fyp

There's actually an entire branch of math (galois theory) that spawned from the fact that it doesn't generalize!

In particular, there's no formula for polynomials of degree 5 or higher.

https://en.wikipedia.org/wiki/Abel%E2%80%93Ruffini_theorem

Previous thread: https://news.ycombinator.com/item?id=21720656

There are a lot of similar failure modes in humans.

Sometimes they're are used for good, like making drivers slow down: https://www.insider.com/optical-illusions-3d-crosswalk-drivi...

But other times they cause crashes: https://imgur.com/a/kYr94

I don't know the details but I heard the original codebase was javascript but they used an automated script to convert it to coffeescript as an hack week project! That's some serious long term damage they did in that one week.

Edit: Found the 2012 post, pretty useful for doing a postmortem https://dropbox.tech/application/dropbox-dives-into-coffeesc...

Another similar project by Mark Rober for darts: https://www.youtube.com/watch?v=MHTizZ_XcUM

This is probably premature optimization, but what's the performance cost of updating a deeply nested field inside a jsonb? What about indexing it?

(compared to storing in some normalized form or in other popular document stores)

Uber/airbnb/lyft were considered in the same tier as facebook/google before corona. With google also slowing hiring, are the engineers laid off all going to be absorbed by facebook?

I have not read it myself but the answer can probably be found in the book "The Science of Interstellar" [1]

Kip Thorne, a Nobel prize-winning physicist, worked as the science advisor for Interstellar so the hollywood bs is pretty good!

[1]: https://www.amazon.com/Science-Interstellar-Kip-Thorne/dp/03...

Isn't that the wrong direction for the optimization? I would assume you would want to compile adding two numbers into shifting by one, not the other way around.

(I know nothing about hardware, it just intuitively seems like moving a bunch of bits over by 1 should be faster than dealing with xor and carries)

Even with worst-case scenario of bias, this is still extremely good news. My worry was always with super spreaders who refuse to isolate but the data is suggesting that those spreaders will still soon achieve herd immunity among themselves. As long as the rest of the society behaves we will still hit zero cases relatively quickly.

(which wasn't always clear to me before since I initially predicted that this will take years to work out)

Use a profile picture that's already public and have been crawled a bajillion times. E.g. https://twitter.com/jbverschoor/photo

Hmm is the argument that you can generate infinite money otherwise? I think the two directions only look superficially the same because externalities and labor isn't taken into account?

One of my colleagues loathes competitive programmers and picks much harder problems for them. His grumpy rationale is that they shouldn't have it any easier just because they do interview problems as a sport. Usually the ICPC world finalist types will still ace it since he's too dunning-kruger to judge beyond his own skill level.

Most algebraic structures are best understood by which axioms it satisfies. For example basically every subset of axioms of an abelian group is useful enough to have a name. Wiki has a really nice table:

Semigroupoid

Small Category

Groupoid

Magma

Quasigroup

Unital Magma

Loop

Semigroup

Inverse Semigroup

Monoid

Commutative monoid

Group

Abelian group

https://en.wikipedia.org/wiki/Abelian_group

Does anyone else think NY called their peak prematurely? It seems like there's some periodicity in the data and there's always a slight two day drop every 7 days. This makes sense since many people are still working mon-fri in the city.

This is for NYC specifically (last few days of data are incomplete): https://www1.nyc.gov/site/doh/covid/covid-19-data.page

I wouldn't be surprised if NY continued surging in the coming days.

An unexpected application of feistel network is for creating neural networks that are invertible!

https://arxiv.org/abs/1802.07088

To put this in perspective, NYC is projected to run out of ventilators early next week[1]. That means if you catch it now and need ICU, there's no medical equipment to save you.

Whether government mandated or not, people are gonna stay the fuck home because they don't want themselves or their parents to die in a hallway.

[1] https://www.nytimes.com/2020/04/02/nyregion/coronavirus-new-...

I lived on $200/month in SF (single person) and I definitely didn't "eat like an actual human being". But the problem was definitely me and not that it wasn't possible.

