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wbhart

2,458 karma · joined December 22, 2010

I am a computer algebra/computational number theory researcher. I spend most of my time maintaining the Flint C library, and the Nemo.jl and Singular.jl libraries. I also work on algorithms for fast arithmetic.

My favourite languages are C and Julia.

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wbhart··on YouTube will now show ads on all videos even if creators don’t want them
This is not workable in Germany. There are huge fines for running YouTube businesses without putting business details at every location your video appears on the internet.

German State administrators have sent out such fines simply because videos made in Germany (even in English) which have advertising do not carry such additional business information.

These administrators will not know, nor care if you are in the YouTube Partner Program or not. They will simply send out the fines, which could bankrupt a small hobbyist.

This affects me directly, and I would have to remove my hobby channel from YouTube if they go ahead with this.

wbhart··on The Secret Math Society Known as Nicolas Bourbaki
Everybody learns that at school, French or not (I certainly did in Australia). The set theory referred to here is very abstract.
wbhart··on The Secret Math Society Known as Nicolas Bourbaki
But how did Bourbaki influence elementary/middle school mathematics? Bourbaki mathematics is basically at the level of graduate school. Except in countries where a graduate degree is required to teach mathematics, I can't imagine how there would even be a connection between the two worlds. Is that the case in France?

Again, I'm not disputing what you are saying either, merely trying to understand what happened.

Is it still going on in French schools today? Or was it 60's/70's only?

wbhart··on The Secret Math Society Known as Nicolas Bourbaki
That's interesting. I'd seen Arnold's work on teaching mathematics, and I'm very much aware of the dry formalism in Bourbaki books. However, I was not aware of the Arnold-Serre debate.

But the thing that really caught my eye here is your claim that there were visible effects of Bourbakism polluting mathematics.

Do you have any examples or specifics of that "visible effect". My question is a genuine one, not a challenge to what you are saying.

wbhart··on Prevent person-to-person transmission of SARS-CoV-2
I think R0 for the flu is usually take to be in the range 1.4-1.6 and for the common cold, 2-3. It's significant that it is quite a bit over 1, as it wouldn't spread so effectively if not.

It's an exponential factor, so small differences in the value make a big difference.

On the other hand, R0 for SARS-Cov-2 has been estimated as high as 6 by some groups.

[1] https://en.wikipedia.org/wiki/Basic_reproduction_number

wbhart··on IBM completes successful field trials on Fully Homomorphic Encryption
Yes, I meant divide by 3 mod 7.
wbhart··on IBM completes successful field trials on Fully Homomorphic Encryption
You need encrypt(1) + encrypt(2). You would not be sent instructions to add 2. No information about what you are doing is sent, except the operations + and x.

As the comments in the article state, it's actually all done with operations on polynomials with encrypted coefficients. As + and x can be done on polynomials, it all works out.

The maths behind it is of course much more complicated.

As for a simple maths analogy, consider adding 1 + 2.

I'll encrypt your values by multiplying by 3 mod 7. So encrypt(1) = 3x1 mod 7 = 3 mod 7 and encrypt(2) = 3*2 mod 7 = 6 mod 7. Only the encrypted values are sent, along with the operations I want to perform on the values.

Now this scheme is homomorphic, as I can just add the encrypted values, encrypt(1) + encrypt(2) = 3 + 6 mod 7 = 2 mod 7. That is the only computation that would be done before sending back the result.

To decrypt it, I would have to divide by 2 mod 7 by 3, which gives me 3 (you can easily check that encrypt(3) = 2 mod 7). And indeed 1 + 2 = 3. So the decrypted answer is correct.

Of course this scheme is too easy to crack. The FHE scheme is not.

wbhart··on Who were the Hyksos? Strontium isotope analysis of remains from ancient Egypt
I'm aware that mainstream archaeologist don't find evidence of an exodus of "Jewish" people from Egypt via the Sinai into Caanan. I personally don't buy their arguments (no dung piles in the desert, no artifacts found, no identification of Mt. Sinai, etc.) But I accept that no evidence is no evidence.

