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I already have problems following Proposition 1 where they introduce a different DNF with twice the clauses of the original CNF than claim that maximizing the satisfied clauses in the DNF would also yield a maximum satisfied solution for the CNF.

It's a pitty they don't release any source code that we can unit-test against problems with known solutions (while also profiling run-time to stay within polynomial bounds) :)

edit: what am I missing, their reduction to a DNF seems unsuitable to me?

I read proposition 1 [1] to mean: they find an optimal solution for the DNF V∪X, then expect the corresponding CNF C to have at least as many satisfied clauses. However isn't that insufficient? I mean there could be an even better solution with more satisfied clauses in C, that are totally missing when only looking for solutions for V∪X. But maybe I'm just misunderstanding something.

[1] https://arxiv.org/pdf/2304.12517.pdf

Last time I read about that, the problem seemed to be buckling [1]. E.g. if you look at Euler's critical load [2] then the pressure that a slender column can withstand just depends on the aspect ratio of the column (imagine a vacuum airship that uses internal columns to withstand the air pressure). So scaling things up means, that the column's weight has to scale proportionally with total airship volume (and the (air) pressure is a constant anyways). See also these discussions here [3]. Disclaimer: I don't claim to understand any of this.

[1] https://en.wikipedia.org/wiki/Buckling

[2] https://en.wikipedia.org/wiki/Euler%27s_critical_load

[3] https://en.wikipedia.org/wiki/Vacuum_airship

I'd think that the distance limit for _terrestrial_ mobile networks comes from the guard interval of the OFDM modulation [1]. I.e. on longer distances the time-offset between different different reception paths (due to reflections) of the signal becomes so long that you cannot compensate those with just a complex gain-factor of the OFDM vectors.

AFAIR LTE (4G) even uses different guard intervals depending on rural vs. city setting because that time-offset is larger in rural areas (less base station density).

I would not expect those problems to be relevant for satellite communication as ground<->satellite does not suffer much of the multi-path signal propagation of terrestrial systems. (IIRC DVB-c sat-TV broadcasts did not even use OFDM, at least not for the older "v1" DVB-c standard).

[1] https://en.wikipedia.org/wiki/Orthogonal_frequency-division_...

Yes, I can see the cabinet from my window, so maybe less than 100 meters cable. Inside big cities that seems to be the state-of-the-art. They must have placed a lot of cabinets in recent years. I'm surprised those cabinets don't give up a noticeable amount of heat, they don't even have noticeable active cooling. That's a huge amount of DSP operations that they are running, like a hundred DSL modems crammed together. But maybe modern ASICs can run a single 17a VDSL line at a just few watts.

Right now the modem reports a (link layer) data rate of 98338000 bit/s. Wget tops out at 10.7 MB/s.

I'm currently on profile 17a, I pay for 100 Mbit (downstream), and get like 90 Mbit actual IP protocol bandwidth (wget tops out at 10.7 MB/s). But I think the ATM signalling that's still used on the underlying VDSL physical layer is eating a significant portion of the bandwidth (due to the high frame header overhead).

> You can't get these speeds with even VDSL..

That's not quite true. At least in germany, VDSL2 with "supervectoring" profile 35b [1] is routinely used, advertised as 250 Mbit internet service [2].

Technologically it's quite a waste of hardware resources and electric power to put these kind of data rates on old twisted pair copper cables (instead of using fiber everywhere), but that seems to be the status quo here right now.

(And I'd guess that the ratio of people being in need of satellite internet is much lower in germany than it is in the US).

[1] https://en.wikipedia.org/wiki/VDSL#Vplus/35b

[2] https://de.wikipedia.org/wiki/Supervectoring

> Interestingly, videos don't seem to count? It must be a written description?

Wondering the same myself. Googeling for this issue turns up this power-point [1] which seems to imply on page 6 that "electronic publications, on-line databases, websites, or Internet publications" are also considered as "printed documents". But this is just a power-point so who knows which standard gets applied in practice.

I get the impression that the "printed document" language got written before digital documents and the internet were a thing.

I am not a laywer, don't know a thing about the topic, this is not legal advice etc.

[1] https://www.uspto.gov/sites/default/files/documents/May%20In...

But you need to be aware of the downsides of becoming inadvertently over-reliant on GPS [1]

[1] https://en.wikipedia.org/wiki/Death_by_GPS

> Why not just use Evil, the VIM emulation layer.

To cite Xah [1]:

"xah-fly-keys.el is a modal editing mode for emacs, like vi, but the design of key/command choice is based on command frequency statistics and ease-of-key score. Most frequently used commands have most easy keys."

I can confirm, that the amount of work on the hands is extremely reduced with xah-fly-keys vs. vanilla emacs (depending on where you put the command mode switch), though I have no experience with evil or vi to compare against.

