Foreword by Prof EE Rosinger

Partial Differential Equations, or in short PDE-s, and especially the far more difficult nonlinear ones, are ever since Newton, that is, for more than three centuries, the precise mathematical models of the basic laws of physics, chemistry, and lately, a good deal of biology as well. Consequently, modern technology cannot be conceived without PDE-s. As it happens, it is far more difficult to solve PDE-s than to establish, or write them. Quite often, physicists, for instance, come up with a PDE which formulates yet another fundamental law of nature, and for their effort, they get a Nobel Prize. The far harder task of solving those PDE-s, however, falls upon mathematicians. And due to some strange reasons, mathematicians cannot get Nobel Prizes!

The modern theory of solving PDE-s started in the 1930s, and has ever since then been based on the branch of mathematics called functional analysis. This method has managed to solve many of the simpler linear PDE-s, and even some of the far more difficult nonlinear PDE-s. However, its technical complications are considerable, and for solving further PDE-s these complications grow very fast.

In view of that, in the early 1990's, a radically new, much simpler, and far more effective method was introduced, based on the order completion of spaces of smooth functions defined on Euclidean spaces. Our department has ever since been at the forefront of introducing and then developing this new method based on order completion.

To give a simple argument of the power of that new method, one can mention that vast classes of linear and nonlinear PDE-s can be solved and can be given rather classical solutions, classes of PDE-s which the usual functional analytic method cannot even touch.