[OT] On the Expressive Power of Programming Languages

[Paul Backus]

On Sunday, 15 November 2020 at 14:53:04 UTC, Russel Winder wrote:
>
> Except that I see/hear no mathematical definition of the 
> concept of "expresiveness".

The talk defines a relation, "more expressive than", between 
languages. As I'm sure you're aware, a relation between pairs of 
elements of a set is sufficient to define an ordering of that 
set. In this case, I believe it is entirely reasonable to refer 
to the ordering so defined as "expressiveness", even if it is not 
explicitly referred to by that name in the talk itself.

Also, I remind you that you are the one that brought the word 
"expressiveness" into this discussion in the first place. In my 
original post, you will note that I took care to use the term 
"more expressive" to refer to the aforementioned relation.