1. 1 Motivations Deciding is a very complex and difficult task. Some people even argue that our ability to make decisions in complex situations is the main feature that distinguishes us from animals (it is also common to say that laughing is the main difference). Nevertheless, when the task is too complex or the interests at stake are too important, it quite often happens that we do not know or we are not sure what to decide and, in many instances, we resort to a decision support technique: an informal one-we toss a coin, we ask an oracle, we visit an astrologer, we consult an expert, we think-or a formal one. Although informal decision support techniques can be of interest, in this book, we will focus on formal ones. Among the latter, we find some well-known decision support techniques: cost-benefit analysis, multiple criteria decision analysis, decision trees, . . . But there are many other ones, sometimes not presented as decision support techniques, that help making decisions. Let us cite but a few examples. • When the director of a school must decide whether a given student will pass or fail, he usually asks each teacher to assess the merits of the student by means of a grade. The director then sums the grades and compares the result to a threshold. • When a bank must decide whether a given client will obtain a credit or not, a technique, called credit scoring, is often used.

Zusammenfassung
Among the latter, we find some well-known decision support techniques: cost-benefit analysis, multiple criteria decision analysis, decision trees, .

Inhalt
1 Introduction.- 1.1 Motivations.- 1.2 Audience.- 1.3 Structure.- 1.4 Outline.- 1.5 Who are the authors?.- 1.6 Conventions.- 1.7 Acknowledgements.- 2 Choosing on the basis of several opinions.- 2.1 Analysis of some voting systems.- 2.2 Modelling the preferences of a voter.- 2.3 The voting process.- 2.4 Social choice and multiple criteria decision support.- 2.5 Conclusions.- 3 Building and aggregating evaluations.- 3.1 Introduction.- 3.2 Grading students in a given course.- 3.3 Aggregating grades.- 3.4 Conclusions.- 4 Constructing measures.- 4.1 The human development index.- 4.2 Air quality index.- 4.3 The decathlon score.- 4.4 Indicators and multiple criteria decision support.- 4.5 Conclusions.- 5 Assessing competing projects.- 5.1 Introduction.- 5.2 The principles of CBA.- 5.3 Some examples in transportation studies.- 5.4 Conclusions.- 6 Comparing on several attributes.- 6.1 Thierry's choice.- 6.2 The weighted sum.- 6.3 The additive value model.- 6.4 Outranking methods.- 6.5 General conclusion.- 7 Deciding automatically.- 7.1 Introduction.- 7.2 A System with Explicit Decision Rules.- 7.3 A System with Implicit Decision Rules.- 7.4 An hybrid approach for automatic decision-making.- 7.5 Conclusion.- 8 Dealing with uncertainty.- 8.1 Introduction.- 8.2 The context.- 8.3 The model.- 8.4 A didactic example.- 8.5 Conclusions.- 9 Supporting decisions.- 9.1 Preliminaries.- 9.2 The Decision Process.- 9.3 Decision Support.- 9.4 Conclusions.- Appendix A.- Appendix B.- 10 Conclusion.- 10.1 Formal methods are all around us.- 10.2 What have we learned?.- 10.3 What can be expected?.