Hacker Newsnew | past | comments | ask | show | jobs | submit | kurlberg's commentslogin

"Learning styles" might be a myth. Eg, see

Learning Styles: VAK Doesn't Exist (Here's What Research Actually Shows)

https://www.structural-learning.com/post/learning-styles-myt...

Belief in Learning Styles Myth May Be Detrimental (by American Psychological Association)

https://www.apa.org/news/press/releases/2019/05/learning-sty...


There is a joke saying "a mathematician says X, writes Y on the board and means Z". The really amusing(?) thing is that other mathematicians still (sort of) perfectly understands Z. Once you have enough experience you fill in the blanks automatically.

Math exposition is tricky: too few details and you're just floating in the sky, too many details and the audience loses sight of the forest for all the trees. You can go (more or less) all formal, but it's a pain for the writer and a pain for the experienced reader.

If it's any consolation, the punchline to the joke is that it often is small/big lie: the other mathematicians reads "Y" and goes WTF!? And then 1 minute, 1 hour, 1 day, or one week later says "aaah, that's what he/she meant! I guess it was 'obvious' all along". :-)


Even Terry Tao struggled at times: "When I was a graduate student in Princeton, Tom Wolff came and gave a course on recent progress on the restriction and Kakeya conjectures, starting from the breakthrough work of Jean Bourgain in a now famous 1991 paper in Geom. Func. Anal.. I struggled with that paper for many months; it was by far the most difficult paper I had to read as a graduate student, as Jean would focus on the most essential components of an argument, treating more secondary details (such as rigorously formalising the uncertainty principle) in very brief sentences."

More details at

https://terrytao.wordpress.com/2018/12/29/jean-bourgain/

(In particular, see the "???" in the Tao's annotated copy of Bourgain's paper.)


There is a cute argument (I think it is due to Erdos) that, asymptotically, 0% of the integers in [0,n^2] appears in the "n by n multiplication table":

By Erdos-Kac, almost all integers of size about n^2 have about log(log(n^2)) ~ log(log(n)) prime factors. However, almost all integers in the multiplication table have about 2*log(log(n)) prime factors.

Kevin Ford gets much more precise asymptotic estimates.


They address this argument in the blog.


Where?


I had the same impulse (or at least copy.fail inducing many to upgrade at the same time.) However, it might be a "pro-Iran hacktivist group" according to

https://www.theregister.com/2026/05/01/canonical_confirms_ub...

"Canonical says its web infrastructure is under attack after a pro-Iran hacktivist group instructed its members to target the open source giant."

Perhaps more to do with extortion rather than activism. (I have no idea how accurate theregister is on this story.)


Convolution alone does not smooth. Eg consider a random variable supported on the pts 0 and 1 (delta masses at 2 pts.) No matter how many convolutions you do, you still have support on integers - not smooth at all. You need appropriate rescaling for a gaussian.

Also, convolving a distribution with itself is NOT a linear operation, hence cannot be described by a matrix multiplication with a fixed matrix.


You are absolutely right. Even edge detection can be written as a convolution. That's why I mention averaging.

I address scaling, very peripherally, towards the end. Of course, depending on how you scale you end up with distinctly different limit laws.


Read it as a young teenager, can recommend.


This has been discussed on HN some times before. User xornot looked at the zfs source code and debunked "faulty ram corrupts more and more on scrub", for more details see https://news.ycombinator.com/item?id=14207520


I don't think this is entirely due to Wozniak. Early "home" computer systems were based on connecting cards to a bus (eg the S-100 bus), eg. with one card supporting the CPU, another RAM, a third for disk drive, video card etc, etc. The cards where then memory mapped, presumably you controlled the memory mapping by setting jumpers. (I guess you're saying that Apple II managed this automatically?) Of course the full story might be a bit more complicated: 6502 and 6800 used memory mapped I/O, whereas 8080 (and Z80?) had certain I/O pins coming out of the CPU.


Memory mapping happened automatically. Each card was mapped based on the slot it was in. $C000 - $C700 I believe with each slot assigned 256 bytes.


You're correct; slot 6 for instance is $C600. If you crashed to the system monitor you could boot a disk by entering C600G (with the 'G' standing for 'go to').

IIRC the disk controller had firmware that loaded the first 256 byte sector from disk into memory.


If you crashed to the monitor, you could hit Ctrl+B and get back to BASIC, then type IN#6 to boot the disk.


Yeah. It was neat. But it rebooted in under a second so a complete crash was no biggie.

RAM wasn't even cleared so usually no (or limited) data loss.

I thought it was PR#6 (redirect output) to boot from the disk controller in slot 6. I wonder what redirecting input would do.


That was it at the AppleSoft BASIC prompt (or IN#6). But the parent poster commented on how to do it from assembly.


There is an even quicker way from the monitor:

6 CTRL+P

Will instantly divert output to slot 6. (and boot the disk if there is hardware there)


Both worked to start a boot from the disk controller in that slot.


Fun historical fact: knot theory got a big boost when lord Kelvin (yeah, that one) proposed understanding atoms by thinking of them as "knotted vortices in the ether".


If you have a child who likes math I highly recommend "Really Big Numbers" by Richard Schwarz. Tons of nice illustrations on how to "take bigger and bigger steps".

"Infinity is farther away than you thought."


Guidelines | FAQ | Lists | API | Security | Legal | Apply to YC | Contact

Search: