John Horton Conway

John Horton Conway, the John von Neumann Professor in Applied and Computational Mathematics, Emeritus, and professor of mathematics, emeritus, died on April 11

24 thoughts on “John Horton Conway

  1. David Corwin

    I knew him first at Mathcamp when I was in high school, then used to hang out with him in my first two years at Princeton (2009-2011). Here are some memories:

    1) In 2007, he gave a knot theory demonstration at Mathcamp. The most memorable part was when he ripped apart a plastic bag with his teeth to help teach us knot theory (see this photo https://www.facebook.com/dcorwin1/posts/4358648244354)

    2) One day at Mathcamp I came to him and told him that I had just learned about the Mordell-Weil Theorem. His immediate reaction was to recall a fun story of a time he spent at Mordell’s house in Cambridge, mentioning especially the wonderful cake(?) that Mordell’s wife made.

    3) For my first couple of years at Princeton, he would sit in the common room all day and talk math to anyone who would listen. I took advantage of that now and then, and it was always fun to see him there. I was a bit sad when, in later years, he moved out to one of the coves in the hallway with blackboards (maybe they told him not to spend all day in the common room?), but he was still there telling people about math.

    4) There was a funny old phone sitting in the common room (maybe even rotary dial?) that nobody knew what it was doing there. The one time I remember it ringing, it was for Conway.

    5) Conway’s office was what some would call a mess, but what I found quite delightful. I remember in particular a poster he kept in front that had “Conway” in big letters and some sort of price (I guess it was an ad). He always kept his office unlocked, so once or twice I went in just to look (though one time my friend discouraged me from it). I don’t think I ever saw him there.

    6) In the spring of my sophomore year, he taught a graduate seminar on finite simple groups. I have a few memories of the actual math (various stuff about card shuffling and the Mathieu groups), but my biggest memory was of how we figured out when it would be. It was originally scheduled for a certain time with the registrar, but that didn’t work for everybody. Conway told us he was happy to lecture whenever we wanted (‘even at 3am!’ he said). So I made a whenisgood (I still have the link in my email), and we initially decided on Wednesdays at 7:30-9 and on Fridays at 3:30-5. I told everyone in the class but not the registrar, who got upset that we had changed the time without telling them. For some reason, two weeks later the time changed to 9:30-11 on TuTh.

    In characteristic fashion, he would regularly forget to come. So he gave us his cell phone number (I guess that was after he stopped using the rotary phone in the common room), so that we could call him if he didn’t show up to class and couldn’t be found in his usual hangout spots.

    7) In addition to his doomsday algorithm, he devised an algorithm for converting between Hebrew and Gregorian dates, which took only about 1.5 times as long as finding the day of the week (in his head). When he explained it to me, he displayed a surprisingly deep knowledge of the halakha (Jewish religious law) behind how the Hebrew calendar works (mentioning various religious constraints on the Hebrew calendar, including that Passover must be in the Spring, which days of the week certain holidays can’t fall on, etc). (Maybe he was even able to quote a specific rabbinic dispute or opinion? I don’t fully remember.) I don’t remember the algorithm, but I remember there were three important numerical constants one has to memorize to do the algorithm, and he called them “he”, “she”, and “it”. The year after I graduated, he gave a talk at the CJL about his thoughts on the Hebrew calendar.

    8) I’ll never forget this piece of advice he once gave me: “If everybody else is running north, then run south AS FAST AS YOU CAN.”

    He may have meant it primarily as advice about doing mathematics, but I wonder if he would extend it to life as a whole. I recognize there are many situations where that advice doesn’t make sense (literally, at least), but it gives an interesting point of view on life.

