Archive for Germany

MaxEnt 2019 [last call]

Posted in pictures, Statistics, Travel with tags , , , , , , , on April 30, 2019 by xi'an

For those who definitely do not want to attend O’Bayes 2019 in Warwick,  the Max Ent 2019 conference is taking place at the Max Planck Institute for plasma physics in Garching, near Münich, (south) Germany at the same time. Registration is still open at a reduced rate and it is yet not too late to submit an abstract. A few hours left. (While it is still possible to submit a poster for O’Bayes 2019 and to register.)

trip to the past

Posted in Books, pictures with tags , , , , , , , , , on January 6, 2019 by xi'an

When visiting my mother for the Xmas break, she showed me this picture of her grand-father, Médéric, in his cavalry uniform, taken before the First World War, in 1905. During the war, as an older man, he did not come close to the front lines, but died from a disease caught from the horses he was taking care of. Two other documents I had not seen before were these refugee cards that my grand-parents got after their house in Saint-Lô got destroyed on June 7, 1944.

And this receipt for the tinned rabbit meat packages my grand-mother was sending to a brother-in-law who was POW in Gustrow, Germany, receipt that she kept despite the hardships she faced in the years following the D Day landing.

Max Ent at Max Plank

Posted in Statistics with tags , , , , , , , , , , on December 21, 2018 by xi'an

truncated Gumbels

Posted in Books, Kids, pictures, Statistics with tags , , , , , , , on April 6, 2018 by xi'an

As I had to wake up pretty early on Easter morning to give my daughter a ride, while waiting I came upon this calculus question on X validated of computing the conditional expectation of a Gumbel variate, conditional on its drifted version being larger than another independent Gumbel variate with the same location-scale parameters. (Just reminding readers that a Gumbel G(0,1) variate is a double log-uniform, i.e., can be generated as X=-log(-log(U)).) And found after a few minutes (and a call to Wolfram Alpha integrator) that

\mathbb{E}[\epsilon_1|\epsilon_1+c>\epsilon_0]=\gamma+\log(1+e^{-c})

which is simple enough to make me wonder if there is a simpler derivation than the call to the exponential integral Ei(x) function. (And easy to check by simulation.)

Incidentally, I discovered that Emil Gumbel had applied statistical analysis to the study of four years of political murders in the Weimar Republic, demonstrating the huge bias of the local justice towards right-wing murders. When he signed the urgent call [for the union of the socialist and communist parties] against fascism in 1932, he got expelled from his professor position in Heidelberg and emigrated to France, which he had to leave again for the USA on the Nazi invasion in 1940. Where he became a professor at Columbia.

oxwasp@amazon.de

Posted in Books, Kids, pictures, Running, Statistics, Travel, University life with tags , , , , , , , , , , , , , , , , , on April 12, 2017 by xi'an

The reason for my short visit to Berlin last week was an OxWaSP (Oxford and Warwick Statistics Program) workshop hosted by Amazon Berlin with talks between statistics and machine learning, plus posters from our second year students. While the workshop was quite intense, I enjoyed very much the atmosphere and the variety of talks there. (Just sorry that I left too early to enjoy the social programme at a local brewery, Brauhaus Lemke, and the natural history museum. But still managed nice runs east and west!) One thing I found most interesting (if obvious in retrospect) was the different focus of academic and production talks, where the later do not aim at a full generality or at a guaranteed improvement over the existing, provided the new methodology provides a gain in efficiency over the existing.

This connected nicely with me reading several Nature articles on quantum computing during that trip,  where researchers from Google predict commercial products appearing in the coming five years, even though the technology is far from perfect and the outcome qubit error prone. Among the examples they provided, quantum simulation (not meaning what I consider to be simulation!), quantum optimisation (as a way to overcome multimodality), and quantum sampling (targeting given probability distributions). I find the inclusion of the latest puzzling in that simulation (in that sense) shows very little tolerance for errors, especially systematic bias. It may be that specific quantum architectures can be designed for specific probability distributions, just like some are already conceived for optimisation. (It may even be the case that quantum solutions are (just next to) available for intractable constants as in Ising or Potts models!)

keine Angst vor Niemand…

Posted in Statistics with tags , , , , , , , on April 1, 2017 by xi'an

Berlin snapshot #3 [jatp?]

Posted in Books, pictures, Running, Travel with tags , , , , , , , on March 31, 2017 by xi'an