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Conclusions
The representation and characterization of uncertainties in risk assessment is a serious matter, as uncertainties feature strongly in the decision-making process involved in the management of risk. In looking for a general framework for treating uncertainties in risk assessment, we started with the probabilistic treatment of uncertainties, recognizing its merits and limitations, and thus ventured beyond probability to describe uncertainties in a risk assessment context whose setting demands an extension of concepts and methods. This has led us to consider alternative approaches for representing and characterizing uncertainty, including those based on interval probability, possibility theory, and evidence theory. We have made the point, strongly, that extending the framework for uncertainty analysis naturally leads to extending the framework for risk assessment and management. In much of the existing literature on the representation and analysis of uncertainty, risk is defined in relation to probability. For example, using the well-known triplet definition of risk by Kaplan and Garrick (1981) (see also Kaplan, 1997), risk is equal to the triplet (, , ), where is the ...