Archive for flight

Le Monde puzzle [#1083]

Posted in Books, Kids, R, Travel with tags , , , , , , on February 7, 2019 by xi'an

A Le Monde mathematical puzzle that seems hard to solve without the backup of a computer (and just simple enough to code on a flight to Montpellier):

Given the number N=2,019, find a decomposition of N as a sum of non-trivial powers of integers such that (a) the number of integers in the sum is maximal or (b) all powers are equal to 4.  Is it possible to write N as a sum of two powers?

It is straightforward to identify all possible terms in these sums by listing all powers of integers less than N

pool=(1:trunc(sqrt(2019)))^2
for (pow in 3:11)
  pool=unique(c(pool,(2:trunc(2019^(1/pow)))^pow))

which leads to 57 distinct powers. Sampling at random from this collection at random produces a sum of 21 perfect powers:

 1+4+8+9+16+25+27+32+36+49+64+81+100+121+125+128+144+169+196+243+441

But looking at the 22 smallest numbers in the pool of powers leads to 2019, which is a sure answer. Restricting the terms to powers of 4 leads to the sequence

1⁴+2⁴+3⁴+5⁴+6⁴ = 2019

And starting from the pools of all possible powers in a decomposition of 2019 as the sum of two powers shows this is impossible.

end of the Canadian Rockies [jatp]

Posted in Mountains, pictures, Travel with tags , , , , , , , , , on September 16, 2018 by xi'an

Canadian Rockies [jatp]

Posted in Mountains, pictures, Travel with tags , , , , , , , on August 11, 2018 by xi'an

yes, another potential satellite to ISBA 2018!

Posted in Statistics with tags , , , , , , , , , , on May 22, 2018 by xi'an

On July 2-4, 2018, there will be an ISBA sponsored workshop on Bayesian non-parametrics for signal and image processing, in Bordeaux, France. This is a wee bit further than Warwick (BAYsm) or Rennes (MCqMC), but still manageable from Edinburgh with direct flights (if on Ryanair). Deadline for free (yes, free!) registration is May 31.

only in India… [jatp]

Posted in pictures, Travel with tags , , , , , , , on January 21, 2018 by xi'an

Last time I visited India, I highlighted an advertisement for a machine-learning match-making system. This time, while eating a last aloo paratha for breakfast in Kolkata, I noticed ads for Hindu temples on the back of my Air India boarding passes which are actually run by the State of Gujarat rather than the temples themselves. (Gujarat is India’s westernmost state.)

flying over Afghanistan [jatp]

Posted in Mountains, pictures, Travel, University life with tags , , , , , , , on January 8, 2018 by xi'an

over the Bernese Alps [jatp]

Posted in Mountains, pictures, Travel with tags , , , , , , , , , on November 4, 2017 by xi'an

Great views of the Bernese and Grisonese Alps on both legs of my trip to and from Venezia. Flying over Les Diablerets, Bormio and many other places I visited over the years..