## Archive for flight

## a year ago, a world away

Posted in Statistics with tags Bristol, COVID-19, demonstration, England, flight, Greta Thunberg, pandemics, plane trip, seminar, Travel, United Kingdom, University of Bristol, Wales on February 24, 2021 by xi'an## Le Monde puzzle [#1083]

Posted in Books, Kids, R, Travel with tags arithmetics, flight, Le Monde, mathematical puzzle, Montpellier, R, Université de Montpellier 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 Air France, Canada, Canadian Rockies, flight, forest fire, jatp, JSM 2018, plane picture, smog, vacations on September 16, 2018 by xi'an## Canadian Rockies [jatp]

Posted in Mountains, pictures, Travel with tags Banff, Canada, Canadian Rockies, flight, JSM 2018, plane picture, Rocky Mountains, Vancouver on August 11, 2018 by xi'an## yes, another potential satellite to ISBA 2018!

Posted in Statistics with tags Bayesian nonparametrics, Bordeaux, Edinburgh, flight, France, French wine, image analysis, satellite workshop, signal, vineyard, workshop on May 22, 2018 by xi'an**O**n 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.