteration of $\mathcal{T}$.10 pages, 8 figures (low-res for the arXiv), Computational Geometry: Theory and ApplicationsMetric Geometry52C30, 52C10text