Archive for Warwick

sudoku break

Posted in pictures, R, Statistics with tags , , , , on December 13, 2013 by xi'an

sudo291113While in Warwick last week, one evening after having exhausted my laptop battery, I tried the following Sudoku (from Libération):

>   printSudoku(readSudoku("libe.dk"))
  +-------+-------+-------+
  | 4   6 |   2   | 3   9 |
  |   3   |       |   2   |
  | 7   2 |       | 5   6 |
  +-------+-------+-------+
  |       | 9 4 5 |       |
  | 5     | 7 6 2 |     1 |
  |       | 3 1 8 |       |
  +-------+-------+-------+
  | 6   9 |       | 1   3 |
  |   7   |       |   9   |
  | 3   1 |   9   | 4   7 |
  +-------+-------+-------+

and could not even start. As it happened, this was a setting with no deterministic move, i.e. all free/empty entries had multiple possible values. So after trying for a while and following trees to no obvious contradiction (!) I decided to give up and on the next day (with power) to call my “old” sudoku solver (built while at SAMSI), using simulated annealing and got the result after a few thousand iterations. The detail of the exploration is represented above, the two colours being code for two different moves on the Sudoku table. Leading to the solution

  +-------+-------+-------+
  | 4 8 6 | 5 2 1 | 3 7 9 |
  | 1 3 5 | 6 7 9 | 8 2 4 |
  | 7 9 2 | 8 3 4 | 5 1 6 |
  +-------+-------+-------+
  | 2 1 3 | 9 4 5 | 7 6 8 |
  | 5 4 8 | 7 6 2 | 9 3 1 |
  | 9 6 7 | 3 1 8 | 2 4 5 |
  +-------+-------+-------+
  | 6 2 9 | 4 8 7 | 1 5 3 |
  | 8 7 4 | 1 5 3 | 6 9 2 |
  | 3 5 1 | 2 9 6 | 4 8 7 |
  +-------+-------+-------+

I then tried a variant with more proposals (hence more colours) at each iteration, which ended up being stuck at a penalty of 4 (instead of 0) in the final thousand iterations. Although this is a one occurrence experiment, I find it interesting that having move proposals may get the algorithm stuck faster in a local minimum. Nothing very deep there, of course..!

sudo301113

EQUIP launch

Posted in Statistics, University life with tags , , , , , , on October 10, 2013 by xi'an

Today, as I was around (!), I attended the launch of the new Warwick research project EQUIP (which stands for Enabling quantification of uncertainty for inverse problems). This is an EPSRC funded project merging mathematics, numerical analysis, statistics and geophysics, with a primary target application [alas!] in the oil industry. It will start hiring four (4!) postdocs pretty soon. The talks were all interesting, but I particularly liked the idea that they were addressed primarily to students who were potentially interested in the positions. In addition, Mark Girolami gaves a most appreciated insight on the modelling of uncertainty in PDE models, connecting with earlier notions set by Tony O’Hagan, modelling that I hope we can discuss further when both in Warwick!

my first week at work

Posted in Running, Travel, University life with tags , , , on September 9, 2013 by xi'an

front of Coventry station, Jan. 26, 2012After attending the first day of the RSS annual conference in Newcastle, I took the train to Coventry to join the Department of Statistics at the University of Warwick (this may sound confusing, but the University of Warwick is located in Coventry, not in Warwick, 8 miles south, and not to be confused with Coventry University, which is a former polytechnic; it is located in Warwickshire, though, which is why it took this name) where I now have a part-time professor position.  I will thus be at the department a week at a time, every other five weeks or so, during the teaching terms, and I obviously look forward the huge opportunities to interact with faculty and students therein. The “first week at work” was quite smooth, not entirely surprising given my numerous previous visits to Warwick, with hardly any bureaucratic step in the instalment. This gave me the opportunity to start the revision of the Jeffreys-Lindley’s paradox paper for Philosophy of Science and to reconnoitre longer running routes…

Warwickshire snapshot

Posted in pictures, Running, Travel with tags , , on May 17, 2013 by xi'an

Westwood church

back to England

Posted in pictures, Travel, University life with tags , , , , on March 3, 2013 by xi'an

Clifton suspension bridge pile, Bristol, Sept. 28, 2012One month after I visited UCL-Gatsby and Warwick University, I am back this week in England for short visits to Bristol, Warwick, and Oxford. Presumably not with the same wonderful weather I enjoyed in Bristol during the Fall workshop.

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