Usually in those financial conditions you also know your time is better spent elsewhere. An extra hour per day practicing for interviews is much better use of your time than cooking. So you do the most efficient thing possible, which is just throw whatever is cheapest per lb into a slow cooker and eat it for the rest of the week. Most stuff is pretty disgusting after a few days in the fridge.

It's probably possible do meal prep cheap/fast/delicious, but I definitely never learned how. Tips appreciated!

It's definitely not an unpopular opinion, especially on HN. Pre-corona I was probably a crazier privacy nut than most so I completely understand where you're coming from.

But right now our privacy is not worth more than our parents' and grandparents' lives. You ought to re-run your moral calculations with the current state of the world in mind. There are literally millions of lives at stake.

Also I am hoping for tech solutions that do preserve privacy to some degree. Singapore seems to have a decent solution where the user has to opt-in: https://www.businessinsider.com/singapore-coronavirus-app-tr...

Even if you focus on pure tech problems, startups seems to be failing us in the US.

Other countries have scaled out thermal imaging for fever detection, face tracking for contact tracing, and have mobile apps that can warn people where a previous infected patient have visited before. I have yet to see any of that here.

Your link is already a great resource, thanks for that! I didn't know Susan Fowler was a physics major at UPenn.

The tl;dr; seems to be get "University Physics with Modern Physics" and go from there?

In china, a lot the spread isn't from stranger to stranger but family to family:

https://www.bloomberg.com/news/articles/2020-02-28/coronavir...

https://youtu.be/e3gCbkeARbY?t=37

How do you do physical distancing within your home? Eat meals alone? Don't share cups/plates? Wear gloves for doorknobs? I feel like there's currently no solution for this.

The NY governor in your video cited that 40-60% of people are going to get it (20 min mark) and the same thing was said by CA governor a couple days ago too (56%): https://news.ycombinator.com/item?id=22633570

So it seems like there's a consensus within the top-level leadership that containment is impossible. I still don't understand why we've given up when China managed to do it.

Side question: How do you create the "paper" texture? Or is it just an image here?

Why did we give up on containment?

China and South Korea have shown that it's possible. China capped out at only 100k infected for a population of 1.4 billion.

Aiming to let 56% of your population get infected of which more than 3% will die is NOT the solution.

China's strategy seems simple enough. Close off borders of a region, stamp out all existing cases with aggressive testing, then keep the region at 0 cases by requiring mandatory 2 week quarantine before letting anyone in. Do this one region at a time until your country is all clean. Now their biggest problem is teaching the rest of the world this strategy.

Are companies really laying people off this early? It's still unclear what the exact economic impact on tech companies will be.

If they are stopping interviews, I bet it's just due to the social distancing requirements. Once they figure out remote interviews it will restart again.

It would be so useful if I got a notification if I happen to have crossed paths with a person who later turned out to be infected so I can get tested too. This will preempt so many asymptotic transmissions.

Such apps are already deployed in china: https://youtu.be/YfsdJGj3-jM?t=303

We don't trust the government but what if it's just a private company who does it? Google already has your location info: https://www.google.com/maps/timeline They are definitely already using the information in aggregate to provide traffic jam info. Hell I am sure facebook already does this for suggesting friends too. On the balance of privacy vs social good, I don't think there's even much slippery slope left to protect.

Confinement by itself is not enough. See Donald McNeil's interview on what china is doing: https://youtu.be/e3gCbkeARbY?t=32

If our testing infrastructure is in place to get correct counts, yes. Countries can be "graded" based on their trajectory on this graph:

https://ourworldindata.org/coronavirus#trajectories-since-th...

China has shown that it's possible to contain the virus even though they were initially criticized for it being "draconian".

They've capped out at under 100k cases (at least for the first wave) with 3k deaths: https://en.wikipedia.org/wiki/File:2020_coronavirus_patients...

Imagine if china had gone for the herd immunity strategy instead. With a population of 1.4billion and letting everyone get infected you are looking at 42 million deaths.

If draconian measures is what it takes, that is what the world should do.