free fall [fake]

As I was looking for the location of a picture serving as a background image for Windows 10 log-in page, I came across several versions of the above, supposedly showing a climber failing to grab another climber’s hand and as a result falling. Or “falling” as the image is obviously doctored, most likely by removing the ropes securing both climbers. This is fairly ridiculous, from the top climber hanging by his hand to the bottom one carrying quickdraws on his harness, as in the worst climbing movies… Still, I wish the location of the shot was provided on the website. (As an insider joke, I had a fall when running that was definitely not fake during the Xmas vacations, scraping a fair amount of skin on the gritty sidewalk, but with no apparent lasting damage, although I am barred from running by a tendinitis which started in Warwick last month..!)

mare e monti [climbing up Rumpe Cuou]

While at CIRM for Bayes for Good and Big Bayes workshops, I went again climbing with Nicolas, a guide from Cassis. As we had picked a day when the mistral (a local Northeasterner) was high and made climbing unpleasant and freezing, Nicolas picked a domain on the `other’ side, that was completely protected and started from the sea and went up in the sun, the wind only hitting us at the top, after six pitches, most of which I managed to lead.

We proceeded fast enough to get down for a second route, just as pleasant, finishing at the top as the Sun was setting down behind the islands below us. A well-chosen set of levels (5b, 5c) and rock-types like slab for my level and a nice conslusion to three climbing outings within a month. (Note that most pictures of our route are not mine as my camera battery went down before we even started.)

sunset on Riou Island [jatp]

computational statistics and molecular simulation [18w5023]

 I truly missed the gist of the first talk of the Wednesday morning of our X fertilisation workshop by Jianfeng Lu partly due to notations, although the topic very much correlated to my interests like path sampling, with an augmented version of HMC using an auxiliary indicator. And mentions made of BAOAB. Next, Marcello Pereyra spoke about Bayesian image analysis, with the difficulty of setting a prior on an image. In case of astronomical images there are motivations for an L¹ penalisation sparse prior. Sampling is an issue. Moreau-Yoshida proximal optimisation is used instead, in connection with our MCMC survey published in Stats & Computing two years ago. Transferability was a new concept for me, as introduced by Kerrie Mengersen (QUT), to extrapolate an estimated model to another system without using the posterior as a prior. With a great interlude about the crown of thorns starfish killer robot! Rather a prior determination based on historical data, in connection with recent (2018) Technometrics and Bayesian Analysis papers towards rejecting non-plausible priors. Without reading the papers (!), and before discussing the matter with Kerrie, here or in Marseille, I wonder at which level of precision this can be conducted. The use of summary statistics for prior calibration gave the approach an ABC flavour.

The hand-on session was Jonathan Mattingly’s discussion of gerrymandering reflecting on his experience at court! Hard to beat for an engaging talk reaching between communities. As it happens I discussed the original paper last year. Of course it was much more exciting to listen to Jonathan explaining his vision of the problem! Too bad I “had” to leave before the end for a [most enjoyable] rock climbing afternoon… To be continued at the dinner table! (Plus we got the complete explanation of the term gerrymandering, including this salamander rendering of the first identified as gerrymandered district!)

Crêt Saint Michel

A great afternoon climbing near CIRM with Nicolas, a mountain guide from the local guide company in Cassis, on this cliff of Crêt Saint Michel I passed everyday [while there!] to go swimming in the Sormiou harbour below, a mere 15 mn run from CIRM. As shown by the above map of bolted routes on the first half of the cliff, there are plenty of choices and more, although there were already four other groups climbing on that afternoon.

All these routes are bolted and have been around for quite a while, meaning two significant things: the quotation of the difficulty of the routes is quite lax and the rock is weathered by use at places, which made going up a 5c route somewhat of a challenge for me when climbing second and an impossibility when climbing first. On the rightmost green route, the 6a+ part had bits where I had to rely on slings left by Nicolas.The weather was brilliant, with blue sky and hot sun all the way, and the view of the Sormiou calanque (creek) below as a terrific background… I hope I can repeat this experience when visiting CIRM again in November, for the “Big Bayes” conference. And even more that this unique coastline will not be reached by the growing oil spil in the area.