## Reykjavik nights [book review]

Posted in Books, Travel with tags , , , , , , , , on March 26, 2016 by xi'an

While this is the latest book in the Erlendur series by Icelandic author Arnaldur Indriðason, Reykjavik Nights [or Reykjavíkurnætur] is also the earliest in the chronology of the series since it relates to the first years of Erlendur in the Icelandic police and to murders that took place in 1974 in Reykjavik. The book may appeal mostly to those who have already read (the) other books in the series, as it explains very little about Erlendur’s past and the reasons he is so fascinated by missing persons. It is however a great read, despite or thanks to very little action when touring the nights of Reykjavik and arresting drunks weekend after weekend. (There is a slight interlude when Erlendur takes part in policing the 1100 anniversary celebrations of the settlement of Iceland at Þingvellir where the Alþing, the original Icelandic parliament stood.) Actually, I find the detective part less than convincing but it hardly matters since the development of the character of Erlendur is very well conducted. With a constant focus throughout the series on themes like domestic violence and drunkenness. A very pleasant read.

## a glacial PhD in Iceland [job announcement]

Posted in Kids, Mountains, pictures, Statistics, Travel, University life with tags , , , , , , on February 3, 2016 by xi'an

[Here is a PhD offer at the University of Iceland that may be of interest to some readers or their students. I would have been interested 30 years ago!]

The Department of Mathematics at the University of Iceland (UI) seeks applicants for a fully funded 3 year PhD position for the project Statistical Models for Glaciology.

The student will develop Bayesian hierarchical spatio-temporal models to the field of glaciology, working with a consortium of experts at the University of Iceland, the University of Missouri and the Norwegian University of Science and Technology. The key people in the consortium are Prof. Birgir Hrafnkelsson at UI, Prof. Chris Wikle, and Prof. Håvard Rue, experts in spatial statistics and Bayesian computation. Another key person is Prof. Gudfinna Adalgeirsdottir at UI, an expect in glaciology. The Glaciology group at UI possesses extensive data and knowledge about the Icelandic glaciers.

The application deadline is February 29, 2016.

Detailed project description

## AISTATS 2016 [call for submissions]

Posted in pictures, Statistics, Travel, University life with tags , , , , , , , , , , , , on August 21, 2015 by xi'an

At the last (European) AISTATS 2014, I agreed to be the program co-chair for AISTATS 2016, along with Arthur Gretton from the Gatsby Unit, at UCL. (AISTATS stands for Artificial Intelligence and Statistics.) Thanks to Arthur’s efforts and dedication, as the organisation of an AISTATS meeting is far more complex than any conference I have organised so far!, the meeting is taking shape. First, it will take place in Cadiz, Andalucía, Spain, on May 9-11, 2016. (A place more related to the conference palm tree logo than the previous location in Reykjavik, even though I would be the last one to complain it took place in Iceland!)

Second, the call for submissions is now open. The process is similar to other machine learning conferences in that papers are first submitted for the conference proceedings, then undergo a severe and tight reviewing process, with a response period for the authors to respond to the reviewers’ comments, and that only the accepted papers can be presented as posters, some of which are selected for an additional oral presentation. The major dates for submitting to AISTATS 2016 are

 Proceedings track paper submission deadline 23:59UTC Oct 9, 2015 Proceedings track initial reviews available Nov 16, 2015 Proceedings track author feedback deadline Nov 23, 2015 Proceedings track paper decision notifications Dec 20, 2015

With submission instructions available at this address. Including the electronic submission site.

