I should definitely have asked more precisely:
** Which generally available English language textbook defines
** T0-spaces and calls them Kolmogorov?
** ----------
** (Kelley and Dugundji do not mention Kolmogorov.
** ----------
That's why the T_0 exercise in Kelley wouldn't do ...
Thanks for the pointers to it! Sorry that I took your time.
For reasons of mere curiosity, it would be even greater also to know
why on earth "Kolmogorov"! Of course, he was/is famous, but
I guess his name was not chosen accidentally.
Did he define them first, or some precursor version of them?
Regards,
Bernd
PS:
In case you want to know why I don't just use "T_0" in my paper:
I found T_0 very important in a generalization of topology,
and I want to extend T_0 to that generalization. However,
my paper is intended for an audience most of whom do not care
about topology. So I want to avoid "T_0", because it would, all
alone, look somewhat unmotivated to non-topologists.
(Why T_0? What about T_(some other number)?")
Kuratowski ("Topology", vol. I, p. 51) attributes T_0 to
Kolmogorov, and gives as reference Alexandroff-Hopf.
Ilias