MathDB
67 diagonals in regular 134-gon

Source: Portugal OPM 1996 p6

May 18, 2024
combinatoricsgeometrycombinatorial geometry

Problem Statement

In a regular polygon with 134134 sides, 6767 diagonals are drawn so that exactly one diagonal emerges from each vertex. We call the length of a diagonal the number of sides of the polygon included between the vertices of the diagonal and which is less than or equal to 6767. If we order the lengths of the diagonals in ascending order, we obtain a succession of 6767 numbers (d1,d2,...,d67)(d_1,d_2,...,d_{67}). It will be possible to draw diagonals such that
a) (d1,d2,...,d67)=2...26,3...361(d_1,d_2,...,d_{67})=\underbrace{2 ... 2}_{6},\underbrace{3 ... 3}_{61} ?
b) (d1,d2,...,d67)=3...38,6...655.8...84(d_1,d_2,...,d_{67}) =\underbrace{3 ... 3}_{8},\underbrace{6 ... 6}_{55}.\underbrace{8 ... 8}_{4} ?