High-speed calculation of the critical paths of large networks

During an investigation of several project network techniques for their applicability to the effective description of business problems, it became evident that more efficient computer programs than those currently available could be written for large networks. Heretofore, critical-path computations have been divided into several phases. The experimental program described here employs a one-phase calculation procedure that eliminates much of the preprocessing of input data required by other methods and therefore achieves faster calculation speed. Written for the IBM 7090, the program calculates the critical path as well as early and late start times for large project networks without requiring the storage of intermediate results on magnetic tape. A formal descriptive language is used to describe the basic algorithm, first at a functional level and then at a machine-dependent level.