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aoki

437 karma · joined June 22, 2016

http://www.paulaoki.com/
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aoki··on Ask HN: Recommend a maths book for a teenager?
The books by Tent are mathematically at a 4th or 5th grade level. They’re sort of like Jean Lee Latham’s bio of Nathaniel Bowditch (you learn a fictionalized life story but you can’t really grok the person’s contribution). Of course, most mathematicians lead far more boring lives than Bowditch did in his youth, so the kind of kid who is reading Harry Potter by 4th or 5th grade is going to find them very dry.
aoki··on 5G and Shannon’s Law
Ambitious wireless folks were already pitching MIMO mobile networks to investors. For example, ArrayComm was started in 1992.
aoki··on Google Culture War Escalates as Era of Transparency Wanes
you should try offering three peer bonuses
aoki··on Paris’ Problem with the Dead
There’s a relatively recent novel set during the removal of Les Innocents to the new catacombs (Pure, by Andrew Miller). A good read, and like many discussions of these events, it makes the obvious connection to the moribund Ancien Regime.
aoki··on Blackbird SR-71 Flight Manual (2010)
“battle short”
aoki··on Spinning a Yarn
The chapter in The Invention of Tradition (there are PDFs of the book online if you're interested in the topic) is about the efforts by Scottish nationalists over the century prior to the Allens to establish the idea of kilts and clan tartans (and efforts by historians against these ideas - the author of the chapter points to a 1940 book by McClintock as making the case "conclusively"). Clan tartans were not, as represented in the article, "all made up in 1829 by two brothers from Surrey" - the Allens were popularizers, not the origin of the idea.

I mention this because I think that the whole idea of political "invention of tradition," while it has lost currency because it seems to reflect poorly on anti-colonial nationalist movements, is far more interesting than that of "random people making up stories for gain."

aoki··on Spinning a Yarn
The bogosity of clan tartans has been documented since at least 1940; see the footnotes in the chapter on Highland culture in Hobsbawm and Ranger’s The Invention of Tradition (1983).
aoki··on Ask HN: How to self-study mathematics from the undergrad through graduate level?
alnar is likely referring to the US system, or something like it: unless you are tutored externally (rich), an autodidact outlier (gifted), or selected for honors courses, you basically take computational courses for 14 years (with one cursory stop for euclidean geometry) and are then thrown into proofs at the age of 19-20, if at all. it's widely recognized as a problem in the math pipeline, which is why many US universities have "transition" courses for non-honors students.

so it's not that the basics are intellectually difficult as much as practically difficult (unfamiliar, disorienting) for many students. many "transition" books talk about the difficulty in adjusting from talent being redefined from perfectionist "plug and chug" (APs, SATs) to reasoning and creativity.

btw, i'm impressed that you could master college-level proofs at 10. i have a kid about that age who is pretty good at logical reasoning, but i'm not sure what topic (at that level) he could do a rigorous proof about; maybe numbers, as in landau? can you say more about the materials you used?

aoki··on Ask HN: How to self-study mathematics from the undergrad through graduate level?
please consider the statement from the position of a student just learning the material (like the OP). if you are working through a book with 1000+ problems, like pinter (as some people are suggesting), and you have to keep looking up stuff like how to verify a subgroup, how long is that book going to take you?

to me, memorization means to recall the important parts of something accurately and precisely so that they can be used fluently. that is not to say textually (rote memorization). i do not think it is enough to say "well, that's what learning is" because i doubt most people learn most things to that level.

aoki··on Ask HN: How to self-study mathematics from the undergrad through graduate level?
i agree that memorization by internalization (concepts) is different from (and superior to) memorization by rote (text); i was agreeing with the other fellow that rote memorization is not the end goal. however, to me they're both "memorization" because they both represent work to achieve fluency in application.

however, i made my comment because i think i disagree that spaced repetition has no place in learning. i think that if you dig around in the Polar guy's earlier comments, you'll find threads where folks like michael nielsen are talking about using spaced repetition tools for much more than purely textual memorization of theorems - basically, cycles of repetition and (re)synthesis. so i don't feel it's right to completely shut him down about card decks. you may disagree, of course.

aoki··on Ask HN: How to self-study mathematics from the undergrad through graduate level?
very true, in the sense that rote memorization is not the point.

