Two different kinds of information, i.e. qualitative and quantitative, are currently involved in the implementation of an engineering design. However, qualitative information has always been excluded from the numerical design optimization process, so that the solution obtained was actually suboptimal. A qualitative programming method for the design decision-making problem is described in the
... [Show full abstract] present paper, making use of qualitative information which has been obtained during the conceptual design stage of engineering design. Qualitative information as well as incomplete information could be considered during the design process by applying the qualitative programming method. Two engineering design examples, i.e. structural design and industrial design, are demonstrated to illustrate the application capability of the proposed approach.