The Problem of SPM Network Planning Model for Solving the Secondary Shortest Path of Directed Graph

The concepts of shortest path method (SPM) network planning, quasi-float parameters and quasi-critical path are proposed in this paper for the schedule that doesn't have strict predecessor and successor relationship between activities (any activity will be started as long as one of its predecessor activities to be finished), which is based on Dijkstra algorithm and the principle of CPM. The model was established; the nature of the model was analyzed; and the computational formula of quasi-float time was given. Then for the shortest path and secondary shortest path problems of the directed graph, the paper summarized the theorems and corollaries related to path-length of routes, which were analyzed by the theorem and nature of SPM Network planning model. And on this basis, the quasi-feature line method is proposed to solve such problems, and the correctness of the algorithm was analyzed. Finally, it was validated by example.