comnetxr

n^n^n^n^n^n is an upper bound for general n, but the special case of only 2 people can be done with just 1 query.

the algorithm is just to have person A cut into two equal slices and then person B choose their favorite slice. it takes just 1 second, which is quite a speedup over the upper bound...

Yep, this is it. The key is not that there are two time dimensions but two independent time translation symmetries, each which translates the system by a different period of time corresponding to the two frequencies in their pulse. The two time dimensions is an analogy that’s useful for the theoretical treatment of such a system.

does anyone know if you could take a window and make it always be in the background -- the reverse of "always on top", say "always on bottom"? doesn't seem to be an option on Mac or in Gnome that I can tell but maybe there is someway to gain that functionality.

looks great. wish I could break it free from the browser though. a browser tab can't really be the backdrop to my work, and clicking into a browser tab just to view the visualization is an extra distraction -- defeating the purpose. Doesn't seem realistic, but I wish I could set this to be my desktop background without loosing the interactivity.

My understanding is that this project is more of a way for established researchers in a very theoretical field to start thinking about climate while using their existing skill sets to contribute.

In the long term, if we eventually make it to the scenario where we stop putting CO2 into the atmosphere on net, then each kg of CO2 input into the atmosphere must be compensated by a kg of CO2 removed by some mechanism or another. The reasonable thing to do in that equilibrium would be to set the price to output CO2 - collected by governments as a carbon fee - equal to the price to capture CO2, paid out by governments as a negative carbon reward. Of course we could just do that now, the trick is how to get to that equilibrium scenario without collapsing the economy in the process.

Is this AI generated text? It doesn't provide any context a normal human would want. The attempt at providing context feels exactly like an AI searched a database of summaries of research for something related.

how do you know the passionate to the point of addiction Yang supporters are real?

I think its likely that many are, but that there are also many passionate supporters of the other candidates who just lurk on Twitter without posting due to social norms about how often you should chime in and how forcefully. The social norms around Yang supporters on twitter have changed by bots posting often and loudly, breaking the bubble and giving permission to people to do it too. If you then turn the bots off, the YangGang effect would last. (I'm sure this applies to not just Yang...)

Someone should make a Twitter-like that verifies posters at various levels based on humanness/geographic locale and other characteristics.

Then posters could limit conversations to those with >90% human score (with score going up when twitter has more certainty that you are a human) located in the US (for US political conversations), etc.

I'd certainly pay a few bucks to be verified and contribute much more often to conversations than I do now, as now it just seems like screaming into the bot void.

There seems to be a lot of confusion here about the complexity, for example calling the simulation here "in the linear regime" due to IBMs result. This is inaccurate.

A source of this confusion is that we need to discuss space and time complexity simultaneously. In the algorithms for quantum simulation (and many other algorithms), there is a trade off between space complexity and time complexity. ELI5: You don't have to store intermediate results if you can recompute them when you need them, but you may end up recomputing them a huge number of times.

For the quantum circuit, the standard method of computation gives exponential memory complexity in number of qubits (store 2^N amplitudes for a N qubit wavefunction) and time complexity D2^N, i.e. linear in circuit depth and exponential in number of qubits. For example, under the IBM calculation, 53 qubits at depth 30 use 64 PB of storage and a few days of calculation time, while 54 qubits use 128 PB and a week in calculation time. Adding a qubit doubles the storage requirements AND the time requirements.

Under google's estimation of the run time, they were using a space time memory tradeoff. There is a continuous range of space-time memory tradeoffs - USE MAX MEMORY as IBM does, MAX RECOMPUTATION (store almost no intermediate results, just add each contribution to the final answer and recompute everything) and a range of in-between strategies. While I don't know the precise complexities, the time-heavy strategies will have time complexity exponential in both N and D ( 2^(ND) ) and space complexity constant.That's why googles estimate for time complexity is so drastically different than IBMs.

Side note: IBM also uses a non-standard evaluation order for the quantum circulation, which utilizes a trade-off between depth and number of qubits. In the regime of a large number of qubits, but a relatively small depth, you can again classically simulate using an algorithm that scales N*2^D rather than D2^N, using a method that turns the quantum circuit on its side and contracts the tensors that way. In the regime of N comparable to D, the optimal tensor contraction corresponds to neither running the circuit the usual way or sideways but something in between. None of these tricks fundamentally change the ultimate exponential scaling, however.

