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lkozma

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http://www.Lkozma.net

lkozma@gmail.com

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www.youtube.com 4y ago

Finnish man blows up his Tesla Model S with 30kg dynamite

lkozma
10pts0
www.reuters.com 4y ago

The Afghan minister who became a bicycle courier in Germany

lkozma
3pts0
www.curbed.com 5y ago

Artist Posed as Billionaire Buyer to Get into New York Penthouses

lkozma
1pts0
www.lkozma.net 5y ago

Useful Inequalities Cheat Sheet

lkozma
21pts2
lkozma.net 7y ago

A dual view of sorting algorithms

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2pts0
lkozma.net 11y ago

Show HN: Recursi - a fractal memory puzzle

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3pts0
lkozma.net 11y ago

Show HN: Recursi – a recursive memory/logic puzzle

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5pts0
gowers.wordpress.com 12y ago

Timothy Gowers: What I did in my summer holidays

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1pts0
lkozma.net 12y ago

Nonlinear speedometer

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2pts0
lkozma.net 12y ago

Visualizing the languages of the world

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2pts0
rjlipton.wordpress.com 14y ago

Mihai Patrascu, pathbreaking CS researcher passed away at 29

lkozma
3pts0
www.newyorker.com 14y ago

Missions Impossible: The Joy of Ridiculously Difficult Video Games

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2pts0
www.cs.virginia.edu 14y ago

Douglas Hofstadter's satire on sexist language [1985]

lkozma
3pts0
lkozma.net 15y ago

Show HN: Random wiki image as wallpaper

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3pts1
lkozma.net 15y ago

Web app ideas

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92pts18
www.lkozma.net 15y ago

Show HN: inequalities cheat sheet

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1pts0
www.youtube.com 15y ago

Timelapse video of a summer and a winter day in Finland

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2pts0
news.ycombinator.com 15y ago

Ask PG: Which are the oldest, still active user accounts on HN?

lkozma
1pts4
www.supermemo.com 15y ago

Good sleep, good learning, good life

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www.edge.org 15y ago

Gell-Mann on Feynman

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12pts1
www.math.rutgers.edu 15y ago

Doron Zeilberger on computer-assisted proofs

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27pts6
lkozma.net 15y ago

Ten random ideas

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2pts1
lkozma.net 15y ago

Shannon's juggling theorem

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news.ycombinator.com 15y ago

Tell HN: Starting a search startup, please review our project

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49pts35
lkozma.net 15y ago

Sketching data structures

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4pts0
www.schneier.com 15y ago

"If you aren't doing anything wrong, what do you have to hide?" [2006]

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2pts0
scottaaronson.com 15y ago

Scott Aaronson adds $200K to prize money if P≠NP proof correct

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56pts22
stackoverflow.com 15y ago

Alan Kay: Significant new inventions in computing since 1980?

lkozma
12pts0
news.ycombinator.com 15y ago

Ask HN: What are the biggest (simple) ideas in recent history of computing?

lkozma
2pts2
www.psychologytoday.com 15y ago

The grandmaster experiment

lkozma
3pts0

May I add one that I made?

Illustration of QuickSort and MergeSort as two sides of the same coin: http://lkozma.net/images/sort/duality.pdf

I find this somehow both obvious and counter-intuitive, and usually the two algorithms are not presented in this way, as duals of each other.

I wrote up this view in more detail, but the figure above should be self-explanatory: http://lkozma.net/blog/a-dual-view-of-sorting-algorithms/

"Seeing an astronomer using a telescope to observe a galaxy, no-one will confuse the telescope with the galaxy. Mathematics differs from science in that there is no clear distinction between the tools and the objects of study." -- D.Aldous

Your first point is correct, but just to clarify your second point, these two definitions are not quite equivalent, as there is a world of functions growing more quickly than log^k(n) no matter how large constant k, but still within n^o(1).

For an example, consider 2^sqrt(log(n)).

This is a bit similar to something being faster than polynomial, but slower than exponential.

Who is pushing/lobbying for that type of legislation? Isn't it a case of regulation helping the incumbents?

