BU283 Lecture Notes - Lecture 23: Network Model, 32X, Project A
Document Summary
Network model is one which can be represented by a set of nodes, a set of arcs, and functions (e. g. costs, supplies, demands, etc. ) associated with the arcs and/or nodes. Transportation, assignment, and transshipment problems are all examples of network problems. Shortest route, minimal spanning tree, maximal flow problems: not in syllabus. Project management (pert/cpm: not in syllabus. Can be formulated as lp & solved by computer. If rhs of lp formulations are all integers, optimal solution will be also be integer (special property!) Most s/w contains separate code for these models (to take advantage of their network structure) Network model for a transportation problem with two sources and three destinations follows. Lp formulation: formulated in terms of amounts shipped from origins to destinations, xij, min, constraints. = dj for each destination ji xij > 0 for all i and j: you can see how the number of decision variables and constraints can quickly increase.