I was quite impressed by the quality and intensity of the AISTATS 2014 conference, which is why I accepted so readily being program co-chair, and hence predict an equally rewarding AISTATS 2016, thus encouraging all interested ‘Og’s readers to consider submitting a paper there! Even though I confess it will make a rather busy first semester for 2016, between MCMSki V in January, the CIRM Statistics month in February, the CRiSM workshop on Eatimating constants in April, AISTATS 2016 thus in May, and ISBA 2016 in June…

## Einvígið [book review]

Posted in Books, Kids, Mountains, pictures, Travel with tags , , , , , , , , on August 17, 2015 by xi'an

In Roissy (De Gaulle) airport, prior to catching my flight to Seattle, I noticed a “new” Indriðason‘s novel, Le Duel (Einvígið), that has not yet been translated into English. But just translated into French! This is a most unusual novel in the Erlendur series, in that the central character of the series only appears as a young cop in the final lines of the novel. Instead, the mentor of Erlendur, Marion Biem, is conducting an inquiry as to who had killed a young man in an almost empty Reykjavik cinema. Where almost all spectators seemed to have something to hide, if not always a murder… A classical whodunnit?! Not really because this happens in 1972, during the famous Fisher-Spassky duel, and that duel is unrelated to the murder, while the Icelandic police seems overwrought by the event and the presence of Russian and American double-agents in Reykjavik…

I found the whole exercise interesting, creating a sort of genealogy in the Erlendur series, with Marion’s mentor playing a side role and his early training in Glasgow (of all places!), with the re-creation of a 1972 Iceland and the chess match between Fisher and Spassky at the height of the Cold War. Plus a reminder about the tuberculosis epidemics of the 1930’s, where  The detective side of the novel is however less convincing than usual, with clues and fingerprints appearing at the most convenient times. And a fairly convoluted resolution. Still worth reading, especially on a long flight!

## Mýrin aka Jar City [book review]

Posted in Books, Mountains, pictures, Travel with tags , , , , , , , , , , on July 26, 2015 by xi'an

Mýrin (“The Bog”) is the third novel in the Inspector Erlendur series written by Arnaldur Indridason. It contains the major themes of the series, from the fascination for unexplained disappearances in Iceland to Elendur’s inability to deal with his family responsibilities, to domestic violence, to exhumations. The death that starts the novel takes place in the district of Norðurmýri, “the northern marsh”, not far from the iconic Hallgrimskirkja, and not far either from DeCODE, the genetic company I visited last June and which stores genetic information about close to a million Icelanders, the Íslendingabók. And which plays an important and nefarious role in the current novel. While this episode takes place mostly between Reykjavik and Keflavik, hence does not offer any foray into Icelandic landscapes, it reflects quite vividly on the cultural pressure still present in the recent years to keep rapes and sexual violence a private matter, hidden from an indifferent or worse police force. It also shows how the police misses (in 2001) the important genetic clues for being yet unaware of the immense and frightening possibilities of handling the genetic code of an entire population. (The English and French titles refer to the unauthorised private collections of body part accumulated [in jars] by doctors after autopsies, families being unaware of the fact.) As usual, solving the case is the least important part of the story, which tells about broken lifes and survivors against all odds.

## Einstök

Posted in pictures, Travel, Wines with tags , , , , , , on July 12, 2015 by xi'an

## dynamic mixtures [at NBBC15]

Posted in R, Statistics with tags , , , , , , , , , , , , on June 18, 2015 by xi'an

A funny coincidence: as I was sitting next to Arnoldo Frigessi at the NBBC15 conference, I came upon a new question on Cross Validated about a dynamic mixture model he had developed in 2002 with Olga Haug and Håvård Rue [whom I also saw last week in Valencià]. The dynamic mixture model they proposed replaces the standard weights in the mixture with cumulative distribution functions, hence the term dynamic. Here is the version used in their paper (x>0)

$(1-w_{\mu,\tau}(x))f_{\beta,\lambda}(x)+w_{\mu,\tau}(x)g_{\epsilon,\sigma}(x)$

where f is a Weibull density, g a generalised Pareto density, and w is the cdf of a Cauchy distribution [all distributions being endowed with standard parameters]. While the above object is not a mixture of a generalised Pareto and of a Weibull distributions (instead, it is a mixture of two non-standard distributions with unknown weights), it is close to the Weibull when x is near zero and ends up with the Pareto tail (when x is large). The question was about simulating from this distribution and, while an answer was in the paper, I replied on Cross Validated with an alternative accept-reject proposal and with a somewhat (if mildly) non-standard MCMC implementation enjoying a much higher acceptance rate and the same fit.