Great! I have been invited to take part in the Challenges and Advances in High Dimensional and High Complexity Monte Carlo Computation and Theory workshop (12w5105) in BIRS, Banff, next March. Given the participants confirmed so far, the prospect of meeting with “leading researchers who work at the cutting edge of scientific research in physics, chemistry, computer science, genetics and medicine”, and the fantastic facilities provided by BIRS, it is obviously a great opportunity to exchange and progress about the current state of the Monte Carlo methods (in Statistics), about a month before the workshop we organise on a similar theme at ICMS, Edinburgh, with Mark Girolami and Antonietta Mira. I am definitely and eagerly looking forward to this “MCMCanff” event! (And of course to the pleasure of discovering Banff and the nearby mountains in the winter!)
Archive for August, 2011
Banff workshop
Posted in Mountains, Statistics, Travel, University life with tags Banff, BIRS, Canada, Edinburgh, ICMS, MCMC, Monte Carlo Statistical Methods, Scotland, workshop on August 29, 2011 by xi'ant’was a dark and stormy night [not yet]
Posted in pictures with tags sunset, thunderstorm on August 28, 2011 by xi'an
AISTATS 2012 [call for papers]
Posted in Statistics, University life with tags AISTATS, artificial intelligence, Canary Islands, computer science, machine learning, Statistics on August 28, 2011 by xi'anThe Fifteenth International Conference on Artificial Intelligence and Statistics (AISTATS) is held on April 21-23, 2012, in La Palma, Canary Islands. (Although I cannot attend AISTATS, as it is just before our ICMS workshop on advanced MCMC methods, April 23-25, I will be an area chair for the selection of papers.) Here is the call for papers: Continue reading
Le Monde puzzle [#737 re-read]
Posted in R with tags Le Monde, mathematical puzzle on August 27, 2011 by xi'an
As a coincidence, while I was waiting for the solution to puzzle #737 published this Friday in Le Monde, the delivery (wo)man forgot to include the weekend magazine and I had to buy it this morning with my baguette (as if anyone cares!). The solution is (y0,z0,w0)=(38,40,46) and…it does not work! The value of (x1,y1,z1,w1) is indeed (19,39,43,8.5). Now, it does not work because the update mechanism used by the writers of the Le Monde column is to move all positions simultaneously, rather than one at a time: the update thus reads as
if un=(xn,yn,zn,wn), for i=1,…,4,
if uin-1 is not the maximum of un-1 and
otherwise.
(to compare with my earlier proposal). In this new configuration, the core of the R code I use is
[sourcecode language=”r” gutter=”false”]
while (nodd){
nsuite=suite=start=c(0,sort(2*sample(1:23,3)))
for (t in 1:20){
#some values of start never produce non-integer values
#of suite and never visit suite[1]=0
nsuite[-4]=(suite[-4]+suite[-1]+48*(suite[-1]-suite[-4]<0))/2
nsuite[4]=(suite[4]+suite[1]+48*(suite[1]-suite[4]<0))/2
suite=nsuite%%48
if ((suite[1]==0)||(max(is.decimal(suite))==1)){
nodd=(max(is.decimal(suite))==1)
print(t)
break()}
}}
[/sourcecode]
This new version leads to solutions (unsurprisingly!), returning
[sourcecode gutter=”false”]
> print(start)
[1] 0 12 24 36
[/sourcecode]
as one solution in 8 steps and
[sourcecode gutter=”false”]
> print(start)
[1] 0 38 40 46
[/sourcecode]
as the quickest solution in 6 steps.
Diamond age
Posted in Books, pictures with tags Anathem, Charles Dickens, cyberpunk literature, Diamond Age, Neil Stephenson, Robert van Gulik, Snow Crash, steampunk, suspension of disbelief, The Baroque Cycle, Turing, William Gibson on August 27, 2011 by xi'an
Here is the one before last of my vacation reads! As obvious from several earlier posts, I am a big fan of Neal Stephenson’s books. e.g. Snow Crash is one of my preferred cyberpunk books (along with Neuromancer), and I consider Stephenson’s approach to the genre deeper and more scientific than Gibson‘s. So when in Lancaster I picked the Diamond Age, I was quite excited to have discovered an overlooked volume of his’! The more because the story was partly taking place in Shanghai. Alas, I am rather disappointed by the result. Indeed, the book does not read well: the “suspension of disbelief” does not operate.
The Diamond Age brims with (too many???) brilliant techno-societal ideas, colourful characters, literary references, and exciting settings, but the plot dries out much too quickly. The universe Stephenson depicts is a mix of cyberpunk centred on nanotechnologies and of steampunk with Victorian codes and attitudes. (In a sense, the Diamond Age is Dickens mixed with Gibson and van Gulik.) One of the great ideas in the Diamond Age is the “primer” that educates the central character, Nell, who has been neglected by her alcoholic mother. It is a quite compelling concept, the one of an interactive book backed by an AI and by real actors that turn Nell into a real scientist (the part about Turing machines is quite good) and cryptographer, as well as teach Chinese orphans (although it does not work so well in the latter case because of the lack of real actors). The fact that the level of the story remains one of a fairy tale while Nell is growing up and maturing is a bit of a disappointment. What really put me off, though, half the book read, is the appearance of the Dreamers, an “unnecessary and monstrously tacky underwater sex cult” that doomed my “suspension of disbelief” for the rest of the book… (The criticisms are mostly positive, though.)