There is, as far as I recall, evidence of an "exodus" of sorts of the Hyksos from Egypt, but not any (solid) evidence of it happening in the manner or time described in the Biblical account.

I'm not sure I buy the Israel = Hyksos theory anyway. But this gets fairly far from my question, which really related to what the authors of this particular paper allude to, but don't say explicitly. They use some fairly strident language to describe what it is they are not talking about. I was just curious what that was, and why.

wbhart··on Who were the Hyksos? Strontium isotope analysis of remains from ancient Egypt
I don't completely follow your second paragraph. Are the Philistines now believed to have been Hebrew? That's a development I wasn't aware of.

I'm also not clear how the use of Hyksos-style chariots by Ramesses II's is linked. The Hyksos rulers in Egypt were a couple of centuries earlier, right?

Anyhow, can you shed any light on the "the elite attendant to the rulers" and the "ethnic group with which they are associated" mentioned in the paper?

wbhart··on Who were the Hyksos? Strontium isotope analysis of remains from ancient Egypt
Right, but one presumes that Josephus (a later Jewish historian) identified the Hyksos with the Hebrews? And he used the priest Manetho's works as source material for that claim?

So I'm curious if that is what the authors of this new study claim to be refuting. I think so, but it's unclear since they deliberately decline to mention the race they are referring to. Perhaps I should have quoted the sentence from the paper that I'm referring to (principally), "During this paper, we only refer to the dynastic rulers as the Hyksos, not the elite attendant to the rulers nor that ethnic group with which they are associated."

From my History Channel knowledge (not expert in any way), there has been a revival of interest in identifying the Hyksos with the Hebrews due to the location of a signet ring in Avaris by the archaeologist Manfred Bietak with "Ykb Hr" (Jacob?) inscribed on it. There is also a tomb with a statue of a Hyksos ruler who seemed to be almost as important as Pharoah himself, complete with what appears to be a multicoloured raiment painted on the statue.

Armed with this dumbed down version of archaelogy my interest in the paper is piqued. But they aren't so clear what they are refuting.

wbhart··on Who were the Hyksos? Strontium isotope analysis of remains from ancient Egypt
The authors don't say which race the Hyksos have traditionally been associated with. Do they mean the Hebrews?

It is interesting that the strontium isotope analysis suggests they did not come from a single homeland, but were from a variety of locations across the near East.

I'm not sure I'm identifying the race they are referring to correctly (too many History Channel documentaries maybe). For example, I don't think the Hebrews are supposed to have had a homeland at that point in history.

Nonetheless, the evidence that a significant number of them spent their childhood outside the Nile Delta region does indicate that they were not a race of people who were born, grew up and lived in Egypt the whole time.

Is someone able to confirm that the authors were referring to the past tentative identification of the Hyksos with the Hebrews? If not, to whom are they referring?

wbhart··on Commander X16 8 bit computer now has its own website
Sure. It's just nice to know what the limitations are in that regard. Some demos for the Atari 8 bit machines for example did use them that way by lowering the resolution sufficiently far and then writing really tight assembly language. So I was just interested in comparing on that basis.
wbhart··on Commander X16 8 bit computer now has its own website
What I'm really curious to know is at what effective screen resolution it will have sufficient power to update every pixel on the screen in a single frame (assuming you are using assembly language and true graphics, not a character mode), with enough CPU cycles left over to do some computation.
wbhart··on How is NSA breaking so much crypto? (2015)
Harvey-van der Hoeven. And yes it is. But this is an asymptotic cost meaning you have to have absolutely enormous integers before the cost will be lower than the old algorithm. In fact, the crossover is so large it is quite possibly out of the range of anything we'll practically ever compute.

In particular, crypto typically works with integers zillions of times smaller, so you certainly don't want the Harvey-van der Hoeven algorithm for that.

wbhart··on Julia as a CLI Calculator
SageMath takes 3s to load for me (sometimes a lot more if my systems administrator has updated it recently, which seems to happen a lot).

