We consider an extension of minimum cost spanning tree (mcst) problems where some agents do not need to be connected to the source, but might reduce the cost of others to do so. Even if the cost usually cannot be computed in polynomial time, we extend the characterization of the Kar solution...

An airline lands in a number of airports in a region. An airport serves a number of airlines. Each airport charges a given amount of emission fees to those airlines using the airport. The total emission fees from all airports in the region must be shared among all airlines. We propose an...