One of the questions that keeps me awake (during the day) is the following one:

What did a “computer program” mean to Actor X in 1973?

For example, both Christopher Strachey and Edsger Dijkstra viewed a “computer program” as a mathematical object, albeit of a very different kind [1]. (A decade or more earlier, both men did not associate computer programs with mathematical objects pur sang). But what about large parts of the North American computer industry in 1973? How did actors in this field view a “computer program” in 1973?

A recurring theme in my blog posts is the appropriation of the term “computer program” by Dijkstra and other researchers. The “computer program” concept has acquired at least four different meanings during the course of history. It can refer to:

The topic of `Category Mistakes,' which I have discussed in my four previous blog posts is not limited to digital systems. Engineers in all areas use models and they, too, can potentially fall into the trap of mistaking the model for reality.

Before really discussing category mistakes in computer science in follow-up posts, I will first continue testing my aforementioned categories on the writings of people I admire the most. I shall take a 2014 blog post, written by Michael Hicks in connection with the Heartbleed bug. (His post was written on July 1st, 2014 and I accessed it on September 19th, 2016.)

In 2006 I defended my Ph.D. thesis at KU Leuven. Dr. X from abroad was in my defense committee. He had taken the liberty a few days earlier to share with me some of the "fundamental limitations" he had found with regard to transformational systems, such as the system I had designed, implemented, and documented for my Ph.D. defense. (A comprehensive overview of my system later appeared in Science of Computer Programming [1]). Dr. X had already published his theoretical insights and he wanted me to incorporate his findings into my Ph.D. dissertation.