  2. Jonathan Strassfeld

    John Conway taught the first class I attended at Princeton. It remains one of my life’s most profound educational experiences. I still remember that day in 2005 when I was among about 40 anxious freshman who showed up to Fine Hall, sat down, and waited… until about 5 minutes after class was supposed to have started. Finally, as we questioned this seemingly inauspicious start to our collegiate education, a gregarious Brit wearing a T-Shirt burst into the room and began to address the class without explanation or ceremony. This set the tone for the semester. MAT 215 had no syllabus. We were only ever assigned two problem sets for homework. Conway would arrive in clothes that looked at least a decade old and abruptly begin to lecture: and by lecture, I mean he just started talking about something that interested him. Of course, his fancies were not the fare of a normal freshman analysis course. For instance, to introduce us to topology, he spent the class discussing Alexander’s horned spheres. We sat there, hanging onto his words for dear life, searching for a scrap of understanding as he took off into the mathematical stratosphere. His motto was “be crude elegantly” – find a boundary, an approximation, or a trick that dispelled superficial complexity. When we finally reached out last class, Conway broke from his usual pattern to provide a list of topics that would be covered on the final exam. As he listed them, they seemed basic – things we had to learn to have any hope of understanding his lectures. We had mastered the subject without realizing it.

    Ave atque vale, Professor Conway. You will always be the image of genius in my mind.

  3. Mathew Ishaq

    Professor Conway was one of my personal mathematical heros and inspirations. I am tremendously heartbroken from these developments. I have no doubt he will continue to teach and inspire future mathematicians through his brilliant work. Rest peacefully, Professor.

  4. Tim Hsu

    Reposted and slightly edited from twitter:

    As a Conway student, I owe him too much to fit in a blog post. So I’ll just mention three things Conway taught me about teaching, plus one (not-so) secret of his.

    1. When I was giving one of my first talks, I asked him for advice, and he told he to prepare what I was going to say, and then cut it in half. Then do it again, and again. Each time it gets better.
    “But when do you stop?”
    “Never. At my advanced age, I can talk forever about nothing, and it’s absolutely WONDERFUL.” (And as many have said over the last few days, it was.)

    2. After I bombed teaching some early class, he told me always to keep in mind that (paraphrasing here) students have more important fish to fry than whatever happened in my class. At the time, he was giving me a way to let that bad class go. But right now, these days, that idea reads differently, and is probably more important than ever.

    3. Towards the end of my graduate career, he told me (I don’t recall the context) that math is such a forbidding subject, it helps to make yourself slightly ridiculous. “Although,” he continued, “that seems to come naturally to you.” I’ve tried my best to live up to that!

    And the (not-so) secret: As you may have seen elsewhere, Conway had the reputation of giving lectures by walking into a room, kicking off his Birkenstocks, and just talking off the top of his head. Nothing could be farther from the truth! (OK, the Birkenstocks part is true.)

    Any particular idea he talked about in public had been gone over infinitely many times, with anyone he could flag down in the hallway, first in embryonic form, then developed and refined ad infinitum (until the listener had to do go do something else). He was preparing his lectures ALL THE TIME, because his whole life was preparation, because his whole life was mathematics.

    So I think it’s not a coincidence that so many of his students love teaching and communicating mathematics – how could we not? Thank you, Prof. Conway, for that and so much else.

  5. Edward Martin

    For one term in 1969-70, the final year of my undergraduate studies at Cambridge, I was fortunate enough to have a weekly one-on-one tutorial session with John Conway in his office at the Department of Pure Maths and Mathematical Statistics, then on Silver Street. What an experience that was! On the back of his office door he had passport-size photos of all the students for whom he was responsible, but in the middle of the array, in alphabetical order, was a photo of his wife, with her name underneath. Rumour had it that he had banned the cleaning staff from ever entering his office. Reportedly, this was because of his practice of working with pen and paper and balling up the paper and tossing it over his shoulder if he didn’t think he was getting anywhere. Then, days later, his current investigation would remind him that he had been thinking about that some time before and he would go digging through the balled-up pieces of paper on the floor to resurrect his earlier efforts.

    At the start of one session he was visibly excited, so I asked what was going on. He said that the previous evening, while he was taking his bath, John Thompson had phoned from Chicago to inform him about the discovery of some mammoth simple group. Conway, dripping wet and clad only in a towel, had then proceeded to work through the night analysing the structure and subgroups of this new discovery.

    On one occasion he was enthusiastically explaining something (I forget what) that was well above my head. He registered my confusion and said helpfully, “Well, you can think of it in terms of sphere-packing in 23 dimensions” — as if that made things any more comprehensible to me!

