Software for engineering applications has become, during the last few years, a multi-billion pound industry as applications of computer programs are now an essential part of any engineering project. In spite of this, engineer ing software is not always reliable and many fail to produce good solutions. The extent of this problem, which is very costly to the engineering industry, and its consequences, are somewhat hidden because the software industry has not reached the necessary maturity. An engineer needs a long training before being able to design a body for instance. However, to do that, he...