I therefore use Pari/GP for my personal choice. I like the symbolic nature of Pari/GP over Sage or Julia, even though I spend nearly all of my life programming in Julia, and love the language a lot.

However, for computations of trivial things that I want to run really fast, I put them in a function in Julia (so that they are jit-compiled), since nothing will come close to that, by some orders of magnitude.

wbhart··on Autism severity can change substantially during early childhood, study suggests
There is very likely not a reliable scientific guide to making and keeping friends, because it depends very much on the circumstances and the people involved.

Some people have many shallow friendships, others just a few deep ones.

Some people extend the hand of friendship early, others take years of persistence to become friends with.

Some people value time spent together on shared experiences, others value talking, others value gifts or help in times of crisis and others value being told how good a friend they are (once the friendship is clearly there).

Many people are friends with individuals they have known since high school and it is generally harder to make new friends after that point. It's also pretty easy to lose friends as you age due to differences of opinions or beliefs.

Perhaps the biggest skills in making and retaining friends is finding common activities and experiences you can share with them (outings, games, sport, dining, interests, topics of discussion, etc.) and finding the right time to invite them to engage with you in such things.

Very often there are logistical hurdles to overcome and that is all: do they have a car, is there a convenient bus, is the venue you are meeting nearby, are you available when they are, do they have a babysitter, is the suggested date suitable for them, have they currently got some other crisis or deadline to deal with, etc.

I find that if I ask to spend time with people too often, they may think I am "clingy" or "needy" and push me away. If I ask too little, the friendship never really gets established. It's a balance that is different for everyone.

wbhart··on To software engineers criticizing Neil Ferguson’s epidemics simulation code
The problem is, unsophisticated models do not predict anything. You apply them in one country and they do ok, and apply them in another and they get it totally and completely wrong.

Unless all important factors are accounted for, they are going to result in incorrect information for someone. Public policy will then be based on incorrect predictions. People will grow tired of the predictions being wrong and they'll give up on data science entirely.

It's already quite bad that people think they can choose their reality by finding numbers that agree with them and ignoring the ones that don't.

I do understand the point you are making, which is like the epicycles argument. But in global warming and epidemics alike, more parameters are actually needed to model reality.

I do agree that those parameters should be based on actual data, not guesses though. But what value of R would you pick? Is that actually well-constrained?

wbhart··on Ask HN: Is YouTube Working Properly?
It's definitely down here where I live (Germany).
wbhart··on Five-year-old boy stopped on highway driving from Utah to California
Given that it took me a year to learn to drive, I wondered how he managed it. I had realised that given he wanted to buy a Lambo, he obviously loved cars. But eventually I realised it was probably an automatic not a manual transmission. It's still impressive that a 5 y.o. could manage to navigate that. I wonder if he was using turn signals and stopping at intersections and traffic lights.
wbhart··on How the Anti-Vaccine Community Is Responding to Covid-19
This was an interesting read. The style of presentation is quite unique. The overall tone of the article is in favour of vaccination, but it nevertheless provides many exact quotes of antivaxxers and other conspiracy theorists, usually without trying to directly refute what they say.

It's also well investigated, in the sense that caveats to the usual responses to antivaxxers are included.

I personally felt like I came away with a better understanding of what the conspiracy theorists are actually thinking/claiming. I learned some interesting facts about various vaccination campaigns, and overall felt like I came away with more information than I came to the article with.

I'm interested to see where this style of journalism leads.

wbhart··on Gilead data suggests coronavirus patients are responding to treatment
True, but that could be a single cherry-picked example just for the article. It does sound like the typical case might not be too far off that though, which is potentially very good news.
wbhart··on Six Months with Julia: Parse-Time Transpilation in 80 Lines or Less
There's a fairly sophisticated transpiler from a computer algebra system language called Singular, to Julia, here:

https://github.com/tthsqe12/SingularInterpreter/

It's still being developed, but Basically Works TM.