    The following year I attended a Part III course on Classical Groups given by Conway. On the first day, the lecture had apparently begun a few sentences before he strode into the lecture theatre at race-walking pace with his gown flowing out behind and followed by three or four graduate students, one of whom was carrying a pre-heated 30-cup coffee urn.

    To say that John Conway was a memorable character is a massive understatement. What a legacy he leaves behind him! I shall miss him greatly.

  6. Edip Yuksel

    “John was the most fascinating human being I’ve ever met. He was not only interested in math, he was interested in everything… There were always strange characters showing up at our house, joining us for dinner, or sitting with John out in the back garden” John Conway’s wife Diana Conway.

    This video supports Diana Conway’s statement above.

    https://youtu.be/u3hPpYbjYCs

    During my visit to Princeton University to speak at a Symposium on Constitution, I visited Math Department and met Prof John Conway and Prof Elliott Lieb. It was September 27, 2013.

    I started with a random “random” question, and then presented the code 19 of the Quran to both of them in about half an hour, until their time for the next class.

    After my younger son Matine graduated from Princeton, I met John Conway, again. It was August 14, 2017.

    Of course, we were both 4 years older. Since his office at Math Department was being painted and refurnished, I met him at a small room at Green Hall. We talked for about 2 hours, mostly on math and philosophy. We ate together Turkish delights, drank together Ayran…

    We soon felt like we were old friends. At one moment, we even screamed at each other (un)fortunately, camcorder was dead and those deliciously heated moments were not recorded.
    John was brilliant, curious, humble and friendly. From this video, you may not learn much about math, but you may enjoy the small talk of two very different and curious men.

    After recording this second meeting, we continued communication for some time; but then our communication was disrupted. I hope patience for his family and friends.

  7. Paul Callahan

    While I’m aware that John Conway’s influence and accomplishments go beyond the Game of Life, I have always been more of a computational tinkerer than mathematician, and his simple universal system has inspired me for decades, not only with puzzles, but with an intuitive understanding of what is and is not tractable in computation.

    One of the things that makes a cellular automaton like Life such fertile ground is that while it ultimately presents undecidable problems like any other Turing-equivalent computer, it embeds within it dynamic systems that are tractable, e.g. spaceships, oscillators, puffers, logic gates, etc. So beyond just setting up a pattern and watching it in wonder, there are always components that catch the eye and lead to new questions and analytical techniques. Its study over the past five decades has been something like a recapitulation of physics and chemistry in an artificial universe.

    Conway’s interest in the playful elements of classical mathematics (models, toys, mental exercises like doomsday) is another inspiration that I would like to see pursued in a new generation of mathematicians. Mathematics pursued only on paper is (for some like myself) too austere, yet when tied to high technology runs the risk of hiding what is really going on. Conway was one of those rare people who brought joy by coupling deep and rigorous abstraction with the mind at play.

  8. Tom Baranski

    I first met Professor Conway (“Don’t call me ‘professor’ he would later scold me) at a math lecture he gave at Rutgers in New Brunswick as the “bonus” speaker of an introductory presentation of the then new “Texas Instruments Graphing Calculator” in around 1995 when I was a math instructor at Middlesex County College.

    In his usual casual get-up of T-shirt and sandals, he entertainingly regaled us on the properties of tangents and circles. Almost twenty years later I spied this familiar face (JHC) sitting outside of Panera’s coffee shop on Nassau St. in Princeton, but not remembering his name I tried, “Professor Wiles?” He gruffly corrected me, “Conway,” and I apologized telling him I remembered his face but not name.

    I then asked him if he wouldn’t mind talking to me about Bertrand Russell for just a few minutes….two plus hours later he had given me an in depth lesson on the great old philosopher with asides on Godel and Aristotelian logic as well…me questioning, JHC holding forth brilliantly on what those heavy- hitters meant to mathematics.
    Continuing for years after I was privileged to have JHC as a virtual private tutor on Sunday mornings at Panera’s on everything from the best breakfast treats at Panera’s to “determinism,” the meaning of “randomness,” and how atomic particles have “free will.” JCH was a polymath all right, but with the tone and sparkle of a stand-up comedian and the astonishing insight of his beloved Cantor. Rest in Peace, Dear Professor of Life!

