| Contents | 8 |
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| List of Tables | 14 |
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| List of Figures | 16 |
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| List of Abbreviations | 18 |
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| List of Symbols | 20 |
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| 1 Introduction | 23 |
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| 1.1 Motivation | 24 |
| 1.2 Research Objectives | 25 |
| 1.3 Outline | 26 |
| Part I Foundations of Stochastic Inventory Control | 29 |
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| 2 Basic Concepts of Inventory Management | 30 |
| 2.1 Inventory Management and Control | 31 |
| 2.2 Motivations for Holding Inventory | 32 |
| 2.3 Classification of Inventories | 34 |
| 2.3.1 The Strategic Perspective | 34 |
| 2.3.2 The Operational Perspective | 35 |
| 2.4 Inventory-related Costs | 37 |
| 2.4.1 Order Cost | 37 |
| 2.4.2 Holding Cost | 38 |
| 2.4.3 Penalty Cost | 39 |
| 2.5 Service Level | 40 |
| 3 Stochastic Inventory Control | 42 |
| 3.1 Characteristics of Inventory Models | 43 |
| 3.1.1 Management Decisions | 43 |
| 3.1.2 System-Inherent Characteristics | 44 |
| 3.2 Types of Inventory Control Policies | 46 |
| 3.3 Periodic Inventory Control | 48 |
| 3.3.1 Single-Period Inventory Control | 49 |
| 3.3.2 Multi-Period Inventory Control | 50 |
| 3.3.3 Service-Constraint Multi-Period Inventory Control | 53 |
| Part II Essential Stochastic Processes | 54 |
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| 4 Markov Chains | 55 |
| 4.1 The Markov Property | 56 |
| 4.2 Homogeneous Markov Chains | 57 |
| 4.3 Limit Distribution and Invariant Distribution | 58 |
| 4.4 Communication Classes | 60 |
| 4.5 Class Properties | 61 |
| 4.5.1 Aperiodicity | 61 |
| 4.5.2 Recurrency and Transiency | 61 |
| 4.5.3 Class Criteria | 63 |
| 4.6 Uniqueness of Limit Distributions | 64 |
| 4.7 Multi-Dimensional Markov Chains | 65 |
| 4.8 Applications of Markov Chains | 66 |
| 5 Numerical Solution of Infinite Markov Chains | 67 |
| 5.1 System Reduction Approaches | 68 |
| 5.1.1 Reduced System Approaches | 68 |
| 5.1.2 Geometric Tail Distributions | 69 |
| 5.2 State Space Reduction Approaches | 70 |
| 5.2.1 Augmentations | 70 |
| 5.2.2 Pointwise Convergence | 72 |
| 5.3 Algorithms | 74 |
| 5.3.1 Sheskin’s Partitioning Algorithm | 74 |
| 5.3.2 Power Iteration | 76 |
| 5.4 Criteria for Choosing a Specific Algorithm | 76 |
| 6 Comparing Stochastic Processes | 78 |
| 6.1 Stochastic Ordering for Distribution Functions | 78 |
| 6.2 The Sample Path Method | 80 |
| Part III Stochastic Inventory Control with Customer Segmentation | 82 |
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| 7 Introduction to Inventory Rationing | 83 |
| 7.1 Examples for Different Customer Classes | 84 |
| 7.2 Related Areas | 85 |
| 7.3 Rationing Rules | 87 |
| 7.4 Backorders and Backorder Clearing Mechanisms | 89 |
| 7.5 Literature Review | 91 |
| 7.5.1 Characterizations of the Optimal Policy | 91 |
| 7.5.2 Evaluations and Optimizations of Critical Level Policies | 94 |
| 7.5.3 Other Studies Involving Critical Level Rationing | 98 |
| 7.6 Classification of Our Work | 99 |
| 8 A Markov-Chain Based Modeling Approach | 101 |
| 8.1 Modeling Framework | 102 |
| 8.2 Recursive Expressions for Backorders | 102 |
| 8.3 Markov Chain | 104 |
| 8.4 Structural Results | 105 |
| 8.5 Proofs | 108 |
| 9 Prioritization by Penalty Costs | 115 |
| 9.1 Optimization Approach | 116 |
| 9.1.1 Convexity of Objective Function | 116 |
| 9.1.2 Transition Matrix | 118 |
| 9.1.3 Cost Function | 119 |
| 9.1.4 Numerical Optimization Algorithm | 120 |
| 9.2 Numerical Results | 120 |
| 9.2.1 Critical Level Policy versus Benchmark Policies | 121 |
| 9.2.2 Combination Heuristic | 124 |
| 9.3 Conclusion | 124 |
| 9.4 Proofs | 126 |
| 10 Prioritization by Service Levels | 129 |
| 10.1 Analytical Insights | 130 |
| 10.1.1 Service Level Constraints | 130 |
| 10.1.2 Potentially Optimal Parameter Constellations | 133 |
| 10.1.3 Structural Results for the Optimal Solution | 135 |
| 10.1.4 Cost Function | 137 |
| 10.1.5 Model Alteration: ?-Service Levels | 138 |
| 10.2 Numerical Results | 139 |
| 10.2.1 Optimization Algorithm | 140 |
| 10.2.2 Critical Level Policy versus Benchmark Policies | 141 |
| 10.2.3 Heuristic Approach | 144 |
| 10.3 Conclusion | 145 |
| 10.4 Proofs | 147 |
| 11 Dynamic Rationing Policies | 153 |
| 11.1 The Next Period Optimization Policy | 154 |
| 11.1.1 The Policy | 154 |
| 11.1.2 Structural results | 155 |
| 11.2 The Linear Critical Level Policy | 156 |
| 11.2.1 The Policy | 156 |
| 11.2.2 Structural results | 157 |
| 11.3 Efficiency of the Dynamic Rationing Policies | 160 |
| 11.3.1 Next Period Optimization and Constant Rationing Policy | 161 |
| 11.3.2 Linear Critical Level Policy and Constant Rationing Policy | 165 |
| 11.3.3 Next Period Optimization and Linear Critical Level Policy | 168 |
| 11.4 Conclusion | 170 |
| 11.5 Proofs | 171 |
| 12 Conclusion and Critical Review | 174 |
| 12.1 Contributions | 174 |
| 12.2 Critical Review | 176 |
| 12.3 Future Research | 177 |
| Bibliography | 179 |