This volume presents the proceedings of the thira German-Italian Symposium on the Applications of Mathematics in Industry and Technology sponsored mainly by the research foundations of Germany and Italy, DFG and CNR. We had not published the proceedings of the second symposium held in Germany, but are now convinced that a publication would be appreciated by many scientists. The aim we had in mind organizing this symposium and communicating its scientific content was essentially the same as in the previous symposia - we were led by the same scientific and cultural (maybe even political) ideas....