  9. Amina Buhler-Allen

    John Conway, what a marvelous, playful, mischievous, yet thought-provoking mathematician. One of my most cherished friends and colleagues.

    In many ways, he retained that wonderful quality from childhood that most adults leave behind or forget.

    It was at Donald Coxeter’s home in Toronto where our paths first crossed. The official event : the dedication to H. S. M. Coxeter of Marc Pelletier‘s stainless steel 120-cell ( a 4-D dodecahedron, cell first projection) at the Field’s Institute in 2002.

    For many days we were welcomed into Coxeter’s home by Donald and his daughter, Susan Thomas. Encouraged to look through his library and letters, it turned into a mission of discovery and storytelling. Polyhedra, Escher prints and other delights adorned Coxeter’s house.

    Watching Conway interact with Donald, it was clear that they had a very special relationship. It was a hotbed for excited conversation.

    Conway, Coxeter, Pelletier-a mathematical tour of hyper space. A busying tour for those that didn’t live there. However, Marc did. It usually makes me dizzy. Speaking of which, John told me about a helmet that he had built as a student to simulate what It was like in the 4th dimension. He taught himself how to walk around campus that way.

    John’s family accompanied him on this trip. His son Gareth, three months old. Coxeter was mostly bedridden at this point, but mentally sharp. It was a math party of the highest order lasting many days.

    One night, the director of the Field’s took us all out to a very fancy restaurant to celebrate the event. After 4 -5 bottles of fine Canadian wine, the moment was perfect. John leaned over, “Marc, take off your shoe laces!” Conway proceeded to tie them together. My intent was to see what knot or “not knot’ John was using,
    my attention was turned. Meanwhile, the director took off his tie and began to tie the two of us together. Certainly we were turning well groomed heads at this ritzy place, but Marc and I were engaged in a feeble, tipsy attempt to get loose. I remember placing my leg over the director’s head. This is one of my most treasured math adventures.

    Marc and I designed hands-on math materials which is how we met. Marc Pelletier had already collaborated with Paul Hildebrandt on the “impossible“ injection mold which created the Zomeball. This modernized Steve Baer’s 31-zone system and discovery. Zometool was born on April 1, 1992-no joke. It can model hyper space polyhedra like the ones in Coxeter’s book , ‘Regular Polytopes’. Conway had many polyhedra models inside his office including Zometool models which he delighted in.

    Princeton also once had one of Pelletier’s 120-cell sculptures which was dedicated to Conway. John apologetically informed me that it was completely destroyed by drunken college students trying to play soccer.

    John was an avid Martin Gardner fan and contributed to Gardner’s recreational math column in Scientific American. The G4G ( Gathering for Gardner) Conference was always a highlight every 2 years. Conway would hold court in the sitting area outside the conference hall.

    Over the years we would be engaged in a game of trying to stump or out wit each other with a puzzle, linkage or such. He would see how long it would take for me to solve any given hands-on puzzle. It was like sparring. It always gave me great satisfaction when he delighted in a new idea or had trouble finding the solution. Then, I knew I was onto something. Sometimes I’d tempt him with puzzles which other friends had created-this leads to a story for elsewhere which includes both Conway and Penrose!

    The joy of math has been a game for me since childhood. Calculus was a marvelous dance. Finding and interacting with people that saw, played at hands-on math was a rare thing. It’s magic.

    There is such a thing as hands-on and recreational math. Surely, if more students were exposed to this method of discovery and learning, mathematics would and can become not a vexation but a wondrous delight and discovery. John made a large contribution in this area, exciting students with his math antics.

    John made reference that he did not want to be primarily remembered for the Game of Life. Instead, I’d like to suggest that he played his own 3-D & hyper version, every day.

    In John Conway‘s memory,
    keep it going…
    Let’s Play!!!

  10. Rob Superty

    Although I never had the privilege of meeting John Conway, it is undeniable that he more than any other has fueled my love for mathematics. I’m sure his work and legacy will always continue to inspire, educate, and entertain all who are fortunate enough to be touched by it.