For those coming from a CS background a possible (crude) intuition sometimes given is that

frequentist :: Bayesian ~ worst-case analysis :: average-case analysis

There are a good reasons why we don't usually do average-case analysis of algorithms, chief among them that we have no idea how inputs are distributed (another reason is computational difficulty). Worst-case bounds are pessimistic, but they hold.

was posted here sometime ago:

The door refused to open. It said, "Five cents, please." He searched his pockets. No more coins; nothing. "I'll pay you tomorrow," he told the door. Again he tried the knob. Again it remained locked tight. "What I pay you," he informed it, "is in the nature of a gratuity; I don't have to pay you." "I think otherwise," the door said. "Look in the purchase contract you signed when you bought this conapt." In his desk drawer he found the contract; since signing it he had found it necessary to refer to the document many times. Sure enough; payment to his door for opening and shutting constituted a mandatory fee. Not a tip. "You discover I'm right," the door said. It sounded smug. From the drawer beside the sink Joe Chip got a stainless steel knife; with it he began systematically to unscrew the bolt assembly of his apt's money-gulping door. "I'll sue you," the door said as the first screw fell out. Joe Chip said, "I've never been sued by a door. But I guess I can live through it."

(Philip K. Dick: Ubik)

The Soviets royally sucked in the computation department

To add more nuance, there is an essay [1] telling the history of early maximum flow algorithms and includes this small anecdote:

[An] American asked: ".. how were you able to perform such an enormous amount of computing with your weak computers" to which the Russian responded: "we used better algorithms".

There is some truth to that, besides maximum flow, similar stories can be told about linear programming, data structures (e.g. AVL-trees), numerical computing, etc. The hardware may have been sloppy, but the algorithms-research was top notch.

[1] http://www.cs.bgu.ac.il/~dinitz/Papers/Dinitz_alg.pdf

However, you're being "too smart for your own good" if you go down this route. A perfectly unbiased input would still have 50% of its inputs rejected, and already you've dropped the speed of the RNG by 50%.

To improve this situation you can use an additional trick: keep track of the sequence of thrown-away pairs, and look at them again in consecutive pairs, and generate some more random bits:

* 00 00 -- throw away

* 11 11 -- throw away

* 00 11 -- output 1

* 11 00 -- output 0

and so on..

see the paper "Iterating Von Neumann's Procedure for Extracting Random Bits" for details.

That's true, but "high school algebra" in some countries also includes some group/ring theory basics (or it used to).

Vivaldi 4.0 5 years ago

One small thing in the latest redesign: if you have two tabs, one active, one not, the visual cues suggest exactly the opposite. The active one seems like a clickable button, the inactive one seems pushed down and not clickable.

After misclicking hundreds of times, I still couldn't train myself to go against my perception and follow the designer's "bold vision", using it feels like writing with my left hand or steering a bicycle with a crooked wheel.

This seems like a very accurate description, especially the observation about temporal continuity, which we take for granted, but on occasions it can feel like a fragile illusion.

Relatedly, there was an unintentionally funny translation of Gmail in Hungarian, where it was supposed to say "You have no conversations in Trash", or something like that. The translation was technically correct, but it sounded very much like "No more talking in the trashcan!", which was hard to read without imagining someone shouting at a trashcan with a person inside it.

This is a valid criticism from a practitioner point of view. From someone doing research in algorithms and data structures or someone just curious about it at an intellectual level, there is a different criticism:

All this focus on algorithms for the sake of interview-preparation gives the false impression that the field is a closed body of work. In reality it is an active and lively field of research with many (even most) basic questions not yet understood.

Someone could go through these 500 questions and for (almost) all of them formulate variants/extensions that would be open research questions. So instead of memorizing them, ask for each: Is this the best possible solution? Can I prove it? What if I restrict what the algorithm can do? What if I give the algorithm extra powers? What if the data comes online? What if the input is noisy? What if I want to optimize space usage instead of time? Is there a trade-off between the two? Etc. etc.

And related to the parent question: does the problem model a real practical problem? Why not? Can the model be changed to be more realistic?

All that being said, at a first look, the list seems like a quite nice collection of techniques.