Multicriterion Decision Aid: Methods and Applications

Traditionally, at least until recently, OR has mainly been based on models which postulate the existence of a unique objective (single-criterion) function. It was thus assumed implicitly that in order to help organizations improve their decision-making, there was a general rule, or objective function, which stood out in everybody’s eyes to indicate the proper direction in which a given system had to be developed (Roy 1988). By doing this, one obtains a mathematical problem which can be defined as a well-formulated problem (i.e. formulated in such terms that the solution, often called the optimal solution, is entirely determined by its formulation). Therefore, it is the formulation of the problem that determines the existence and the content of the solution, usually achieved through algorithms or heuristics.