  11. Robert Newcombe

    I remember him well from my days as a maths (we say maths, not math our side of the pond) student in Cambridge, England, 1967-70. Inspirational!

  12. Arun Sannuti '92

    Conway was my advisor for one of my JPs and my senior thesis. He thought I was a complete idiot, and compared to him, I am. But he taught me so much, and made me so thrilled to be in mathematics. I shall always remember losing to him constantly in backgammon.

    My favorite story about Professor Conway. When I knew him, he wasn’t all that interested in personal grooming, so he didn’t look or smell like a professor. At one point, I invited him to come to my eating club. We were early to dinner, and a number of my friends joined us on a large round table. After a while, with all of us talking, he decided that he was done, politely said goodbye and left. And all of my friends turned to me and one of them asked “Not that we mind, but why did you decide to invite a homeless person to dinner tonight?” And I had to explain that he was my thesis advisor and one of the most famous mathematicians in the world.

  13. Jeff Dozier

    Kohn’s comment—“Upon deciding on the topic in the car, Conway successfully gave the lecture without any additional preparation”—brings back a great memory. I shared a stage with Prof Conway sometime around 1992. Following a short panel discussion, each of us gave a talk. Conway had prepared his talk during the panel discussion, basing it on some patterns in design of the carpet on the floor.

  14. Bro. Patrick Carney

    I had the pleasure of working with John during three summers at DIMACS. Certainly, most of the tales related here ring true. But I would like to touch on another aspect of his life which might not be as well known.

    At the time, John lived above The Halo Pub. Three of us in our program and he went there to celebrate the birthday of one woman in our group. We sat at one of the few tables not only enjoying our ice cream, but being entertained by John’s stories and the various games he kept pulling out of the pocket of his shorts. We must have monopolized that table for well over an hour (fortunately most customers were interested in take-out). When it was finally time to go, he asked us to join him at a coffee house across the street at the corner that he apparently frequented. One of the regulars there was a woman who was down on her luck. But apparently John knew that in her day, she had been a very good artist. So he put us up to asking her to draw a little portrait of the birthday girl. The artist seemed to be delighted to be recognized and did indeed produce such a sketch. As John predicted, she perked up. It seemed to have made her night. I was really impressed by how this famous man had such a sensitive spot for a person many people would never notice. As much as I have always been impressed by his talks, stories, feats of his mind, etc., they have never told me as much about John as did his compassion for this older woman about whom he showed he really cared.

    I was later to learn from another person, that the people in that coffee shop did not know he was a professor. They just knew him as “John” who usually frequented the place in his shorts, tee shirt, and sandals. But I doubt that anyone who met him will ever forget him. I know I won’t. I hope now he is at peace and sharing Erdos’ book as they see the beautiful proofs.

  15. Diana Conway

    I absolutely loved reading all of these memories. Thank you everyone. For 24+ years I’ve been constantly buying socks, as John simply could not hold on to them. Will I ever stop looking at socks in stores and asking myself “Does John need socks?” Probably not.

  16. Julia Wermig-Morgan

    My dear friend from the “University of Belindas” the coffee and cake shop in Cambridge which formed a major part of my education when I was a research assistant there, and definitely some of the happiest bits. What happened to that wonderful solid real puzzle made for John by the Bell telephone company ? All stars and swirls going on into infinity? I so wanted to a set. Why
    has it never been made for sale?
    I have a big regret. I was even then interested in medicinal plants and actually thought to write to John to tell him elderberry juice seems to inhibit Covid-19 and mitigate the cytokine storm. I thought to email John and tell him but caught it myself, treated myself with elderberry (3 litres of elderberry cordial) survived the pneumonia and beginning of cytokine storm but by then the virus had got John. Please read my paper on researchgate all his friends and family and use it. I am trying to get people to do proper clinical trials.Diana, you must have loved John a lot to try and get him into socks. As a friend I have never seen him wear them.I did think they might be suitable for the Royal Society though.

  17. Michael Stranahan

    Michael Stranahan:

    In February, 2002, I was present at the dedication of Marc Pelletier’s six-foot diameter, stainless steel hyperdodecahedron which was hung in the main hall at the Fields Institute in celebration of Donald Coxeter’s lifelong contributions to Geometry.

