Directed minimum cost spanning tree problems of a special kind are studied, namely those which show up in considering the problem of connecting units (houses) in mountains with a purifier. For such problems an easy method is described to obtain a minimum cost spanning tree. The related cost...

A Chinese postman (CP) game is induced by a a weighted undirected, connected graph in which the edges are identified as players and a vertex is chosen as post-office location. Granot and Granot (2012) characterized graphs that give rise to CP games that are balanced. This note completes this...