It does give some speedups over the original interpreter for the language, which has been in use for about 30 years:

https://github.com/tthsqe12/SingularInterpreter/blob/master/...

wbhart··on Adjusted Age-Specific Case Fatality Ratio During for COVID-19 in Hubei [pdf]
"We are all gonna die" is a statement about the mortality rate, not the case fatality rate. This paper does not deal with the mortality rate.
wbhart··on Adjusted Age-Specific Case Fatality Ratio During for COVID-19 in Hubei [pdf]
If I am reading it correctly, that is not what the paper says. It says that it takes into account the individuals who had the disease but were not reported/recorded.

Further to that, some individuals are asymptomatic which means that not only are they not reported, but they never are. They don't get the disease. It has nothing to do with how far the disease progressed in them, because they never have it.

wbhart··on Adjusted Age-Specific Case Fatality Ratio During for COVID-19 in Hubei [pdf]
It's worth pointing out that this is the CFR for the virus, SARS-CoV-2 (i.e. including asymptomatic individuals). The CFR for the disease, COVID-19, is 3.3% (2.9-3.8%).

I'm not sure which it is more common to report, but the 2% estimate that was used earlier in the epidemic was for the disease rather than the virus, apparently.

wbhart··on WHO Director: "Covid-19 does not transmit as efficiently as influenza"
It's clear the WHO message is trying to present the bad news in the best possible light. The sentences about transmissibility are very obviously constructed extremely carefully. However, I do take away from the report that Governments should get serious about containing this, because the experience of China shows that this is possible, whereas with the flu it's known to be impossible.

I think that is the right message at the moment. Simply acquiescing to some undetermined percentage of the elderly and random people of all ages dying is not a good strategy, and I think that is what he is trying to communicate.

wbhart··on Musicians algorithmically generate melodies, release them to public domain
Isn't it still a derived work though? (Serious question, not rhetorical.)
wbhart··on Musicians algorithmically generate melodies, release them to public domain
Release after a certain number of years is one possible way forward. The problem I see with that though is you want as much excitement as possible about your number one hit in the first few years. Covers, adaptions, arrangements, performances all add to the excitement around the thing you are trying to sell. You should want those.

My personal (not very practical) opinion on it is that any derived work that is musically distinct should be considered a separate work. If it isn't the same tune, it isn't the same tune, even if it is similar. If it isn't the same performance, it isn't the same performance.

In fact, the only thing that should be copyrightable by a composer is a specific arrangement of a melody, not the underlying melody itself. (The problem of course is that this is subjective, and not something the law or technology is well-equipped to decide.)

As for record companies, all they should care about is people ripping off their exact CD's and putting them on YouTube for free and not paying them. In my opinion, it's greed to want a cut of a performance/arrangement/cover of a melody that someone else put all the work into.

wbhart··on Musicians algorithmically generate melodies, release them to public domain
I don't think this is going to put a dent in cases of existing copyright holders making claims against people coming up with similar sounding works.

Firstly, there's an enormous corpus of music out there that precedes this effort, and those copyright holders can still make claims.

Secondly, and perhaps more importantly, how would someone prove that a musician copied the work from this algorithmically generated collection? These haven't been number one hits or in widely available collections. Someone could not conceivably argue that a musician derived their work from this due to familiarity with the melody.

I wish the copyright problem would go away. But I really don't see this as a solution.

A large number of musicians and software designers need to collaborate on a project that is much more permissive with regard to sampling, covers, arrangements, adaptions, etc, all the while preserving the rights of songwriters who just happen to write a number one hit song to get paid for their work.

The whole thing needs to be lucrative enough that composers, performers and the tech companies involved can afford to flip the middle finger to anyone exhibiting corporate greed.

wbhart··on Does memory leak? (1995)
Right, but that isn't the argument that was being used here, which is my point. The way I read it, the contractor cared only enough to get the design over the line so the customer would sign off on it. Their argument was that you shouldn't care about leaks due to scheduled deconstruction, not because of a technical consideration.

There exist options between no reclaim and using a garbage collector which could be considered, depending on the exact technical specifications of the hardware it was running on and the era in which it happened.

But retrofitting technical reasoning about why this may have been done is superfluous. The contractor already said why they did it, and the subtext of the original post is that it was flippant and hilarious.

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