by Peter Nyikos
I had the honor of delivering a short eulogy for Mary Ellen at this
year’s Spring Topology and Dynamics Conferences (STDC) in Connecticut.
It said: “Mary Ellen was a great mathematician. But she was much more
than that: she was what
Prabir Roy
called a guru — someone you could
turn to for advice and comfort on all kinds of matters… To those of
us who knew her well, she was simply ‘Mary Ellen.’ Whenever
set-theoretic topologists got together for a chat, and someone said
“Mary Ellen,” 99 times out of a hundred, everyone would know who was
being talked about.” I briefly listed some of her main accomplishments, including of course the writing of “Mary Ellen’s booklet”
[1].
another expression that usually gets instant recognition.
Among her research accomplishments is a beautiful generalization of
the Hahn–Mazurkiewicz theorem. It is an immediate corollary of her
solution to Nikiel’s Conjecture
[3]
and of a 1988 theorem of
Nikiel
[e3].
The Hahn–Mazurkiewicz theorem states that, if a metrizable
space is a locally connected continuum (compact, connected space),
then it is a continuous image of
![](https://celebratio.org/media/cunit/None_cunit_keiko_rudin.jpg)
I closed my eulogy by expressing the hope that there would be some
publications in remembrance of Mary Ellen that would do justice to her
greatness, and I am very happy to be able to contribute both to the
special issue of Topology and its Applications dedicated to Mary Ellen
and to this remembrance. I got a unique taste of Mary Ellen’s
graciousness and hospitality in early 1974, when I was a postdoctoral
student at the University of Chicago. She invited me up to Madison,
where I arrived with a bad cold (I naïvely decided not to postpone the
visit, which had already been delayed a number of times), but although
it was obvious to everyone, she never mentioned it once and had me
stay overnight at her house, where I met her two sons and played board
games with them. The same evening she introduced me to the axioms
Her paper on her screenable Dowker space
[2]
solved a 1955 problem
of
Nagami
whether every normal, screenable space is paracompact
[e1].
The proof of normality was a tour de force, amazing in its
originality. I had never seen anything remotely like it, nor the way
she was able to use the intricate set-theoretic axiom
![](https://celebratio.org/media/cunit/None_cunit_retirement.jpg)
There were some problems in set-theoretic topology which Mary Ellen
could not solve but on which she did obtain large “consolation
prizes.” One such prize was her screenable Dowker space, an offshoot
of her unsuccessful attempts to solve a problem for which we still
have no consistency results: is there a normal space with a