Number of diagonal-quadrangles
Source: Austrian-Polish 2005, Problem 1
July 5, 2015
EnumerationcombinatoricsPolygons
Problem Statement
For a convex -gon , we say that a convex quadrangle is a diagonal-quadrangle of , if its vertices are vertices of and its sides are diagonals of . Let be the number of diagonal-quadrangles of a convex -gon. Determine for all .