    John Conway was one of the speakers at this event.

    A large audience sat in hushed expectation as John Conway rose to speak.

    John Conway had set up his moment perfectly.

    He began his remarks by saying Donald Coxeter had once tried to kill him.

    Audible gasps from the audience.

    Conway quickly explained that he was attending a mathematical lecture by Coxeter, and Coxeter had proposed an extremely interesting mathematical problem.

    The problem fascinated John and it took over his mind so completely that when he walked out of the lecture it had taken over all of his faculties.

    Lost in thought from grappling with Coxeter’s problem, Conway was crossing a street, and at the same moment that the problem’s solution hit him, he was also hit by a truck…

    And then then the relieved audience at the Fields Institute audience burst into delighted laughter and applause.

  18. Louis-Aimé de Fouquières

    Many engineers and scientists of France we saddened to learn of John Conway’s death. His name is known in several branches of mathematics, and one sometimes wondered if it was the same person.

    He played a last trick on us by choosing the day he left us. He was born on Doomsday, December 26, 1937, the day after Christmas, and he died on Doomsday, April 11, 2020, the day before Easter. His last sentence might have been: “Tomorrow is the day after Doomsday.” For us indeed, one world is over. What for him ? He often wore a shirt on which was written: “Schrödinger’s cat is not dead”.

