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Learn about Operations Research, optimization techniques, LP models, and practical applications in BIS. Discover basic optimization techniques like Integer Programming, Simulation, and Stochastic Programming.
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Graduate Program in Business Information Systems Linear Programming and Applications Aslı Sencer
OPERATIONS RESEARCH • What is Operations Research? • Collection of techniques used to • allocate the scarce resources • in the “best” –OPTIMAL – way! • Best of what? • We need an “objective” to be minimized or maximized! • Profit, Cost, Utility, Delay, Distance, Flow, etc. BIS 517-Aslı Sencer
Some applications • Resource allocation • Production and inventory planning • Capacity Planning • Workers and machine scheduling • Investment planning • Formulating marketing and military strategies BIS 517-Aslı Sencer
Some news about OR: • A Wall Street Journal Article lists the use of LP as one of the greatest technological innovations of the past 1000 years. • 1975 Nobel Prize for economics: T.C. Koopmans and L.V. Kantoprovich for their contributions in the field • 1992 Nobel Prize: Harry Markowitz for his LP based research. BIS 517-Aslı Sencer
Basic Optimization Techniques • Linear Programming • Integer and Goal Programming • Transportation, Assignment Models • Network Models • Nonlinear Programming • Stochastic Programming • Also Simulation BIS 517-Aslı Sencer
LINEAR PROGRAMMING • Most successful of all modern quantitative methods. • Program here is not a computer code! It is a plan that efficiently allocate limited resources to achive a goal. • Involves linear relationships, i.e. relations are in the form of lines, planes! BIS 517-Aslı Sencer
Basic LP Models: Product Mix • Redwood Furniture Co. BIS 517-Aslı Sencer
What is the optimal plan to max. Profit? • Option 1: Allocate all resources to the more profitable item. Total quantity, profit? Any resource left? • Option 2: Is it more profitable to produce less chairs and more tables? Linear Programming BIS 517-Aslı Sencer
Formulating a Linear Problem • Define variables: : number of tables produced in a period : number of chairs produced in a period • Define constraints: • Define Objective Function BIS 517-Aslı Sencer
How is an LP solved? • Graphical Method: Applicable to a maximum of two decision variables. • Simplex Method: Applicable to all LP. Takes long to implement manually. • Use softwares based on simplex and other techniques. BIS 517-Aslı Sencer
Graphical Solution Xc 15 Optimal Solution: Xt=4 tables, Xc=9 Chairs Profit*=$96 Constraint 1 11 (4,9) Constraint 2 Xt 10 22 BIS 517-Aslı Sencer
Basic LP Models: Feed Mix • Two types of seeds are mixed to formulate the wheat of wild birdseed. BIS 517-Aslı Sencer
LP Formulation BIS 517-Aslı Sencer
Graphical Solution to Feed Mix Problem Xs Optimal Solution: Xb*=3750 lb, Xs*=7500 lb Cost*=$1425 (3750,7500) (15000,0) (10000,0) Xb Roughage Fat Protein BIS 517-Aslı Sencer
Types of Feasible Regions Bounded Feasible Region Unbounded Feasible Region BIS 517-Aslı Sencer
Cases in an LP: Infeasible Solution Do all LP has an optimal Solution? No feasible region If an LP has no feasible region, then the solution is INFEASIBLE! BIS 517-Aslı Sencer
Cases in an LP: Multiple Optima Optimal Solutions: Point(1): X1*=4 2/7, X2*=6 3/7 Point(2): X1*=6 6/7, X2*=4 2/7 P*=$120 Infinite number of optimal solutions exist in the form (1) (2) BIS 517-Aslı Sencer
Cases in an LP: Unbounded Optimal Solution Optimal Solution: X1*=, X2*= P*= BIS 517-Aslı Sencer
Solving Linear Programs with a Spreadsheet • Write out the formulation table • Put the formulation table into a spreadsheet • Use Excel’s Solver to obtain a solution BIS 517-Aslı Sencer
Solution in the Excel Solver BIS 517-Aslı Sencer
Applications of LP:Transportation Models • Sporting goods company Warehouses Demand Capacity Plants Frankfurt 100 300 200 Juarez 150 100 200 150 NY Seoul Phoenx Tel Aviv Yokohama BIS 517-Aslı Sencer
LP:Transportation Models (cont’d.) • What are the optimal shipping quantities from the • plants to the warehouses, if the demand has to be met • by limited capacities while the shipping cost is minimized? Shipping Costs per pair of skis BIS 517-Aslı Sencer
LP:Transportation Models (cont’d.) Xij: Number of units shipped from plant i to warehouse j. i=1,2,3 and j=1,2,3,4. Minimize shipping costs=19X11+7X12+3X13+21X14 +15X21+21X22+18X23+6X24 +11X31+14X32+15X33+22X34 BIS 517-Aslı Sencer
LP:Transportation Models (cont’d.) subject to #shipped from a plant can not exceed the capacity: X11+X12+X13+X14≤100 (Juarez Plant) X21+X22+X23+X24≤300 (Seoul Plant) X31+X32+X33+X34≤200 (Tel Aviv Plant) #shipped to a warehouse can not be less than the demand: X11+X21+X31≥150 (Frankfurt) X12+X22+X32≥100 (NY) X13+X23+X33≥200 (Phoenix) X14+X24+X34≥150 (Yokohama) Nonnegativity Xij ≥0 for all i,j. BIS 517-Aslı Sencer
LP:Transportation Models (cont’d.) Optimal Solution: Optimal cost=$6,250 Warehouses Demand Capacity Plants Frankfurt 100 300 200 Juarez 150 100 200 150 50 100 NY Seoul 100 100 Phoenx Tel Aviv 100 Yokohama 150 BIS 517-Aslı Sencer
LP: Marketing Applications • How to allocate advertising budget between mediums such as TV, radio, billboard or magazines? Ex: Real Reels Co. Allocated ad. Budget=$100,000 • No more than 5 ads in True and at least two ads in Playboy and Esquire BIS 517-Aslı Sencer
LP: Marketing Applications (cont’d.) Not integer? BIS 517-Aslı Sencer
LP: Assignment Models • Assignment of a set of workers to a set of jobs BIS 517-Aslı Sencer
LP: Assignment Models (cont’d.) BIS 517-Aslı Sencer
LP: Diet Problem • How much to use of each ingredient so that the nutritional requirements are met in the cheapest way? • Ex: Feed Mix problem given at the beginning of the lecture BIS 517-Aslı Sencer
LP:Labor Planning • Addresses staffing needs over a specific time period. Hong Kong Bank of Commerce: • 12 Full time workers available, but may fire some. • Use part time workers who has to work for 4 consequtive hours in a day. • Luch time is one hour between 11a.m. and 1p.m. shared by full time workers. • Total part time hours is less than 50% of the day’s total requirement. • Part-timers earn $4/hr (=$16/day) and full timers earn $50/day. BIS 517-Aslı Sencer
LP:Labor Planning (Cont’d.) BIS 517-Aslı Sencer
LP:Labor Planning (cont’d.) BIS 517-Aslı Sencer