On the Optimality of Forest-Type File Transfers on a File Transmission Net

摘要

A problem of obtaining an optimal file transfer on a filetransmission net N is to consider how to transmit, with a minimumtotal cost, copies of a certain file of information from somevertices to others on N by the respective vertices' copy de- mandnumbers. This problem is NP-hard for a general file trans- missionnet. So far, some class of N on which polynomial time algorithms forobtaining an optimal file transfer are designed has been known.