Male and Liebman [40] propose a districting heuristic based on
the construction of an auxiliary graph, called cyclenode graph, in
which nodes represent trips and edges represent feasible trips
aggregations. The approach is based on the partition of an Eulerian
graph into cycles using a “checkerboard pattern”. This partition is
characterized by a large number of small cycles where every edge
of the graph belongs to exactly one of them. Such cycles are then
used to determine the districts.