Congruence classes of triangles in $\mathbb{F}_p^2$
  In this short note, we give a lower bound on the number of congruence classes of triangles in a small set of points in $\mathbb{F}_p^2$. More precisely, for $\mathcal{A}\subset \mathbb{F}_p^2$ with $|\mathcal{A}|\le p^{2/3}$, we prove that the number of congruence classes of triangles determined by points in $\mathcal{A}\times \mathcal{A}$ is at least $|\mathcal{A}|^{7/2}$. This note is not intended for journal publication. 
Pham Van Thang, Le Anh Vinh
math.CO