
The graph in the circle in the illustration is a
twodimensional projection on the plane of a dodecahedron (a
threedimensional solid with twelve pentagonal faces). Each green
point on the graph represents the respective vertex of the
dodecahedron, and each white line between any two points  the
respective edge. Such graphs, which project some threedimensional
problems and puzzles onto the twodimensional plane, are called
Schlegel diagrams.
The object of this puzzle is to visit all the 20 green points on the
graph. You can start at any point but you may visit each point only
once. Moving from point to point you have to travel along the white
lines (alleys) only. You have to finish at the point where you've
started your journey from. 
