a copsychus and a sparrow, move across edges of a regular polygon
Source: Mathley 2014.3 p1
August 18, 2020
combinatorics
Problem Statement
A copsychus and a sparrow, each initially located at one of the vertex of a regular polygon with edges, fly clockwise to another vertex each. The copsychus moves across edges each time while the sparrow moves through edges of the polygon, where are both integers less than . Assume that, during their journeys, the copsychus has stopped at vertices while sparrow has stopped at vertices of the polygon, for . Determine the value of given that there is only one common single vertex of the polygon that both of birds have stopped at, and there is only one vertex that neither of the birds have reached.Vu Thi Khoi, Topo University, Hanoi Mathematics Institute, Vietnam, Hoang Qu6c Vietnam, Hanoi.