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CaptainNegative

606 karma · joined May 2, 2021

https://yonatan.us
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CaptainNegative··on Hezbollah pager explosions kill several people in Lebanon
Why would you assume this targeted three people? I assume the most likely scenario is that the attackers targeted as many Hezbollah members as they could, and were extremely successful at it.
CaptainNegative··on Euclid's Proof that √2 is Irrational
This proof has almost nothing to do with Euclid. The Pythagoreans knew about it more than a century before his birth (Hippasus was apocryphally killed for divulging this proof), and the proof is widely believed to have only been inserted into Elements by others after Euclid's death.
CaptainNegative··on A simple proof that pi is irrational [pdf] (1946)
I don't think that follows at all. Any series of rational numbers that converges to a rational (such as any appropriate geometric series) will still converge to a rational if you remove any finite or co-finite subset of terms.
CaptainNegative··on How to use the Bitwarden forwarded email alias generator
In principle, someone seeing heido15wkj6@yourraredomain.com, yua16ooaaj2@yourraredomain.com, and kqoq91inhi4@yourraredomain.com in a dump might be able to infer that all of these belong to the same user with a catchall address (especially if they can verify that the domain is unpopular via dns caching or other tricks). Using a common service adds another partial layer of anonymity between the email addresses, making one harder to track.
CaptainNegative··on The Point of the Banach Tarski Theorem (2015)
Assuming the usual consistency caveats, the paradox is no longer a theorem of ZF+DC, but its complement isn't either. So in that case the analogue to the fifth postulate is even stronger, as there are both models in which you get the counterintuitive results of unmeasurable sets and those in which you don't, and the axioms are not strong enough to distinguish the two.
CaptainNegative··on What happens to latency if service time is cut in half (2022)
A simple way to view the first statement is that by both doubling the request rate and halving the processing time, you're effectively speeding up time by a factor of 2. If you were to record a video of the entire system, someone switching the parameters as you describe and someone putting the recorded video on a 2x fast forward would be fundamentally indistinguishable. So, naturally, the response time gets cut down on half as well.
CaptainNegative··on 'Irresponsible' to ignore consciousness across animal world scientists argue
There's not really any evidence for this. On a source-by-source basis, plant-based protein quality tends to be a few percentage points lower than from animal sources due to the differing amino acid distribution, but mixing sources like rice+pea gets you all you need. Soy is already pretty good by itself if you're okay with just consuming a tad bit more. Personally I just add a protein shake to my diet and that more than makes up for the difference relative to my carnist days.

The micronutrients that vegans need to watch out for are EPA/DHA (types of omega 3s) and Vitamin B12. Both are trivial to supplement, and not particulary expensive (especially now that Costco sells the former). The B12 you get via factory farmed meat is all supplemented to them anyway, so there's no difference in some hypothetical molecule quality.

The last remaining micronutrient that might be tricky is Vitamin D3, if you don't get the necessary sun exposure. The D3 in standard supplements is usually made from sheep wool. But you can also replace that with relative ease, and many vegan options are really mixed D3+K2 supplements which is even better. Also available at Costco, for what it's worth.

CaptainNegative··on The Mystery of 'Jia Tan,' the XZ Backdoor Mastermind
From the article

> The backdoor’s careful design could be the work of US hackers, Raiu notes, but he suggests that’s unlikely, since the US wouldn’t typically sabotage open source projects—and if it did, the National Security Agency would probably use a quantum-resistant cryptographic function, which ED448 is not.

I'm not personally knowledgeable enough to assess this claim.

CaptainNegative··on CA train project needs another $100B to complete route from San Fran to LA
The article is using short scale billion, thank the lord. (note: parent comment was edited)
CaptainNegative··on CA train project needs another $100B to complete route from San Fran to LA
That's only $180k per meter.
CaptainNegative··on FDA clears first over-the-counter continuous glucose monitor
The only symptoms needed are a pulse, the ability to type out a credit card number, and availability for a sham phone call. It's virtually impossible to not get prescribed one from a mill.
CaptainNegative··on ACT-R the theory is embodied in ACT-R the software
I had a similar impression when I took a course on the matter ages ago. I don't have a better cognitive model, but the methods we were shoehorned into with ACT-R were so different from the actual cognitive processes I undertake in completing the same tasks that it all felt so pointless. Short of results derived from massive hyperparameter tuning to overfit existing data, has ACT-R shown any real-world explanatory power?
CaptainNegative··on Show HN: Beeper Mini – iMessage client for Android
Gaim
CaptainNegative··on OpenAI researchers warned board of AI breakthrough ahead of CEO ouster
Here's a simpler example that works.

Q: Prove that if cos(x) is an integer then so is sin(x).

A: The statement "if cos(x) is an integer, then so is sin(x)" is not true in general. To understand why, let’s consider the properties of sine and cosine. [...]

