## a journal of the [second] plague year

Posted in Books, Kids, pictures, Travel, University life with tags , , , , , , , , , , , , , , , , , , , , , , , on April 10, 2021 by xi'an

Read the picaresque El Buscòn (in French, translated by Nicolas Restif de La Bretonne), dating from 1602-1604, but the classic French translation from a century later is quite enjoyable and the story often hilarious. (I read this book after reading in 2019 the BD (comics) by Alain Ayroles and Juanjo Guarnido called les Indes Fourbes, that was inspired from El Buscòn and pretended to produce its sequel, located in South America). Also read the second volume of Olen Steinhauer, The Confession, just as impressive a dig into the minutiae of a Balkanic socialist dictature as the first one. And into the complex mind of another militia inspector in the homicide squad. (Just wondering if there were truly paper cups in the post-war Eastern block!)

Made my first fresh pastas with the traditional pasta machine my daughter got me as a Xmas present! I need improvements but, despite the mess this creates (flour everywhere!), it is a real treat to eat fresh pastas. The next goal is to check if soba noodles can be made with the machine….

Watched some parts of a rather terrible Korean series, Demon Catchers (or The Uncanny Counter). With absolutely no redeeming feature, although a very popular show… And the beginning episodes of another SF Korean series, Alice,  playing with time travel themes until it hit the usual paradoxes. (At least the physics fomulae on the white boards sounded correct, even though the grossly romanticised home office of a physics professor made no sense.)

Gave up on Augusto Cruz’ London after Midnight. Which revolves around the search for a surviving copy of the 1927 horror movie London after midnight, made by Tod Browning, and seemingly cursed. The plot is terrible and the style awful, an unpalatable endless infodump… Read P. Djeli Clark’s delightful short story A Dead Djinn in Cairo, which is a prequel to Haunting of tramcar 105 about a supernatural Cairo in the early 1900’s.

## le manifeste des 343 [50 years ago]

Posted in Kids with tags , , , , , , , on April 5, 2021 by xi'an

## hands-on probability 101

Posted in Books, Kids, pictures, Statistics, University life with tags , , , , , , , , , on April 3, 2021 by xi'an

When solving a rather simple probability question on X validated, namely the joint uniformity of the pair

$(X,Y)=(A-B+\mathbb I_{A

when A,B,C are iid U(0,1), I chose a rather pedestrian way and derived the joint distribution of (A-B,C-B), which turns to be made of 8 components over the (-1,1)² domain. And to conclude at the uniformity of the above, I added a hand-made picture to explain why the coverage by (X,Y) of any (red) square within (0,1)² was uniform by virtue of the symmetry between the coverage by (A-B,C-B) of four copies of the (red) square, using color tabs that were sitting on my desk..! It did not seem to convince the originator of the question, who kept answering with more questions—or worse an ever-changing question, reproduced in real time on math.stackexchange!, revealing there that said originator was tutoring an undergrad student!—but this was a light moment in a dreary final day before a new lockdown.

## Sheer Thursday in Nature

Posted in Books, Kids, University life with tags , , , , on April 2, 2021 by xi'an

As on this (sheer or maundy) Thursday, it happens from time to time a religious tribune worms its way into the scientific journal Nature. This one calls for a collaboration between scientists and “people of faith” towards stalling climate change. Which is obviously well intentioned, as any initiative towards that goal cannot hurt on principle. But against the scientific method as well: the  tribune calls for convincing religious communities of the need to act by relating scientific facts to “sacred” texts, for focussing on communities of the same faith impacted by climate change, and never argue against anti-science religious arguments… And somewhat irrational even without considering the conservatism of most religious groups, as “people of faith” are about as diverse as the whole society.

## plusquamperfect squares

Posted in Books, Kids, R with tags , , , on April 2, 2021 by xi'an

For some perfect squares, when you remove the last digit, you get another perfect square. The first five perfect squares are 16, 49, 169, 256 and 361. What are the next three ones? Is there a more than perfect square other than 169 such that removing the last two digits returns a perfect square?

Writing an R code for plusquamperfect squares is straightforward and returns the following first 20 values

``` [1]         16         49        169        256        361       1444
[7]       3249      18496      64009     237169     364816     519841
[13]    2079364    4678569   26666896   92294449  341991049  526060096
[19]  749609641 2998438564
```

Adding the second constraint does not return a solution other than 169.