Archive for industrial ruins

“too dangerous to release” [a correct prediction]

Posted in Books, Travel with tags , , , , , , , , , , , , on July 9, 2026 by xi'an

Nature of 26 May had a long report on how the Mythos model is deemed to be too dangerous by its conceptor, Anthropic, to be publicly released, but instead shared with a limited number of organisations of their own choice. The argument being that Mythos was able to spot security flaws in every operating system and web browser on the market. But, sooner or later, the AI will prove accessible to a hacker who manages to penetrate one of these organisations, won’t it?! As pointed out by Nature’s writers, the natural question is why should firms be left to decide on who gets access to their software and how dangerous they are. The same writers also muse about governments imposing prohibitions on the firms, including outside their country. Which is exactly what happened a few weeks later on 12 June with the Trump administration “suspend[ing] all access to both Fable 5 and Mythos 5 by any foreign national, whether inside or outside the United States” with little factual argumentation. Another illustration of the short-sighted, knee-jerk, inconsistent, policies of that joke of an administration that does not address the real issue.

beauty and the ruins (2)

Posted in Books, pictures, Travel with tags , , , , , , , , , , , on July 8, 2025 by xi'an

beauty and the ruins (1)

Posted in Books, pictures, Travel with tags , , , , , , , , , , , on July 7, 2025 by xi'an

another Bernoulli factory

Posted in Books, Kids, pictures, R, Statistics with tags , , , , , , on May 18, 2020 by xi'an

A question that came out on X validated is asking for help in figuring out the UMVUE (uniformly minimal variance unbiased estimator) of (1-θ)½ when observing iid Bernoulli B(θ). As it happens, there is no unbiased estimator of this quantity and hence not UMVUE. But there exists a Bernoulli factory producing a coin with probability (1-θ)½ from draws of a coin with probability θ, hence a mean to produce unbiased estimators of this quantity. Although of course UMVUE does not make sense in this sequential framework. While Nacu & Peres (2005) were uncertain there was a Bernoulli factory for θ½, witness their Question #1, Mendo (2018) and Thomas and Blanchet (2018) showed that there does exist a Bernoulli factory solution for θa, 0≤a≤1, with constructive arguments that only require the series expansion of θ½. In my answer to that question, using a straightforward R code, I tested the proposed algorithm, which indeed produces an unbiased estimate of θ½… (Most surprisingly, the question got closed as a “self-study” question, which sounds absurd since it could not occur as an exercise or an exam question, unless the instructor is particularly clueless.)

CRAN does not validate R packages!

Posted in pictures, R, University life with tags , , , , , , , , , , on July 10, 2019 by xi'an

A friend called me the other day for advice on how to submit an R package to CRAN along with a proof his method was mathematically sound. I replied with some items of advice taken from my (limited) experience with submitting packages. And with the remark that CRAN would not validate the mathematical contents of the associated package manual. Nor even the validity of the R code towards delivering the right outcome as stated in the manual. This shocked him quite seriously as he thought having a package accepted by CRAN was a stamp of validation of both the method and the R code. It would be nice of course but would require so much manpower that it seems unrealistic. Some middle ground is to aim at a journal or a peer community validation where both code and methods are vetted. Which happens for instance with the Journal of Computational and Graphical Statistics. Or the Journal of Statistical Software (which should revise its instructions to authors that states “The majority of software published in JSS is written in S, MATLAB, SAS/IML, C++, or Java”. S, really?!)

As for the validity of the latest release of R (currently R-3.6.1 which came out on 2019-07-05, named Action of the Toes!), I figure the bazillion R programs currently running should be able to detect any defect pretty fast, although awareness of the incredible failure of sample() reported in an earlier post took a while to appear.