🚀 go-pugleaf

Let me apologize for the term "ripped off", which I regretted
afterwards.  I should simply have repeated my wish to see a definition
of "diffeomorphism", which I presume will depend on the notions of
"differentiable" and "manifold", which I think it only fair to make
part of the definition.

Examples help, and your current example is greatly appreciated.
However an example cannot completely substitute for a definition,
especially if you give no examples of nondiffeomorphic manifolds: how
does one know that the latter even exist using your examples?

>...I would suggest that you take my  3 lectures and this one to
>a specialist at STANFORD  (surely there must be some specialists at
>STANFORD) and asked them to go over my  3 lectures and ESPECIALLY THE 
>PRESENT ARTICLE  and explain them to you.

Well, I should 'fess up here and explain that I was taking the side of
those wondering whether you really could define "diffeomorphism".
Judging from your examples I'd say you certainly have described an
engineer's working understanding of the concept applicable to some
elementary situations.  This may be all that you demand of your
students, in which case they should find your classes appealingly easy
compared to a taskmaster who demands an understanding of every corner
of the concept.
-- 
                                       |
Vaughan Pratt                          |                          ttarP nahguaV
Why do mirrors reverse words&not lettersrettel ton&sdrow esrever srorrim od yhW