John Pfaltz, Professor Emeritus

``Discrete systems are dynamic, but how do we describe their change? The calculus doesn't help us here''.

Continuity is seldom mentioned when discussing discrete systems. This is a mistake!

The notion of functional transformations that preserve the structure of the domain is fundamental to all science.

If a function is "continuous", similar inputs should be mapped to similar outputs; why do we not ask if computer procedures are "continuous?''

Office: 222 Reed Hall
Office Phone: (804) 982-2222

US Mail:

Department of Computer Science

Reed Hall
University of Virginia,
Charlottesville, VA 22904, USA

Current Research:

Our current emphasis is on closure systems and their applications to cognitive science. These closure systems provide a formal mechanism for studying the nature of discrete systems which are the ``stuff'' of cognitive science and many other empirical scieces. Moreover, they permit the definition of continuous transformations which are functions on discrete systems. When the discrete systems are concept spaces, discrete continuity models a basic form of learning. The ADAMS database language represents earlier research, but it is no longer an active program. The implemented system is rather unique, and and its suffix based notation has been carried over into our theoretial research. Even though we are not expanding the ADAMS program, it has aspects that are well worth examining. We will provide source code to those interested in implementing this object oriented database system. A comprehensive list of selected publications, including those in the specific areas of research identified above.


After retirement, I sought an interesting project. It was to restore a caboose. The picture at the top shows its condition when delivered by Norfolk Southern from the former Knox and Kane.
The picture below shows its appearance before being its being donated to the Colebrookdale Railroad in Boyertown, PA, where it is currently in regular use.

I also enjoy hiking, camping, and exploring the realm of discrete mathematics.