Archive for rock climbing

Astrostatistics school

Posted in Mountains, pictures, R, Statistics, Travel, University life with tags , , , , , , , , , , , , , , , , , , , , , on October 17, 2017 by xi'an

What a wonderful week at the Astrostat [Indian] summer school in Autrans! The setting was superb, on the high Vercors plateau overlooking both Grenoble [north] and Valence [west], with the colours of the Fall at their brightest on the foliage of the forests rising on both sides of the valley and a perfect green on the fields at the centre, with sun all along, sharp mornings and warm afternoons worthy of a late Indian summer, too many running trails [turning into X country ski trails in the Winter] to contemplate for a single week [even with three hours of running over two days], many climbing sites on the numerous chalk cliffs all around [but a single afternoon for that, more later in another post!]. And of course a group of participants eager to learn about Bayesian methodology and computational algorithms, from diverse [astronomy, cosmology and more] backgrounds, trainings and countries. I was surprised at the dedication of the participants travelling all the way from Chile, Péru, and Hong Kong for the sole purpose of attending the school. David van Dyk gave the first part of the school on Bayesian concepts and MCMC methods, Roberto Trotta the second part on Bayesian model choice and hierarchical models, and myself a third part on, surprise, surprise!, approximate Bayesian computation. Plus practicals on R.

As it happens Roberto had to cancel his participation and I turned for a session into Christian Roberto, presenting his slides in the most objective possible fashion!, as a significant part covered nested sampling and Savage-Dickey ratios, not exactly my favourites for estimating constants. David joked that he was considering postponing his flight to see me talk about these, but I hope I refrained from engaging into controversy and criticisms… If anything because this was not of interest for the participants. Indeed when I started presenting ABC through what I thought was a pedestrian example, namely Rasmus Baath’s socks, I found that the main concern was not running an MCMC sampler or a substitute ABC algorithm but rather an healthy questioning of the construction of the informative prior in that artificial setting, which made me quite glad I had planned to cover this example rather than an advanced model [as, e.g., one of those covered in the packages abc, abctools, or abcrf]. Because it generated those questions about the prior [why a Negative Binomial? why these hyperparameters? &tc.] and showed how programming ABC turned into a difficult exercise even in this toy setting. And while I wanted to give my usual warning about ABC model choice and argue for random forests as a summary selection tool, I feel I should have focussed instead on another example, as this exercise brings out so clearly the conceptual difficulties with what is taught. Making me quite sorry I had to leave one day earlier. [As did missing an extra run!] Coming back by train through the sunny and grape-covered slopes of Burgundy hills was an extra reward [and no one in the train commented about the local cheese travelling in my bag!]


Gorges de la Bourne [jatp]

Posted in Mountains, pictures, Running, Travel with tags , , , , , , , , on October 12, 2017 by xi'an

Saoû [2]

Posted in Mountains, pictures, Travel with tags , , , on May 19, 2012 by xi'an

The Whitefire Crossing

Posted in Books, Mountains, Travel with tags , , , , on January 15, 2012 by xi'an

I grabbed The Whitefire Crossing (by Courtney Schafer) in the Barnes-and-Nobles of Provo, Utah, after one great day of ice-climbing and because of the nice cover! The main plot is about a smuggler+mountain guide taking a hidden mage away from a magicians’ city. The Whitefire is the mountain range the group must cross to reach a safe haven where magic is banned. The first part of the book is quite enticing, taking place in the mountains with several stories of climbs and rescues. There is however a limit on the number of climbs you can describe in a book and the second part of The Whitefire Crossing is more tepid, in my opinion. This is the author’s first book and the way characters interact with one another somehow reflects upon this. The plot is indeed rather predictable and the very final twist not really unexpected. (The [unavoidable] love relation is clear to anyone but the main character from the very beginning of the book!) The cover is also going against mountaineering (obvious) practice that the most experienced climber stands at the back when going down…   The Whitefire Crossing still remains an enjoyable book (I had to rescue over and over from my son’s room as  he kept stealing it from me!) and I am looking forward the sequel, The Tainted City, as obviously are more enthusiastic reviewers, here and there. And there.

a B’day gift

Posted in Kids, Mountains with tags , on September 19, 2011 by xi'an

As a B’day gift, my daughter agreed to come climbing with me. A real gift! We had two hours of great climbing together in the local indoor club, with very few climbers that early in the morning. (The rib hurt a lot more than when running, though.)

Back on Morgiou

Posted in Kids, Mountains with tags , , , , , on July 15, 2010 by xi'an

I went back climbing to Morgiou on Saturday night, achieving an easy 5c there but my son was in a hurry to get back to CiRM to watch the (football) game, so we did not try anything else. We started at 7pm, so the temperature was quite enjoyable. Too bad there is not another window of opportunity before I leave!

Climbing in Morgiou

Posted in Kids, Mountains with tags , , , , , on July 10, 2010 by xi'an

On Thursday evening, my son and I went climbing—along with Jean-Michel Marin who took those pictures—in the vale of Morgiou, on a spot called Royaume de dégun (dégun meaning nobody in the local provencal dialect, the name is apparently borrowed from a book by Gilles Del Pappas with the same name published in 2002). As we were in a hurry for the evening meal, we only tried the easiest route (5a). It took us a while to find the way into this small cirque, although it  is only 20mn from CiRM,  and it also took some pondering before going through the swarm of bees that elected the rock crack next to the path as home… But the nice thing was that, by 6pm, the rock was in blessed shade. The limestone rock is fairly characteristic of the area, with tiny “water droplet” holes for fingers and a very good grip for the feet. Most of the routes (including one called théorème de l’engambi, like most routes there a reference to a book by a local author, not to a climb by a visiting mathematician) in this spot are 6a/6b, because the cliff starts to lean forward at the top. I hope we can find some time to go back and try the 5c routes…