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Nope. Not possible. You are entirely your brain. Nothing more, nothing less.

You cannot reasonably claim to know this. Of course, your parent comment cannot know that "no arrangement of physical parts has come close to qualitatively being the same as a subjective experience" either, as long as he only has access to his own subjective experience.


I appreciate your point, but I think invoking Gödel's incompletness theorems in this context is taking them far out of their scope.


I guess that depends on what you believe Mathematics to be. Is it a representation of reality itself (maybe the ultimate reality) or is it just a human construct? I don't know.


It's a theorem that starts off with some assumptions, and gives you some implications. It does not say anything as general as "some things are unknowable in mathematics".


Is that article written by Mochizuki? Can you make sense of it?


It is not written by Mochizuki (望月新一), but rather by Shiraki Yoshinao (白木善尚). You can see his profile here: http://www.sci.toho-u.ac.jp/is/lab/shiraki_lab/shiraki.html

I didn't really get much from it even with some assistance, but the very first part is a quick dialogue about a universe king and a neighbor universe king exchanging New Years gifts. Section 7 is about the そっくりハウス and goes with the page you linked, but ends by saying something about the multiplicative and additive rotational properties have something to do with the different universes seeing each other. He compares the girl's excitement to Mochizuki's upon discovering the identical house inside of a house.

Someone with better command could give a much better summary, but I'd personally be more interested in the lecture Mochizuki gave himself on it IUTeich last week (according to his site).


Your build up progression is exactly the same as mine, only I interpret it as based on the major key III. I agree we're not talking about modulation in the usual sense, but I think it makes sense to think of it as a key change. It reminds my ears of the common IV-V-vi progression, only with a suprising major VI.


I have to disagree again... I don't think a III chord is anywhere in the entire song. The build up is in the parallel major.


Right, the key III is the parallel major. I'm shifting the base of the notation for this passage. When I say III ends the build up, I mean III in the parallel major key, i.e. V(7) in the original key.


III is the relative major. I is the parallel major. As I said, I believe there is no III anywhere in the song.


You're absolutely right. In my native language, the relative key is called the parallel key. Sorry for causing confusion.

So, to clarify, I'm not claiming there is a III in the original key, I'm referring to the III chord of the relative major key.


I think I have to a disagree with your analysis. The verse is in a minor key judging by the looping riff. This is interrupted once in a while by a iv-v-i cadence, and then the verse continues. Then the build-up, which happens in the parallel key III: IV-V-VI-VI IV-V-III-III-III and then back to the minor key for the chorus.


Could someone explain what an attractor is? I looked it up on Wikipedia, but I don't understand how these shapes benefit from the definition given there.


The Wikipedia explanation is a fine one. To simplify -- it's when you observe a variable moving through through a space. In programming this means taking a coordinate or set of coordinates, and repeatedly feeding it into a function that will move the coordinates to a new location.

In this case, the heart of the function is:

    x = ((sin(xSeed * y) - cos(ySeed * x)) * width * 0.2) + width / 2
... and the same for "y".

(http://jashkenas.s3.amazonaws.com/misc/deJong/docs/deJong.ht...)

In our attractor, every time the coordinate pair lands on a new spot, that spot is exposed to a little bit of light.

What you can do for "x" and "y", you can also do for "z". If you generalize the deJong attractor into 3 dimensions, it looks like this:

https://www.youtube.com/watch?v=PrXe4RwtZpQ


Could you explain why is it significant that points seem to cluster around some specific trajectories / coordinates?


This equation is an "attractor" because the coordinates remain close to particular points (in this case, the origin).

Not all iterated functions behave this way -- sometimes the coordinates will wander off, and that would be called a "repellor" (http://en.wikipedia.org/wiki/Repellor).

"sin" and "cos" are good primitives for building attractor functions, because they naturally stay bounded close to the origin -- "x²" for example, wouldn't work nearly as well.

As to why the deJong attractor draws particular trajectories ... that's the beauty and mystery of the thing. It's also interesting how it tends to draw particular types of shapes when seeded from different areas -- dusty spheres when seeded close to the origin, skinny loops in the 4th quadrant, folded sheets of cloth in the 1st and 3rd, and stacked diamond circles when seeded in the 2nd.


Actually, the attractor in a dynamic system is the equivalent of an asymptote in a standard function.

Since the points cluster around it, it is revealed by plotting the values of the system.


It would be interesting to read the proof that de Jong's function has an attractor. Do you know where I could find it?


So an attractor is the image of a recursively defined function?


The attractor is technically the set of points that the iterated value traces.

In this case, the image is produced by iterating the "x" and "y" values, and slightly exposing with a white light every "(x,y)" position they stop at. The more they stop at a particular pixel, the brighter that pixel becomes.


My impression is that it has to do with the perceived commerciality of the entity doing/facilitating the copying.


Out of curiosity, are you unlikely to use the code because it's C++ or because it comes from Facebook?


C++.


I realise this is a dangerous subject, but I am genuinly curious: given the business you run and the work you do for the Freebsd team, why would you object to using c++, but not c?

I could understand why you would object to both, but why only the lower level language.


Personally, I can't keep all of how C++ works in my brain at once. Most people end up limiting themselves to a "sane subset" of C++ to compensate for spec sprawl. But, everybody picks a different subset, so you can quickly stumble on things you think you know but don't work quite right when working on non-self-originated code.


given the business you run and the work you do for the Freebsd team

Are you getting confused between tptacek and me?


Hey, why don't you use C++? :)


I think Tavis put it best: C is easier to audit because it's transparent. With C++ you can have innocuous-looking source code and have the compiler doing all sorts of crazy things behind your back.


I don't work for the FreeBSD team.


The inconsistent placement of the "this" argument in function calls seems to support this being C. The vtable moving around would indicate that each class layout is hand-written, though.


Yeah, the author made a point of noting "this" could be in a register or the stack, but that to me just says "C". The functions moving around wouldn't necessarily mean it is written by hand, though. There just needs to be some rules governing the system and we don't know what those rules are (yet).

I would just be very surprised if this is anything other than some convention developed on top of C.


Differing calling conventions can point to combination of hand crafted object system in C with some custom code generator with some high level input that produces machine code directly without C in between. When you generate machine code that does not directly interface with system libraries it is often useful to ignore platform ABI calling conventions and make up your own.


Perhaps they use some kind of right-to-left fastcall convention. Or maybe they are just unconventional, putting "this" at the end of the parameter list, hence ending up in different registers or the stack depending on the number of arguments?


I don't immediately see why it would be putting arbitrary data in front of the vtable unless it's done by a person. Do you have any ideas?


Perhaps if they posted more examples.. I could see it being useful to put the "data" before the vtable in certain types so that one could simply cast the type to get the value instead of having to call an accessor function. A string type could have the char* as the first member. A linked list could have the data void* as the first member. If they posted a complete list of all the types they have found and which ones had non-standard vtables, it might be easier to make a call on whether it was done by hand or not.


At 28:35 he says: "This is a 100% match with what you see here. The most telling evidence are the missing dots here and here. These are your missing dots".

Which dots is he referring to? There are two prominent missing dots on the computer screen, but they are not present in his Stuxnet model.


He's talking about the screen on the right. Green dots indicate a centrifige, white dots indicate none. You can see the patterns line up with the table on the slide.


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