As an extra step, you could also run compression techniques on the tensors (i.e. SVD, throwing away small singular values), to make the space-time complexity tradeoff into a three-way space-time-accuracy tradeoff. You wouldn't expect too much gain by compression, and your accuracy would quickly go to zero if you tried to do more and more qubits or longer depth circuits with constant space and time requirements. However, the _real_ quantum computer (as Google has it now, with no error correction) also has accuracy that goes to zero with larger depth and number of qubits. Thus, one can imagine that the next steps in this battle are as following: If we say that Google's computer has not at this moment beaten classical computers with 128PB of memory to work with, then google will respond with a bigger and more accurate machine that will again claim to beat all classical computers. Then IBM will add in compression for the accuracy tradeoff and perhaps again will still beat the quantum machine.

So this back and forth can continue for a while - but the classical computers are ultimately fighting a losing battle, and the quantum machine will triumph in the end, as exponentials are a bitch.

No. I think this is where your logic is off: "Furthermore, I think that if I try to read an entangled state, it's as if I am reading the entire state all at once"

You can't read the entire state. A quantum channel where you send n-bits lets you read n-bits, not exponential in n-bits.

There is indeed reduction of signal as you increase temperature. Under the error correction theorem, you can amplify that signal back to full strength as long as you are under a threshold temperature (but with ever-increasing resources as you approach the threshold temperature.)

Also this: "This is going to generate heat, and the rate at which I can dissipate that heat is bounded by the speed of light". Sure, the heat has to be transferred out of the system, which takes time that is bounded by some distance divided by the speed of light. But the qubit is on a 2D chip surrounded by a 3D refrigerator. The distance doesn't necessarily increase with increasing qubits.

There seems to be a lot of confusion here about the complexity, for example calling the simulation here "in the linear regime" due to IBMs result. This is inaccurate.

A source of this confusion is that we need to discuss space and time complexity simultaneously. In the algorithms for quantum simulation (and many other algorithms), there is a trade off between space complexity and time complexity. ELI5: You don't have to store intermediate results if you can recompute them when you need them, but you may end up recomputing them a huge number of times.

For the quantum circuit, the standard method of computation gives exponential memory complexity in number of qubits (store 2^N amplitudes for a N qubit wavefunction) and time complexity D2^N, i.e. linear in circuit depth and exponential in number of qubits. For example, under the IBM calculation, 53 qubits at depth 30 use 64 PB of storage and a few days of calculation time, while 54 qubits use 128 PB and a week in calculation time. Adding a qubit doubles the storage requirements AND the time requirements.

Under google's estimation of the run time, they were using a space time memory tradeoff. There is a continuous range of space-time memory tradeoffs - USE MAX MEMORY as IBM does, MAX RECOMPUTATION (store almost no intermediate results, just add each contribution to the final answer and recompute everything) and a range of in-between strategies. While I don't know the precise complexities, the time-heavy strategies will have time complexity exponential in both N and D ( 2^(ND) ) and space complexity constant.That's why googles estimate for time complexity is so drastically different than IBMs.

Side note: IBM also uses a non-standard evaluation order for the quantum circulation, which utilizes a trade-off between depth and number of qubits. In the regime of a large number of qubits, but a relatively small depth, you can again classically simulate using an algorithm that scales N*2^D rather than D2^N, using a method that turns the quantum circuit on its side and contracts the tensors that way. In the regime of N comparable to D, the optimal tensor contraction corresponds to neither running the circuit the usual way or sideways but something in between. None of these tricks fundamentally change the ultimate exponential scaling, however.

As an extra step, you could also run compression techniques on the tensors (i.e. SVD, throwing away small singular values), to make the space-time complexity tradeoff into a three-way space-time-accuracy tradeoff. You wouldn't expect too much gain by compression, and your accuracy would quickly go to zero if you tried to do more and more qubits or longer depth circuits with constant space and time requirements. However, the _real_ quantum computer (as Google has it now, with no error correction) also has accuracy that goes to zero with larger depth and number of qubits. Thus, one can imagine that the next steps in this battle are as following: If we say that Google's computer has not at this moment beaten classical computers with 128PB of memory to work with, then google will respond with a bigger and more accurate machine that will again claim to beat all classical computers. Then IBM will add in compression for the accuracy tradeoff and perhaps again will still beat the quantum machine.

So this back and forth can continue for a while - but the classical computers are ultimately fighting a losing battle, and the quantum machine will triumph in the end, as exponentials are a bitch.

