General model and choice criterion in engineering design

A universal model of a structure of an elementary design task solving (the horizontal structure) is presented, emphasizing the activities concerning a choice: appraisal, selection, optimazation and decision. Requirements for the value system are defined and some transformation sequence of a choice criterion from the primary criterion (not strictly defined) to the task criterion (accurately defined, measurable) is proposed. A method is given of determining this criterion for random, fuzzy or deterministic requirements, imposed on a design, design variables and performance variables, using the utility function and weighting factors.