EMPTY CONVEX 5-GONS IN PLANAR POINT SETS
Seong-Yoon Ann, En-Sil Kang · Honam Mathematical Journal · 2009
Erd $\"{o}$ s posed the problem of determining the minimum number g(n) such that any set of g(n) points in general position in the plane contains an empty convex n-gon. In 1978, Harborth proved that g(5) = 10. We reprove the result in a geometric approach.