The climate change argument for EVs is kind of weak, since you still have to produce the electricity

I also find this line of reasoning problematic. The climate change effect of EVs is _indirect_, but that doesn't mean it's _weak_. It a required step for a huge amount of emissions reductions. Climate change is hard precisely because the economy is full of network effects and path dependencies where you can argue against each individual change by saying that it doesn't do that much for the climate by itself (and for each change, there will be motivated actors making those arguments when the alternative will hit their pocketbooks).

The question should not be whether this is too costly as compared to jet fuel, but at what carbon price is it cheaper than jet fuel? Once the cost of carbon is at the long term limit, which is equal to the cost of extracting carbon from the atmosphere, then these technologies could be much more cost effective. (But if they aren't, there would be no reason to ban flying, as the carbon price would pay for the extraction of carbon that flying produces.)

By not account for how much jet fuel costs with increasing carbon pricing, and by framing the alternative to allowing climate change as banning flying, it seems like the author has completely missed the story..

I had an idea for a minimal change to improve a Reddit-like site, perhaps you will find it interesting: split the concept of "subreddit" into "tags" and "communities".

Tags: much of the content of Reddit is people reposting the same thing at various times to various subreddits, and many of the comments are people noticing that it fits into "r/whatever" instead. The default behavior should be that posts of the same link to various tags (r/awww, r/catsstandingup) should not recreate a new post but just backlink to the same post. Repeat posts to the same tag should be a no-operation. This removes the community aspect of tags, and some of the worst emergent behaviors of reddit along with it. Treating a tag as both a topic and a community leads to a neverending cycle of people creating niche topic tags for the community aspect, but then finding themselves "invaded" as people will always want to find and comment on content about topics that they disagree with.

But of course the community aspect of Reddit leads to good things. So you make a separate concept of communities. These communities could follow the posts of one or more tags, applying filters to those of their own choosing, and make their discussion visible within community borders only or visible to all, based on their own choices (in addition to internal community posts.) They can control admission to the communities on their own rules (fully public, invite codes only, etc.) The ability to automatically follow the posts of certain tags (and either view or not view public comments) will keep small communities from getting stale for lack of posts.

has anybody proved something interesting in Lean? Perhaps not too difficult, but some proposition that might take a couple of days of work done in hours? I'm all for encoding foundations in a programmatic framework, but it seems that the idea here is to make this a useful tool for practicing mathematicians. The documentation didn't seem to have any examples of how that might happen.

Imagine if grocery stores forced us to choose one of a few dozen grocery "insurance" memberships to buy groceries, and negotiated directly with the insurers. No prices are labeled in store, they just detect whatever you take and send you a bill at the end of the month. (Differing brands of the same food product are not available in store of course.) Individuals are charged 3-100x more per product than negotiated rates, but can't find out until afterwards. Grocery "insurance" would then become a necessity. People would trade away disproportionate amounts of their salary to get good grocery benefits from their employers, i.e. to not get price-gouged by virtue of being an individual on the market. Stores would run discount programs for the very poor, which they could point to when people get outraged (as drug companies do now.) When politicians would threaten the system, grocery stores would fund ads about the "long lines" and limited food availability that would occur. Instead laws would get passed reinforcing the system by making sure everyone gets grocery insurance, as its a necessity (and it would _be_ a necessity).

I'm not saying that health care _could_ be exactly like grocery stores, with many alternatives, transparent pricing, and customers making the final decisions, but that it would have to be much _more_ like grocery stores to call it a free market. What we are working with now is just a system of pricing cartels supported by fear and lobbying. It needs to go.

In a sense, wasn't the choice to not negotiate drug costs itself the result of a negotiation? I believe the way it works is that health insurers and providers threaten to fund fear-mongering attack ads against politicians who support laws that don't like. The politicians cave and carve out rules for the industry.

So it's not that the Medicare drug care costs aren't negotiated, its that the chance for lower costs was traded away by Congresspeople of the past (many of whom aren't in office anymore) in exchange for campaign funds. Not literally a campaign fund check, of course, but countering an attack ad costs campaign money that they could be spending otherwise.

What other goods is the US Gov the sole buyer of, for which the sellers can't easily shift to other customers? Cop cars clearly doesn't apply, as carmakers have other customers. Doctors, hospitals, and pharmaceuticals will face true monopsony, which means sell at gov rates or quit entirely. Some suppliers will quit entirely, but most won't.