It had trouble when the problem domain is different from the usual one the same keywords typically fall into.

CaptainNegative··on The 8000th Busy Beaver number eludes ZF set theory (2016)
If you can check any given bitstring for whether it encodes a valid ZFC proof of the (in)consistency of ZFC in finite time, then you can write a program to enumerate over all possible bit strings in shortlex order and halt the first time you see a valid proof.
CaptainNegative··on LinkedIn Issues Warning to Site Shaming Pro-Palestinian Sentiment
How do you read that other than as "if you have humanity, you support Palestine", which is semantically equivalent to "if you don't support Palestine, you have no humanity"?
CaptainNegative··on LinkedIn Issues Warning to Site Shaming Pro-Palestinian Sentiment
> ... and you don't have to be a Muslim to support Palestine, you just have to be a human being

One can support innocent Palestinians without supporting Palestine, the same way one can support innocent Israelis without supporting Israel. Not sure why they decided to sneak in some dehumanization into what masquerades as a positive sentiment.

CaptainNegative··on Playing Pokemon Red with Reinforcement Learning
If it were just up to randomness with an unmodified ROM, then (barring a glitch) they would have soft locked at the Safari Zone which costs some currency to enter and needs to be traversed to the Surf HM in a relatively tight number of moves. There's only a finite amount of money in the game, so they can only fail at most a few hundred times before the game becomes impossible to beat.
CaptainNegative··on Internet traffic in Israel surged 170% right after the Hamas attack
I speak Hebrew. The direct translation is "we will operate everywhere and with full force".
CaptainNegative··on How many animals get slaughtered every day?
And there's a lot of money poured into keeping it that way. Sonoma County, CA lets organized theft gangs roam free, but conjure up the ridiculous charge of felony conspiracy to commit misdemeanor trespass for someone saving sick ducks from a duck farm after authorities refused to act on reports of California Prop 2 violations.

The reason the DA couldn't go with burglary is because that would require the object taken to have positive value, and those companies don't want to claim they also sell slaughtered animals who were diseased to the verge of death. If they discard their bodies as they corpses they do, they are of no value to the farmers and thus could not have been the subject of a burglary.

CaptainNegative··on Terry Tao's generals (2012)
"Prelim" also sometimes refers to an exam taken shortly after entering a PhD program to ensure you belong there.

One of the grad schools I attended had both a written "prelim" in year 1 and an oral "qual" in year 2/3. The other just had an oral "general" in year 2.

CaptainNegative··on How large is that number in the Law of Large Numbers?
The dependence on sample size is not exponential, it's sublinear. The heuristic rate of convergence to keep in mind is the square root of the sample size, i.e. getting 10x more samples shrinks the margin of error (in a multiplicative sense) by sqrt(10) ≈ 3ish.

The exponential bit applies to the probability densities as a function of the bounds themselves, i.e. how likely you are to fall x units away from the mean typically decreases exponentially with (some polynomial in) x.

Of course, this is all assuming a whole bunch of standard conditions on the data you're looking at (independence, identically distributed, bounded variance, etc.) and may not hold if these are violated.

CaptainNegative··on Buffalo buffalo Buffalo buffalo buffalo buffalo Buffalo buffalo
James, while John had had "had had" had had "had had had had had had had had had had had had had had had had had had had had had had had had had had had had had had had had had had had". "had had had had had had had had had had had had had had had had had had had had had had had had had had had had had had had had had had had" had had a worse effect on John's computer program because the string buffer wasn't large enough.

In the context of two users putting inputs into a C program that doesn't sanitize user input.

CaptainNegative··on Injured person reportedly dies after Cruise cars block first responders
Yes? Please don't make us pull out the model trolley set again.
CaptainNegative··on Complexity theory’s 50-year journey to the limits of knowledge
> More pedantically, it’s possible for a polynomial solution to P=NP to exist without it running in polynomial time in python.

That's not true. Any Turing machine can be compiled into a Python program with at most cubic slowdown. More precisely, the number of Python bytecode operations executed will be at most quadratic in the running time p(n) of the TM, with all operation acting on a bounded number of objects of size O(log p(n)) (which for polynomial p() is just O(log n)).

One can check Chapter 1 of Arora & Barak's Computational Complexity book for a description of the C/Java analogue of this claim, but it follows from a straightforward simulation argument: literally just hardcode the TM states and transition model, then execute it. The only bit to be careful about is addressing and address sizes growing unbounded, but the max size is only logarithmic in running time (simple proof, I believe this is an exercise in Sipser's book), and that's why we give ourself a cubic buffer.

CaptainNegative··on Complexity theory’s 50-year journey to the limits of knowledge
The running time is polynomial, and there is some constant c independent of n (or X in your notation) such that the running time is O(n^c). The only "sleight of hand" is that we don't know what this c is.

Yet, provably, there is some constant c such that for absolutely no satisfiable input does the program take more than c*n^c steps to halt, where n is the length of the input.

