Research on the Transitivity and Stability of Float

Network planning technology is one of the most important tools for project management, and float is the core content of the technology. In this paper. firstly, theory of float's property is analyzed systemically, which contain properties of total float. free float, safety float and node float; and secondly. transitivity and stability of floats in network planning are discovered, and many new rules and conclusions are found and made based on the above theory. The theory could help to advance the development of project plan and schedule management, and provide theory and method for solving many classical problems, such as the second longest path problem, the time-cost tradeoff problem, the resource leveling problem, etc.