(apologies, in advance, if this post is a duplicate)
W. E. Perry wrote:
>
> ...
> Paul Prescod dealt with this accurately and conclusively in his 20 Apr post:
> ...
> I've found a good reference to the 8 year old paper that made the
> distinction between inheritance and subtyping most explicit. The paper
> itself is not online, but this summary is quite good:
...
> http://progwww.vub.ac.be/prog/persons/kimmens/research/Introduction-to-OO.html
>
> The paper itself is called: "Inheritance is not subtyping" and is quite
> famous, but unfortunately predates the Web.
>