By accident -- I don't even remember what I was originally searching for -- I just learned that user David Charles Ullrich (2642 answers in Mathematics Stack Exchange; Mathematics Genealogy Project entry; reviews of his publications at Zbl; 1981 Ph.D. under Walter Rudin) died just over 2 weeks ago in Stillwater, Oklahoma on Friday, 22 March 2024. He was born on 15 January 1954. Ullrich was a long-time participant of the Usenet group sci.math (and well-known for his lengthy engagements with some of the trolls and cranks there), which is where nearly all of my interactions with him took place (all positive or neutral that I can recall), this being during 1999-2011.

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    $\begingroup$ A notice on the profile page may be appropriate: math.meta.stackexchange.com/q/35131/42969 $\endgroup$
    – Martin R
    Apr 7 at 19:22
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    $\begingroup$ @Martin R: It appears this is something Xander Henderson will have to do, if it is deemed appropriate in this case. $\endgroup$ Apr 7 at 19:36
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    $\begingroup$ Per the Q&A answered above, questions of memorializing users on Math SE will generally be taken on a case-by-case basis, and will only happen if the community feels that it is appropriate. In this case, I suspect that the community is likely to concur that memorialization is appropriate. I will poke the rest of the moderation team, and see how they feel. In the meantime, everyone please remember that voting on meta indicates "I agree". $\endgroup$
    – Xander Henderson Mod
    Apr 7 at 20:27
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    $\begingroup$ As a long-time poster on sci.math myself, I appreciated Ullrich's contributions, and was pleased to see him here when I came over to mathstack. $\endgroup$ Apr 7 at 22:04
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    $\begingroup$ I lurked on sci.math (I was much more active on sci.astro.amateur and rec.puzzles) and remember him from there. Sad to hear. $\endgroup$
    – Brian Tung
    Apr 8 at 3:56
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    $\begingroup$ Sadly, we also lost Robin Chapman a few years ago - see here. He was among the most prolific and knowledgeable contributors to sci.math in number theory and algebra, and he would surely have been on the front page here if he had not quit in early days (over a dispute with an SE founder). This site would have been much richer had he stayed. Perhaps his account should also be noted.. $\endgroup$ Apr 8 at 4:35
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    $\begingroup$ Sad news, indeed (about Ullrich as well as Chapman). I recall begin delighted when D.C. Ullrich joined math.SE. (and seeing that R. Chapman was already here when I joined). For the same reasons as others - long common history in sci.math. FWIW, I second the move to memorialize their profile pages $\endgroup$ Apr 8 at 8:12
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    $\begingroup$ I believe when a mathematician passes away, they enter the World of Abstracts, the World of Perfect Beauties, as they were dreaming in this world. I believe they find answers to whatever question they had. My deepest condolences (broken_heart_emoji). $\endgroup$ Apr 8 at 13:31
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    $\begingroup$ This is sad news. He was one of the stalwarts of sci.math. $\endgroup$ Apr 8 at 15:08
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    $\begingroup$ @MostafaAyaz Reminds me of the Endless Space 2 Riftborn. $\endgroup$
    – Red Banana
    Apr 9 at 3:17
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    $\begingroup$ His mind was so consistently sharp I thought he was a hotshot postdoc. "Nothing about me is of any interest whatever", to the contrary. RIP David C. Ullrich $\endgroup$ Apr 9 at 9:17
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    $\begingroup$ His final answer was related to his book Complex Analysis. It also said "I've been locked out, hadn't been checking every day, didn't realize I was back. yippee..." Did a moderator suspend him? $\endgroup$
    – Henry
    Apr 10 at 0:46
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    $\begingroup$ Oh no, this is so sad. I learned a lot from him on Math.SE. This Q&A has been one of the most important learning opportunities of my late PhD. He was a great harmonic analyst and I will miss him dearly. $\endgroup$ Apr 10 at 8:29
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    $\begingroup$ Sad to hear. Had a sense of humour, one response to a comment of mine: Are you sure about that reference? I don't recall anything in Rudin about preventing aliens from reading brain waves. $\endgroup$
    – copper.hat
    Apr 12 at 3:25
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    $\begingroup$ Dang wow. RIP. He helped cultivate a culture of excellence on MSE. May his nearly limitless contributions continue to help future students and budding mathematicians. $\endgroup$ Apr 16 at 17:28

1 Answer 1


I have updated the profile.

I don't have nearly the same connection that several of you from sci.math and the early days of Math SE had to Dr Ullrich, but I have valued his contributions in the time that I have been here.


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