ABC not in Svalbard [this time!]

Alas, thrice alas!, there will be no one attending the ABC in Svalbard in Svalbard  next April. As the travel conditions to and around Norway are getting tougher, it is just too unrealistic to expect traveling to the Far North even from Oslo. Too bad, but hopefully there will be another opportunity in a near enough future…

However, don’t give up the fight!, the mirror meetings in Brisbane and Grenoble are still planned to take place, along with an on-line version accommodating most of the speakers invited so far. Anyone interested in holding another mirror meeting?! Please contact me.

ABC in Svalbard [update]

Even though no one can tell at this stage who will be allowed to travel to Svalbard mid April 2021, we are keeping the workshop to physically take place as planned in Longyearbyen. With at least a group of volunteers made of researchers from Oslo (since at the current time, travel between mainland Norway and Svalbard is authorised). The conference room reservation has been confirmed yesterday and there are a few hotel rooms pre-booked through Hurtigrutensvlabard.com. Anyone planning to attend just need to (i) register on the workshop webpage, (ii) book an hotel room for the duration of the workshop (or more)., and (iii) reserve a plane ticket as there are not that many flights planned.

Obviously this option should only attract a few brave souls (from nearby countries). We are thus running at the same time three mirror workshops in Brisbane (QUT), Coventry (University of Warwick), and Grenoble (IMAG & INRIA). Except for Warwick, where the current pandemic restrictions do not allow for a workshop to take place, the mirror workshops will take place in university buildings and be face-to-face (with video connections as well). Julyan Arbel has set-up a mirror webpage as well. With a (free) registration deadline of 31 March, the workshop being open to all who can attend. Hopefully enough of us will gather here or there to keep up with the spirit of the earlier ABC workshops. (To make the mirror places truly ABCesque, it should have been set in A as Autrans rather than Grenoble!)

from Svalbard [with snow]

Metropolis in 95 characters

Here is an R function that produces a Metropolis-Hastings sample for the univariate log-target f when the later is defined outside as another function. And when using a Gaussian random walk with scale one as proposal. (Inspired from a X validated question.)

m<-function(T,y=rnorm(1))ifelse(rep(T>1,T),
  c(y*{f({z<-m(T-1)}[1])-f(y+z[1])<rexp(1)}+z[1],z),y)

The function is definitely not optimal, crashes for values of T larger than 580 (unless one modifies the stack size), and operates the most basic version of a Metropolis-Hastings algorithm. But as a codegolf challenge (on a late plane ride), this was a fun exercise.

ABC in Svalbard, April 12-13 2021

This post is a very preliminary announcement that Jukka Corander, Judith Rousseau and myself are planning an ABC in Svalbard workshop in 2021, on 12-13 April, following the “ABC in…” franchise that started in 2009 in Paris… It would be great to hear expressions of interest from potential participants towards scaling the booking accordingly. (While this is a sequel to the highly productive ABCruise of two years ago, between Helsinki and Stockholm, the meeting will take place in Longyearbyen, Svalbard, and participants will have to fly there from either Oslo or Tromsø, Norway, As boat cruises from Iceland or Greenland start later in the year. Note also that in mid-April, being 80⁰ North, Svalbard enjoys more than 18 hours of sunlight and that the average temperature last April was -3.9⁰C with a high of 4⁰C.) The scientific committee should be constituted very soon, but we already welcome proposals for sessions (and sponsoring, quite obviously!).