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?

[Here are the contents of some visuals from Dijkstra's presentation in Geneva, 1973. Source: my archives, Box 11]

(1A)
Our programs serve to instruct our machines.
-->   A “mismatch” is blamed on the program.

(1B)
Our machines serve to execute our programs.
-->   A “mismatch” is blamed on the machine.

[The following words, written by Dijkstra in January 1973, are from Box 9 in my archive.]

Things I would like to do (they are not all unrelated).

1) write a book on the art of programming.

2) find a good notation for doing justice to representational abstraction.

3) investigate axiomatic definition of semantics with the aim of

To clarify his step-wise program composition, Dijkstra used terms like “program layers” and “levels of abstraction” in his `Notes on Structured Programming' [1, Chapter 1]. These terms were not well defined as Dijkstra conceded later. As a result, Dijkstra's exposition — although extremely rich in content — was difficult to understand completely. See e.g. Denning's clarifying article on Structured Programming [3] or my interview with Liskov who mentions Parnas in this regard [2].

Although he was a theoretical physicist by education, Dijkstra had been exposed to his mother's mathematical thinking during most of his teens. This observation helps explain why he continued to seek general mathematical arguments in his 1972 `Notes on Structured Programming'.