The working conference dealt with recent developments in the field of modelling and optimization and with knowledge based decision support systems. This contributed to the realiza- tion of the aims of the working group 7.6 which are: - to promote theoretical research in the field of optimization including mathematical programming and optimal control; -to encourage the development of sophisticated knowledge based systems in which refined optimization models and algorithms are used; - to contribute to the exchange and dissemination of information and collective experience among the inter- ested groups and individuals; - to support the practical ap- plication of such systems in control, engineering, industry, economy etc. A selection of papers is included into this proceedings vo- lume since they reflect the current state of research in areas of interest to the field of (KB)DDS, and/or they are the value for the dissemination and exchange of information related to research topicsof interest, and/or they describe relevant practical experience related to designing, buil- ding, implementing and using (KB)DSS.