professor position at Warwick

Posted in Statistics with tags , , , , , , on January 21, 2021 by xi'an

dependable AI/ML [France is AI]

Posted in Statistics with tags , , , , , on January 21, 2021 by xi'an

Poiré de glace [entre pierre & terre]

Posted in Travel, Wines with tags , , , , , , on January 20, 2021 by xi'an

[o-l] ISBA 2021 [百花齊放,百家爭鳴]

Posted in pictures, Statistics, Travel, University life with tags , , , , , , , , , , , , , , on January 20, 2021 by xi'an

As usual, when looking for our ISBA World conference, ISBA [now] 2021, many alternative realities emerge, ISBA being such a popular acronym! The actual dates for the (true and only) ISBA 2021 conference are 28 June – 02 July and the location is no longer Kunming, China, since there is a pandemic going on!!! The conference is now on-line, which forces a complete rethinking of its organisation, away from a sheer replica on Zoom of the traditional conference. And with no registration fees!! I have agreed to join other ISBA members to contribute (with limited abilities) to this switch and obviously welcome comments towards it! Having greatly learned from the earlier experience with the One World Bernoulli+IMS conference last summer, thanks to the dedication and imagination of Leif Döring!, here are some line of thought:

  • Keep in mind days are 24 hours long and attention span much smaller, towards keeping the offer manageable for a fully engaged participant
  • Account and take advantage of the multiple time zones available to virtual participants to stretch the schedule to cover as many participants as possible, with a potential multiplication of (plenary) talks and posters
  • Avoid filling the on-line schedule with live talks but have them pre-registered, possibly with several levels of length and depth, including a one-slide two-minute version
  • Exploit on-line abilities to focus solely (?) on interactions, which is the main point of conferences, meaning participants joining for a thematic session over a reasonable duration to discuss talks or posters they had attended on their own before, with a catalyst leading the show with prepared questions
  • Preregister poster presentations as well, so that live poster sessions involve only questions and discussions, and group poster by theme (an attempt of mine at the earlier ISBA conferences) so that presenters and visitors can interact at the theme level rather than being stuck in an empty room with one’s poster
  • Create local mirrors when people could physically (safely!) gather to attend the conference, from watching videos and poster together to engage into a local plus virtual discussion during interaction sessions. I certainly plan to hold one such session in Paris [if there and not in Eindhoven on 28 June – 02 July]
  • Find ways to engage participants to fully commit to the conference (see above), for instance by preparing a “I am away at ISBA 2021” card one could post on whatever social or asocial networks one favours (but maybe not as one’s vacation email automated reply, unless the card is a few bytes…)

Kempner Fi

Posted in Books, Kids, R, Statistics with tags , , , , , , , on January 19, 2021 by xi'an

A short code-golf challenge led me to learn about the Kempner series, which is the series made of the inverted integers, excluding all those containing the digit 9. Most surprisingly this exclusion is enough to see the series converging (close to 23). The explanation for this convergence is that, citing Wikipedia,

“The number of n-digit positive integers that have no digit equal to ‘9’ is 8 × 9n−1

and since the inverses of these n-digit positive integers are less than 101−n the series is bounded by 80. In simpler terms, it converges because the fraction of remaining terms in the series is geometrically decreasing as (9/10)1−n. Unsurprisingly (?) the series is also atrociously slow to converge (for instance the first million terms sum up to 11) and there exist recurrence representations that speed up its computation.  Here is the code-golf version

n=scan()+2
while(n<-n-1){
F=F+1/T
while(grepl(9,T<-T+1))0}
F

that led me to learn about the R function grepl. (The explanation for the pun in the title is that Semper Fidelis is the motto of the corsair City of Saint-Malo or Sant-Maloù, Brittany.)