  19. Priscilla Roberts

    I am a historian, not a mathematician, but I was quite a good friend of John Conway, at least towards the end of his life, and helped to organize one of his last international trips, to Hong Kong and Macau in April 2017. I’m not sure how much anyone else knows about that visit. So I’ve written down what I remember.
    John and I had met sometime one summer in the mid-1990s, when he helped me with my luggage on a train from Princeton to Washington, but lost touch until late 2016, when I spent a semester at the Institute for Advanced Study. We ran into each other at the Panera coffee shop, a regular early morning port of call for John and several others, including myself, who used to chat together and comment on the newspapers before going off to do whatever each of us was doing.
    John and I were both English and had been students at Cambridge, albeit a good many years apart, which gave us something in common, and he enjoyed talking about almost everything under the sun. John had already had at least one stroke and walked with some difficulty, using a stick, but was totally resolved to keep living an independent life, going in (usually on foot) to the Maths Department virtually every day that it was open. Very soon I came not just to enjoy his company but to admire his courage and vitality, plus his sheer bloody-minded determination to keep on going no matter what.
    With Christmas coming up, John was very pleased when I suggested that, since I could bring a guest to the Institute’s Christmas party, I’d like to invite him. That afternoon, we took the Institute’s shuttle bus, which stopped very close to the Panera coffee shop. I had not told anyone who I was bringing, but once we arrived, I was of course decidedly overshadowed by him. For decades, the Institute had been a favourite stamping ground of John’s, so he was something of a star of the show. We found a comfortable table with extra seating, where John held court as friends and acquaintances came over to see him, while I kept him well supplied with snacks and champagne. I realized just what a local institution John was when the taxi driver who took him home that evening later told me, “Everyone knows Professor Conway. He’s one of the smartest men in the world.”
    I left Princeton in January 2017, to take up a position at City University of Macau. John had travelled to many places but never been to either Macau or Hong Kong, so I said that I’d try to discover if there was any chance of bringing him out to give some visiting lectures. Somewhat to my surprise, my new university approved the idea and I was able to put together a 2-week package that allowed him to spend a week in each city.
    John arrived in April 2017 on Easter Sunday, declining the wheelchair United Airlines had arranged for him and coming into the arrival hall at Hong Kong airport on his own steam. The first thing he said to me when he saw me was that when I left Princeton, he had never thought any such trip would really happen. To which I could only reply, You know, neither did I.
    John’s schedule in Macau was rather complicated, as he shuttled between three different universities, giving lectures in each. Arrangements were sometimes a bit chaotic. John was 79 and sometimes tired, but to my admiration and amazement he never complained, even when he had to change accommodation several times, or a hotel restaurant was closed for a special event and he had to rely on me to raid a local supermarket and produce a makeshift scratch meal. He was indeed remarkably undemanding. So long as he had a pad of paper and a pencil for mathematical calculations and an enjoyable book to read, he was quite content. Keeping a famously disorganized man united with his passport, wallet, watch, and mobile phone was a constant minor logistical challenge, but what had been mislaid always eventually reappeared from whatever alternative dimension or universe it had temporarily relocated to.
    The great reward came in watching John give his lectures and seeing how his audience reacted. When he spoke at the University of Macau, the organizers asked me to orchestrate an interview format in which I would prompt him with questions to which he could respond at length. That meant I could watch the audience, which included classes of high-school students, as well as university students and academics. Their concentration and the rapt expression on many of their faces, as John explained his free will theorem and where he thought Einstein had got things wrong, was something I shall never forget. And one Chinese graduate student in particular was an ardent disciple, who spent hours talking maths with John when he had free time.
    After seven days John took the ferry to Hong Kong, to spend his second week at the Education University of Hong Kong. The mathematician who picked us up turned out to have been a graduate student of one of John’s closest friends. Much to my relief, throughout his last week John stayed in the very comfortable Marriott Hotel. Asked by his hosts in advance what they could do to entertain him, I see that I replied that, while he had never been to Hong Kong before so would probably like to see something of the place, “I suspect that what would keep him happiest, when he is not actually giving his public lectures, is to be set up in an office in your department, with a blackboard and some chalk, with people (academics, students, etc.) free to drop in on him ad lib and talk to him informally about Maths of every kind.” So that was what happened. Every day, someone picked him up and drove him to the Maths Department, where he conducted something of an impromptu seminar.
    Once I had seen John safely installed in his hotel, I had to return to Macau to teach for most of the week, while he spoke at the Education University and the HK Princeton Club. But I came back on his last full day, when he gave his final big lecture. I found John happily ensconced in an office, complete with blackboard, chatting to one or two other mathematicians. People from all over Hong Kong made their way to his lecture—I remember one French graduate student had spent several hours travelling there. John produced a bravura performance, answered questions, and when the event was over spent quite a bit of time explaining the concept of surreal numbers to a young female student. We went on to an excellent farewell banquet, which he enlivened by demonstrating magic tricks. The next day, he flew back to Princeton.
    Even at the time, I was rather awed that John was willing to fly halfway around the world (economy class at that) to places where he had never been before and really only knew one person, myself. Looking back, I feel honoured that he (and his wife Diana) trusted me enough to let me arrange his trip. It was a privilege that he came here.
    And soon afterwards, I would be exceptionally glad that I had made the effort when I did. John was indomitable but unfortunately not indestructible. In November 2017, less than seven months later, he had another stroke, which meant his travelling days were over. And on Easter Sunday three years later, I learned that he was gone. I wish John had remained in better health for longer. But I was very lucky to have the chance to know him.

  20. Steve R

    I learned of John’s passing and was part of the group that always saw him at the coffee house on Witherspoon St. ….I never beat him at backgammon!

  21. Stuart Pawley

    Our paths crossed just once when I, a physicist, dared to go to the Maths Soc at Cambridge as I had just discovered the 5 tetrahedra. John and I were both in our second year, and he was so clearly the focus of attention at the meeting. This meeting, specifically on mathematical models, started me on my tour of the triacontahedron and it’s stellations, which I enumerated in a paper a decade later with encouragement from H S M Coxeter. Seeing the progress of John’s career has been fascinating, especially when I was fully engaged in the development of parallel computation, when all the cellular automata models seemed like magic.
    The sad news of John’s passing came while I was making more stellations of the triacontahedron of a form I had not dreamed of before, which we could share in John’s memory.

  22. Bob Weaver

    this knot is only theory not factual, as if you were to take a circle as in topology and try to recreate this image it would be impossible simply stated, the one and only way to create this object would be to have the design laid out with a linear string than, recreate the design by joining both ends butting together and using a fastener like glue to the now finished product. It`s not mathematics, it`s a created mess by a group of highly intelligent overachievers telling the common people with common sense, we are smarter than you are, wrong again, a knot of this design is not possible for any use and you proved that point.

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