Therefore the win here is that they have verified that a 50 qubit quantum computer "works" (success rate > 10^-3 > 0.) No classical computer could verify a 100 qubit quantum computer in the same way (but you could verify various 50 qubit subsections of the 100 qubit quantum computer). Alternatively, if they had two such 50 qubit devices (and presumably they will soon) they can verify the second one with the first much quicker than they can verify the first with a classical computer, so in that sense the quantum computer beats a classical computer at some task.

There's additional piece to this that you are missing: while the classical simulation is _hard_ (i.e. increasingly hard for larger and larger number of qubits or circuit depths), it _can_ be computed with enough computational power for small number of qubits <=50 and depths<=20. (To get the classical simulation to 50 qubits was an achievement in itself and required a huge amount of compute power provided by google, without which they'd probably be only able to compute it for 30-40 qubits.) And where the classical computer can compute the result, the quantum computer does get the same answer with some probability (not a particularly high probability in absolute sense, but much higher than you would expect than if the quantum computer didn't work.)

They explain in the paper that the quantity plotted in Fig. 4 can also be interpreted as a probability of zero errors of running the circuit. You can see that it goes down quickly with number of qubits and number of cycles, showing the need for either error correction or much improvement in future devices in order to get any useful calculations done. The win here is that the probability of success is non-zero, as they say in the paper: "A single bit or phase flip over the course of the algorithm will completely shuffle the speckle pattern and result in close to 0 fidelity". So the only way to get the right result is to have runs with zero errors.

I'm not an expert, but you are correct in that there is no error correction here, and error correction is still a long way off. Around 2016, realizing that running useful quantum algorithms was a long way away and there needed to be earlier roadmarks for quantum devices to signal the progress, the problem of "quantum supremacy" was introduced. The goal is to find the problem with the _easiest_ demonstrable quantum speedup (regardless of usefulness). They proposed a particular sampling problem (running a randomly chosen quantum circuit that has output with a positive probability on many bitstrings, where the exact "speckle pattern" of the probability distribution would only show up if no errors were made when running the circuit.) As the circuit is randomly chosen, it can serve no particular use, except for verification that the computer runs correctly. Relevant papers for more info: https://arxiv.org/pdf/1608.00263.pdf https://arxiv.org/pdf/1612.05903.pdf

It may be that the use of photons gives long coherence in these devices as compared to other types of potential qubits, but then you still have to ask about (coherence time) / (gate time).

Any evidence that these are quantum coherent devices? In seems like the only reference in the paper is that "future improvements" will allow entanglement generation. I don't think the use of "closes in" in the HN title would be appropriate if these are such early stage devices that they can't even put a number on the coherence time yet.

The quantum states only have discrete frequencies because they are bound states contained within a trap. If you consider H = p^2/2m, a free particle, the frequencies are continuous. The universe isn't a trap.

Oh, I see. The name is taken from the scientific paper linked at the top of the article. I couldn't read it, my comments were based on the article alone.

name was edited from "unreasonable effectiveness of CNN in genetic population" after I read it but before my comment was finished.

no examples of "unreasonable effectiveness" or even "effectiveness" are given; just a semi-plausible technique and some questions that might be worth answering. I hope the term doesn't get diluted with more examples like this.

also not clear why a 2D local representation is being used for 1D data. there is no meaning to the ordering of the rows (different individuals who represent the samples in the genome), so it doesn't make much sense to encode that into the image. I would presume that not much meaning comes from neighboring mutations that are separated by a long string of no mutations, so the in-row locality should be broken into chunks. Neither of these basic considerations is motivated in the text either.

I would guess there is no effectiveness of CNN at all on this data set and a different statistical technique should be used on this data set...

This seems to assume that the Court's initial resistance is a signifier that the policy was _truly_ illegitimate, and their eventual acceptance was a fake legitimacy being bestowed upon tyranny. However, there are plenty of times where the Court's initial resistance was the tyranny, and the eventual acceptance was to _remove_ legitimacy from an illegitimate policy. Besides the obvious cases where the supreme court upheld segregation, I would argue that on average the trajectory of the court has been towards properly legitimate policies under our Constitutional principles rather than towards greater and greater perversion of them. On other principles, like federal power vs states rights, there has been a clear trajectory but I wouldn't identify either side as clearly legitimate or clearly tyranny.