but false in the sense that doing math requires fluency - in applying a small amount of technique up to lower division math, and in applying a large number of definitions/results after that. in areas like abstract algebra, failing to memorize will kill you. it is as disfluent as writing text in a foreign language without having memorized the working vocabulary and grammar; even if you can eventually recall, derive or look up what you need, it's just not practical to work like that. (and i say this as someone who prefers to mentally index information rather than memorizing...)

aoki··on Ask HN: How to self-study mathematics from the undergrad through graduate level?
in the US, most engineers take the standard two-year lower division sequence (calculus, linear algebra, a bit of diffeqs). for the most part, you learn technique rather than proving things. upper division engineering math courses teach more technique (e.g., more diffeqs).

but as madhadron says, you can't read/write proofs of upper division or graduate level math without the "foundations" material, which includes naive set theory.

do you need any of that to do engineering math? well, there are a couple of standard quotes, relating to the fact that the technique taught is brittle, in weird and subtle ways. the claim is that understanding the proofs tells you what the limits of applicability are.

"[F]or more than 40 years I have claimed that if whether an airplane would fly or not depended on whether some function that arose in its design was Lebesgue but not Riemann integrable, then I would not fly in it." - richard hamming, "mathematics on a distant planet"

"It is customary to begin courses in mathematical engineering by explaining that the lecturer would never trust his life to an aeroplane whose behaviour depended on properties of the Lebesgue integral. It might, perhaps, be just as foolhardy to fly in an aeroplane designed by an engineer who believed that cookbook application of the Laplace transform revealed all that was to be known about its stability." - tom korner, fourier analysis

aoki··on Using spaced repetition systems to see through a piece of mathematics
in case anybody's curious, the Einstein letter mentioned in the article is Appendix II of Hadamard's "The Psychology of Invention in the Mathematical Field" (ISBN 0486201074).
aoki··on Norwegian frigate sinking has far-reaching implications
the general idea is that it is unhealthy to be right in the beam of a high-power air search radar. when you are in port, you get used to lots of pierside announcements to the effect of "do not rotate or radiate any electrical or electronic equipment while men are working aloft [in the masts of a ship at this pier]."

on most ships, the air search radars are on masts or platforms well above where any people work while underway. but on US AEGIS ships (CG 47, DDG 51), the pilothouse is located above the phased array panels. however, all of the arrays are on the outside of the blocky superstructure, pointing AWAY from the pilothouse. (there was a quote in that message about not leaning over the rails when standing on the bridge wings!)

the navantia design and derivatives (including the Nansens) did not take up this idea. presumably because they're smaller and needed the stability, but i'm just guessing there.

aoki··on Norwegian frigate sinking has far-reaching implications
You can’t, in general, put people above the air search radar. (Exercise for the reader: why is it ok for the pilothouse of US AEGIS ships to be located above the SPY-1 arrays?)
aoki··on Norwegian frigate sinking has far-reaching implications
The 70s era DD I served on had a fully enclosed pilothouse. Everybody standing underway deck watch (except the deck sailors standing lookout watch on the bridge wings and aft, and the signalmen in the signal shack above) was in the pilothouse.
aoki··on Norwegian frigate sinking has far-reaching implications
The DLGNs were reclassified as CGNs in the 70s. As you say, they were decommed after the Gulf War (after spending all that money on NTU).
aoki··on The story behind Turkish Delight
As a kid growing up in the US, I liked “Aplets and Cotlets” a lot, so I could really empathize with Edmund. I suppose that if my parents had given us rose or bergamot lokum it would have been a very different story.
aoki··on Simple proofs of great theorems
It seems to me that most commenters are missing the point, which is that results like these usually remain unproven until the end of 2-3 course sequences that are mainly taken by math majors. What the authors are doing is to reduce each result to something that can be verified by a high school calculus student (even if it does not provide very much insight). These are not elegantly concise proofs; they are maximally elementary proofs that you can give to a curious kid. I think there’s value in that, even if that’s not what mathematicians do with their proofs.
aoki··on Leslie Lamport Tells Mathematicians How to Write Proofs (2014)
mathematicians writing for peers don’t aim for the maximally explicit proof. details are frequently left out as obvious to the knowledgeable reader. leaving out tedious matter is a matter of professional style, like tightening regular prose so it doesn’t club the reader over the head with every detail. (my instructor in Fourier analysis would subtly grimace at my very explicit proofs in office hours, but he knew i was a computer scientist so he politely said nothing because he knew it would do no good ;-)
aoki··on The coming corpus-based reexamination of the Second Amendment
it was interesting to see from the comments that there have already been corpus analyses filed as SC amicus briefs (not just law review papers).
aoki··on GDPR
for anybody who didn't attend high school in the USA: https://en.wikipedia.org/wiki/Quartering_Acts
aoki··on Manipulating the Alpha Level Cannot Cure Significance Testing
NHST was always intended to provide evidence within a corpus of replicated research. institutionalized careerism creates disincentives for science to work that way in practice.

