Archive for Austria

truly and uniquely pseudo-random?

Posted in Books, pictures, Statistics, Travel, University life with tags , , , , , , , , , , , , , on July 10, 2024 by xi'an

I came across a Web paper entitled The Impact of Google’s Random Number Generator on Accurate Results that I found most puzzling in failing to explain the specific nature of this random generator and that included gems as below

“PRNGs (…) outputs are inherently predictable given a specific seed value, thus deviating from true randomness”

or stating that linear congruential generators suffered from “discernible patterns”, or yet advancing a bonus in using Google’s generator for “leveraging Gaussian distributions”… Referring to a specific and possibly obscure arXival proposing to construct (yet) a PRNG by reinforced learning, with an objective function based on randomness tests reminded me of Marsaglia’s Die Hard. And to “true randomness”. Plus being repetitive and obsequious. Until I found the piece was “written” by Quthor with no typo, an AI “writer” powered by Quick Creator. I should have paid more attention to the level of nonsense…

On the same occurrence, I also read a recent Scientific American paper on randomness tests pseudo-random number generators by Christopher Lutsko. Which does not start that well, since it reproduces the Laplace démon’s argument that a die roll outcome is not random. Also repeating the above pleonasm that PRNGs are not random since they are deterministic. And failing to not mention lava generators! The core of the article is however about recent papers by the author and Niclas Technau of the only examples of sequences that prove passed extremely strong pseudorandom tests. They focus on tests based on gap distribution and pair correlation.

“The [gap distribution] measures the size of the gaps between the points, and the [pair correlation’ measures the clustering of the points—how much they group up or stay apart (…) If these agree with what we would expect from random data, we say that the gap distribution or pair correlation is “Poissonian”.”  Christopher Lutsko

Along with Athanasios Sourmelidis, they proved that exponential sequences {α exp(θ log[n]) mod 1} have Poissonian pair correlation when θ<⅓, for any value of α. And higher Poissonian correlations for θ “smaller and smaller“. (This does not come out of the blue, as the proof relates to Van der Corput’s method of exponential sums, with links to the leading Austrian random generator community.) This is definitely an achievement. However, when θ gets “smaller and smaller“, the terms in the sequence grow more and more slowly, which forces calling for larger and larger values of α to make the generator useful. And the pseudo-randomness test based on Poissonian correlations is only one of many from the toolbox, so the debate seems far from over.

 

 

a journal of the conquest, war, famine, and death year

Posted in Books, Kids, pictures, Statistics, Travel, University life with tags , , , , , , , , , , , , , , , , , , , , , on July 11, 2023 by xi'an

Read Les chiens et la charrue (Le cycle de Syffe, tome 3 ) by Patrick K. Dewdney, which came out after a long hiatus (esp. when missing the parution in September 2021!). It thus proved hard to remember the complex structure of this universe, as well as the names of characters from the earlier volumes. But after one slow third of the book, including an endless river slog, the right pace set in and I read the remaining 400 pages quite quickly (the trip to Jeddah helped!), with a climactic ending, despite a few too many coincidences. Looking forward the next tome, next year maybe?! While still being stuck in the (disappointing) last tome of Christelle Dabos’ The Mirror Visitor, I read another Max Gladstone’s, Dead Country (The Craft War I), within a few days, despite some weaknesses in the style (heavy infodump disguised as teacher/pupil conversations) and in the story. Unsure I will pursue this series.Had an enjoyable early dinner at Otto, a Rue Mouffetard izayaka. Despite some highlights of the menu being unavailable, the remaining dishes were worth the visit! (And the bet that there would be a table available on a warm Saturday evening.)

Watched Korean Money Heist, which, I am told, is the K clone of La Casa de Papel (I had not watched). Very light and requiring a high tolerance for unlikely so unlikely twists, but with very good actors who managed to keep the pace till the last episode. With a appearance supposedly of the martyr city of Kherson, even though it is actually Hallstatt, Austria. (Just why would a North Korean student read Mayakovski’s poems in a Latin language while in Vladivostok?!)

Wünsche nach Mut und Ausdauer nach Wien

Posted in pictures, Travel with tags , , , , , , , on November 3, 2020 by xi'an

MCqMC 2022 in Linz, 17-22 July

Posted in Statistics with tags , , , , , , , on August 29, 2020 by xi'an

At the end of MCqMC 2020, held on-line with the amazing support of ICMS in Edinburgh, the next location was announced as being Linz, Austria, hosted by the Johannes Kepler Universität I visited a few years ago (with a memorable run up a nearby hill!). Hopefully this will take place for real as well as on-line, but my prior is rather non-informed at the moment…

Eidelwess Dunkel

Posted in Travel, Wines with tags , , , , , , on March 20, 2020 by xi'an