关键词: 网络计划, 网络优化, 时间费用优化, 最小成本加快法

Abstract: In this paper the perfect cut-set of a directed graph is defined as a set which is composed of a forward cut-set and a backward cut-set. The capacity of a perfect cut-set is equal to the capacity difference between the forward cut-set and the backward cut-set. With these definitions the paper presents the theorem with which it is easy to find the time-compressed activities at least cost in a network. The theoremproved by the Graph theory indicates: In the graph composed of the key activities in a network, each forward activity in the cut-set with minimum cost rate is compressed by a unit time and each backward activity in the same cut-set is relaxed by a unit time, the result is the time compression at least cost by a unit time for the whole project, if the compression or the relaxation of the activities in the cut-set is allowed. In the paper the algorithm based on this theorem is discussed in detail.

Key words: network planning, network optimazition, time-cost optimazition, time-compressed method at least cost