it's actually consistent with the NHST paradigm to treat any given result with skepticism; the degree of skepticism depends on many things, some of which are statistical and some of which are domain-specific. but skepticism is not the same as assuming invalidity. imperfect experiments are still (expensive) evidence for something.

imo, what you should reject entirely are media reports (usually based on somebody's PR team) that try to tell you to do anything based on one study or the work of a single lab.

aoki··on The Social Network Employers Love to Raid
i don't think it's as inaccurate as you're suggesting, though.

i've recently taken upper-division/graduate courses in math, stats, EE and CS at three different US universities. 100% of the courses used piazza, because professors and TAs don't want to pollute their inboxes with questions and most questions end up being answered by students. it's not great, but it supports latex math (!) and its discussion features are much better than canvas (which tends to be the default, officially-blessed system these days).

membership in courses (and hence institutions) is usually managed by the instructors based on university email. "social network" features are pretty basic (based on courses, institutions, and contacts) but definitely exist.

i imagine the main draw for employers is that it's a nearly universal pool (for certain majors) of opted-in university leads with relatively reliable major/institution/coursework data for filtering.

"raid" might not be the best word choice, but given that students "have to" sign up to get course help and will probably manage to click on the opt-in careers button at some point, i can kind of see how people can see this pivot as skeevy.

aoki··on Motorola M68000 Family Programmer’s Reference Manual (1992) [pdf]
mine as well (albeit 4th edition, 1984). which is sort of weird because i never saw or touched an M68k HP; i only ever referred to it when debugging stripped binaries on Sun 3s.
aoki··on Does Clean Laundry Have Germs?
you see news articles about norovirus all the time in the context of cruise ships because these are enclosed spaces with stable populations who infect and re-infect each other through fecal contamination and aerosolized vomitus. full decontamination (to stop the spread) without clearing everyone off the ship is very difficult.

imagine a house with small children (who are not good at personal hygiene) as a tiny cruise ship which you can never fully disembark, and then when the cooking/cleaning staff (parents) get sick, things get really ugly.

it's generally easier to clean the hard surfaces in your house (with harsh stuff like bleach wipes) than to clean the soft surfaces. that's presumably why she focuses on the laundry infection vector.

aoki··on Does Clean Laundry Have Germs?
agreed. i really enjoyed the fact that she (as a phd in biochem) orients to many of these tests as experiments. in her test of the SteriPen, she tries water samples with varying levels of turbidity (the SteriPen is based on UV) rather than just trying one thing and declaring "woo! it works!" (which is all you'd really expect from a product review blog).
aoki··on Tech Industry Really Needs Professors and Teaching Talent
anecdata from the current hiring season is that CS hiring at less prestigious institutions has become qualitatively different from that in other fields. one faculty described receiving a total of four applications from actual CS PhDs (not just top five) [0].

even at stanford, perhaps. i was astonished to see that a stanford junior is the listed instructor for EE 364A (a PhD level course in convex optimization, aka CS 334).

[0] https://news.ycombinator.com/item?id=16482866

aoki··on The Last Days of the Blue-Blood Harvest
yet in practice overfishing occurs in species after species; individual interests do not always align with the macro interests.

that's why i think there's an interesting story lurking here. there were probably a small number of technocratic players involved (maybe even one) who were able to specify how the chain should work.

aoki··on Shortwave Trading: The West Chicago Tower Mystery
i am not sure i would agree that this has been discussed before. this is not simply about use of RF (microwave, mmwave) for HFT. as i understand it, that kind of thing typically involves COTS radios and conventional dish antennas.

this instance appears to involve longer-range links and SDRs (in this case, the ettus USRPs).

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