Note that not knowing c doesn't mean we can't put an upper bound on c. For example, I believe (but don't quote me on this) that c can be upper bounded by Rayo's number. As, otherwise, I think we can derive a compact first-order expression for an upper bound on Rayo's number, which would be a contradiction. And, although Rayo's number is big, it's ultimately still a constant.

But ultimately none of this is necessary to prove that the problem is in P. The mere existence of the constant c independent of n suffices.

CaptainNegative··on Complexity theory’s 50-year journey to the limits of knowledge
I didn't say it solves every SAT problem in polynomial time, I said it can

> find satisfying assignments to satisfiable SAT instances in polynomial time

The distinction between this and solving SAT, and the slight strengthenings one can make to universal search, are part of those few technicalities I promised to gloss over.

Also, cut the snark. I'm not a complexity theorist, but my PhD thesis was in the intersection of graph algorithms and complexity (the first word of the title literally being "Hardness"), and I'm more than qualified enough to understand and present well-known complexity results from half a century ago, even when a misguided appeal to authority is at play.

CaptainNegative··on Complexity theory’s 50-year journey to the limits of knowledge
There's already a known algorithm M you can implement right now that can find satisfying assignments to satisfiable SAT instances in polynomial time conditioned only on P=NP.

Note: I'll be glossing over a few technicalities in this explanation, feel free to ask about them.

Roughly, the algorithm M is as follows. Suppose you have input x of length n. For each integer c between 1 and n, encode c in binary and try to decode it in UTF-8. If it decodes, try to interpret it as a Python program, and run it on input x for 100n^c steps. If it executes successfully and outputs a valid assignment, return the assignment. Otherwise, continue onto the next c. If c=n and you haven't found an assignment yet, do a brute force search over assignments and return what you find.

Now suppose P=NP, so some Python program finds SAT solutions in polynomial time. In fact, there are infinitely many such programs, since each valid program can be prefixed with as many "pass" expressions as we want. Interpreting the UTF-8 encoding of any such program p in binary gives us some integer c.

There are only finitely many inputs of length ≤ c, so the slowest of them still runs in finite (and thus polynomial) time. For any input of length > c, the above algorithm M will spend at most 100(c-1)n^c time trying to execute the (c-1) different strings in Python for at most 100n^c steps each. If M happens on a solution before then, great! If it doesn't, then now we run p -- which by assumption does find solutions in polynomial time -- for 100n^c steps.

If 100n^c is an upper bound on the true running time of p, then this necessarily returns a valid assignment, meaning that we can find assignments in time O(c n^c) time for some integer c, i.e. polynomial time. Otherwise, if 100n^c is too small, we just wait for the next copy p' of p (with a pass prefixed to it) that will have an even looser time bound of 100n^c' . This also may not be enough, but eventually we will find some p''''' for which the time bound does suffice (depending on the true running time of p). And so we find valid solutions in O(c'''''n^c''''') time.

None of this required us to know what p is; effectively M makes the non-constructive constructive by trying every program out in a systematic way that the running time never exceeds some (also unknown) polynomial bound.

Is it practical? Suppose that the shortest Python program finding SAT assignments is at least 100 bytes long. Then c > 256^100, and thus the running time is something like O(n^(256^100)). So be sure to get a good CPU.

CaptainNegative··on NP-hard does not mean hard (2017)
If you're allowing for some error probability, then the answer is trivially yes. For example, the NP-Complete problem of "does this graph have a clique of size sqrt(n)" is trivial over G(n, 1/2) random graphs, because the answer is No with overwhelming probability (something decaying exponentially in n or n^2). So you don't have to read the input before responding.

If you're referring to Las Vegas style (always correct) algorithms, then I don't think something along those lines can work. Reading a constant number t bits from a G(n,p) random graph yields each possible event with the constant probability (1/2)^t. So the expected running time is still at least some (small) constant times that of the failure case, which is still exponential.

Are you perhaps thinking of the average case problem Planted Clique, where the task is to distinguish between a "clean" random graph G(n, 1/2) and a "planted" one where we force some random set of, say, k=n^(1/3) vertices to induce a clique? While distinguishing a graph with a k-clique from one without one is NP-hard on general graphs, you can show that G(n, 1/2) graphs virtually never contain cliques as large as 3 log n, and hence brute force searching all 3 log n sized subsets of vertices for cliques (in subexponential time n^(3 log n)) will almost always lead you to the correct answer. And once you find a clique of size 3 log n, expanding it to n^(1/3) can be done quickly using a greedy algorithm.

CaptainNegative··on Montana loses fight against youth climate activists in landmark ruling
Yes. The text is here, https://leg.mt.gov/bills/mca/title_0000/article_0090/part_00... . It's very vague, probably intentionally, and the working interpretation is whatever the court just decided it is.
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