[1] http://xahlee.info/emacs/misc/ergoemacs_vi_mode.html

> Long love ergomacs!

I recently stumbled over, and started using (and modifying) Xah's "xah-fly-keys" emacs bindings, which are a somewhat more radical implementation of the ideas behind ergoemacs (e.g. use Emacs without any "chording", i.e. without ever having to press two keys at once apart from shift+letter).

[1] https://github.com/xahlee/xah-fly-keys

My not very well-informed take on the situation is: Yes, Emacs seems to make a lot of progress in many directions. Latest git master does have elisp native compilation support (via libgccjit). Various elisp semantics have been modernized (support for common-lisp style lexical closures).

Still it is rather lightweight (compared with, say firefox), you can download upstream source and compile&install it in minutes rather than hours.

> Also, the fact that it's not rewritable means that...

> 1. Security bugs[2] will never be fixed[3], rendering the hardware unsafe to use over time.

But on the other hand: security bugs will never be introduced post-manufacturing. Additional DRM cannot be forced onto you, after you bought the product. Or: DRM bugs that allow you to fully use your hardware cannot later be patched by the vendor.

I think this is called "green hydrogen" [1] which has application as an energy storage medium, but also more. Energy storage also does not imply, that that hydrogen needs to be turned back into grid electricity, but could be used for heating or for hydrogen cars.

[1] https://en.wikipedia.org/wiki/Green_hydrogen

I think the Linux desktop (at least when running under an xserver) does have an obscure keyboard-mouse function, see e.g. here [1].

This seems to be enabled by default when running the german-centric 'neo' keyboard layout ('setxkbmap de neo'), see here [2]. It is usable on the desktop that I'm typing this from (Devuan GNU/Linux with xfce4 desktop), tested it this moment (no numeric keypad on my keyboard, but with the neo layout Mod4 + right hand keys can be substituted for the numeric keypad)

[1] https://linuxreviews.org/HOWTO_use_the_numeric_keyboard_keys...

[2] https://www.neo-layout.org/Benutzerhandbuch/Tastaturmaus/

What about: DjVu [1]?

It's not very well known, but it's so elegant, and also efficient, especially for scanned files.

[1] https://en.wikipedia.org/wiki/DjVu

I don't know anything about the details here, but with usual linear algebra stuff, bandwidth depends on the size of the kernel that fits into the local memory inside whatever IC you use for your floating-point computation.

E.g. matrix multiplication of n×n square matrices has computational cost of n³ but bandwidth cost of n². Usuall a big m x m matrix is split into many blocks of n×n matrices (with m = k×n). If a n×n matrix fits into the local store of your CPU (cache or registers), then bandwidth cost for the m x m matrix product is k³×n×n = m×m×m/n, so the bigger the block-size 'n' that you can process inside the CPU, the less bandwidth you need.

edit: formatting

Whether liquid or not, running the formula for kinetic energy of the counterweight, I'm getting something around 1 GJ (gigajoule) for a weight of 1 ton at 1500 m/s [1].

According to this site [2] that's equivalent to around 200 kg of TNT. Even with the counterweight being mostly water, that's quite a lot of energy to disperse. How does one evenly spread out the water to a surface the size of a football field? Would that even be enough area to prevent a shock wave being reflected back at the launch equipment?

[1] https://calculator.academy/joule-calculator/#f1p1|f2p0

[2] https://www.convert-me.com/en/convert/energy/tntkg.html?u=tn...

Scott Manley talked on youtube about the centrifugal force on the wheel being around 10 thousand g (in the full sized version). So how do you build something that touches a tunnel at hypersonic velocity with many thousand tons of force without disintegrating? It's not like you can just add wheels or skates to your ejected mass (or the tunnel).

Yes, that's an intriguing idea.

What I came up with was this: the launch arm has a second mass inside it, that will move (via centrifugal force) away from the center, in the same moment the payload is released.

Of course, just having two payloads launch in opposite direction as you propose maybe has much less implementation problems (though I wonder how you stop that second dummy payload in a way that does not cause an earthquake or explosion :)

You are right, it does not say anything about the Permanent Court of Arbitration's decision on the matter. I was more trying to make the point, that various court decisions related to this matter (the original decision against chevron as well as the case against Donziger) seem to be cast into doubt by external "impartial looking" entities, turning the water very, very muddy here.

But then I must admit, that I do not have a very high opinion of "arbitration courts" in general, as often they seem to have various conflicts of interests with regards to how they earn money by being paid by parties bringing the cases (i.e. deciding against the interests of a party which usually provides high-income cases, would risk the court's own financing).

Interestingly, the United Nations Human Rights Office's has quite the opposite opinion regarding the Evron vs. Donziger case (the one in the US that lead to Donziger's house arrest) [1].

