problem solving by using quantitative models and computers
Post on 21-Dec-2015
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Problem Solving by using Quantitative Models and
Computers
?A real-world problem
Understand Problem thoroughly
Select an appropriate model
Formulate the problem into the model
Input into computer in a way that computer can understand
Scrutinize and interpret the computer result
Solve
Result
1 2 3
456
78
Sensitivity Analysis
9
Understanding Problem
• Step 2, understanding problem thoroughly:– Objective,– Conditions and restrictions,– Data needed,– What the result is like.
Formulate Problem
• Step 4, Formulate the problem into the selected model– Re-describe the problem in terms of the
model• In LP, objective function and constraints• In transportation model, sources and destinations.
Input into Computer
• Step 5, Input the problem into computer in a way that computer understands– Select software package for solving the model
(QM or Excel, for example)– Input the data into the proper model following
the data format.
Work with Results
• Step 8, Scrutinize and interpret the result from computer– Understand the output of computer.– Observe the result to see whether it is
reasonable, whether it makes sense.– Interpret the result from managerial point of
view.
Sensitivity Analysis
• Sensitivity analysis is to see how possible changes of parameters in the model would impact on the optimal solution.
Additional Restrictions
• Additional restrictions can be dealt with before or after the computer solves the problem.– Before. Re-formulate the model to
incorporate the additional restrictions.– After. Modify the computer result to reflect the
additional restrictions.
Manipulations
• The real-world problem usually does not fit a model perfectly, where manipulations are needed.– Manipulation is handling some conditions or
parameters in indirect but equivalent ways.– Examples:
• Prohibited route in the transportation model• Solving assignment problem by using
transportation model
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