"The Working Group recalls that it is inherent to the proper exercise of judicial power that it be exercised by an authority that is independent, objective and impartial in relation to the issues dealt with, as asserted by the Human Rights Committee in relation to article 9 (3) of the Covenant. In the present case, the Working Group is of the view that Judge P did not act in a manner which was independent, objective and impartial in relation to Mr. Donziger’s case. Consequently, the Working Group concludes that the imposition of pretrial detention upon Mr. Donziger was in violation of article 9 (3) of the Covenant. "

[1] https://www.ohchr.org/Documents/Issues/Detention/Opinions/Se...

Talking about international bodies, we should also consider the opinion of the United Nations Working Group on Arbitrary Dention, which is that "Noting all the above, the Working Group concludes that the detention of Mr. Donziger lacks legal basis and is therefore arbitrary, falling within category I of the arbitrary detention categories referred to by the Working Group when considering cases submitted to it. ". See here [1] for the detailed opinion.

The amount of conflicting information on the Donziger case is quite staggering but maybe quite natural given that there is so much money at stake.

EDIT: updated to quote from and link to original working group document.

[1] https://www.ohchr.org/Documents/Issues/Detention/Opinions/Se...

The wikipedia page on Donziger [1] says that the main witness to those bribe accusations retracted his statement and gives [2] as a source for that retraction. It seems, that the US courts did not consider that retraction, though [1].

[1] https://en.wikipedia.org/wiki/Steven_Donziger#Kaplan's_2014_...

[2] https://www.vice.com/en/article/neye7z/chevrons-star-witness...

My take on it: you get "infinitely parallel" computation, generating "inifinetly parallel" results that are in superposition. Problem is, at the end you can only access your "infinitely parallel" result via a classical measurement, involving a wave function collapse [1].

For some problems, people have found ways to extract useful information via classical measurements, e.g. Shor's algorithm (in theory breaking RSA/DSA/ECDSA/DH/ECDH style public-key algorithms [1]). However in the general case this does not work (so AES and hash algorithms are safe for now).

[1] https://en.wikipedia.org/wiki/Wave_function_collapse

[2] https://en.wikipedia.org/wiki/Shor%27s_algorithm#Quantum_par...

In case anyone wonders, I think the same argument is made in a somewhat easier to understand way in one section of the the P vs NP wikipedia page [2].

But I think that would turn (b) into a special case of (a) i.e. a bizarre algorithm that is completely useless. And it would also be an algorithm of mostly unknown complexity (with P=NP, we'd know it to be ∈ P, but we won't necessarily know anything else).

[2] https://en.wikipedia.org/wiki/P_versus_NP_problem#Polynomial...

The difference is that coal contains carbon that has been locked inside the earth's surface for at least a few million years (if not longer).

Trees on the other hand contain carbon that those trees extracted from atmospheric CO2 while growing. Burning those trees merely returns CO2 to the atmosphere that was taken from it a few decades ago. If you do that in a balanced way (growing the same amount of trees that you burn at any point of time), you may create a cycle that does not affect long-term atmospheric CO2 concentration.

Can second the praise for the Epson Eco-Tank printers. Ink is cheap and lasts extremely long. Also I never had any problem with clogged nozzles etc which I used to face frequently on the cheaper printers. (though my Eco-Tank printer is black-and-white only which maybe alleviates many of those problems).

Also the integrated scanner worked out-of-the box for me under Debian, after I compiled and installed utsushi [1] from sources (edit: I'm only scanning from the utsushi command-line, no experience WRT integration with sane etc.).

[1] https://gitlab.com/utsushi/utsushi

Where I come from, big city etc. there seems to be not much time advantage of taking a car vs. taking a bike. After all a bike is very easy to park close to your destination and it's not affected as much by traffic jam (due to rudimentary cycling infrastructure and the ability to use side streets that are too narrow for rush hour drivers to consider).

WRT child transport: child transport bikes are seeing a rising adoption here, so it is feasible to bike to work and drop of your kid on the way. Kids will stay dry below the bike's rain cover, though of course the parent who cycles will need some upgrade to his clothing compared to what's needed when going by car (finding cloth that is both rain-tight but doesn't cause sweating takes some experimentation).

If you want to look at the spectrum of possibilities, have a look at e.g.

https://www.babboe.com/

https://www.bakfiets.nl/

https://www.urbanarrow.com/

http://www.nihola.com/home.html

https://yubabikes.com/

(just enumerating what bikes I see on a regular basis, this list would go on and on)

PS: you may also want to factor in the time spent on maintenance and bureaucracy (dealing with car insurance etc) and the extra monetary effort involved with owning a car vs owning a bike.

Well, the Cell CPU also had DMA engines that were fully integrated into the MMU memory-mapping, so you would have been able to asynchronously do a memcpy() while the CPU's execution resources were busy running computations in parallel.