Search found 752 matches

by Robert'); DROP TABLE *;
Fri Oct 06, 2017 1:34 pm UTC
Forum: News & Articles
Topic: The Darker Side of the News
Replies: 4084
Views: 534411

Re: The Darker Side of the News

This section is kinda weird. Investigators say the employee does not appear to have intended to let the sensitive cybertools escape to the outside world. Officials believe he took the material home — an egregious violation of agency rules and the law — because he wanted to refer to it as he worked o...
by Robert'); DROP TABLE *;
Thu Oct 05, 2017 12:00 am UTC
Forum: General
Topic: Thoughts for ships
Replies: 90010
Views: 7837072

Re: Thoughts for ships

https://xkcd.com/875/ wrote:2017 called, but we couldn't hear what they were saying over all the screams.
by Robert'); DROP TABLE *;
Tue May 02, 2017 8:12 pm UTC
Forum: Mathematics
Topic: Halting Problem
Replies: 208
Views: 31002

Re: Halting Problem

I don't know how useful this example is, because it doesn't map very well to the actual actions we have the machines/programs perform, but it might help illuminate the logic and structure of the argument a bit. Imagine that we visit the mystic oracle (who is a person) who lives at Delphi. The oracle...
by Robert'); DROP TABLE *;
Sun Oct 30, 2016 2:24 am UTC
Forum: Coding
Topic: Efficiency of prime sieve
Replies: 7
Views: 6237

Efficiency of prime sieve

I've recently got interested in the problem of computing primes less than a certain ceiling and I've hit a roadblock, but it feels like a matter of not being well-read enough to work around it rather than being somehow fundamental. I started with a brute-force Sieve of Eratosthenes and quickly reali...
by Robert'); DROP TABLE *;
Sun Oct 23, 2016 1:15 am UTC
Forum: Science
Topic: Is entanglement that surprising?
Replies: 27
Views: 6795

Re: Is entanglement that surprising?

I understand that, although it still sounds conceptually strange. Is it possible to write the dynamics equations purely or mostly in terms of how correlations evolve, or something like that? Some other way of looking at the model to make the correlations rather than the absolute states the first-cla...
by Robert'); DROP TABLE *;
Sat Oct 22, 2016 6:57 pm UTC
Forum: Mathematics
Topic: Primes under different moduli
Replies: 4
Views: 2441

Re: Primes under different moduli

The question originally occured to me in the process of trying to make a Sieve of Eratosthenes more memory-efficient, so that's a bit of a facepalm moment. I also knew that the list could get ridiculous quite quickly, but didn't particularly care since I was planning to have the computer do the actu...
by Robert'); DROP TABLE *;
Sat Oct 22, 2016 4:01 pm UTC
Forum: Mathematics
Topic: Primes under different moduli
Replies: 4
Views: 2441

Primes under different moduli

So I think it was this forum where I originally learned that all primes above 3 are of the form 6k+1 or 6k+5, meaning that if you want to search for primes, you can do so 3x as efficiently as searching evey single integer. However, I'm curious about whethere there is a value better than 6 to use tha...
by Robert'); DROP TABLE *;
Thu Oct 06, 2016 10:33 pm UTC
Forum: Mathematics
Topic: Why does x=y -> f(x)=f(y)?
Replies: 12
Views: 3294

Why does x=y -> f(x)=f(y)?

One of the first rules of basic algebra is that if you have an equation, you can transform both sides with the same function to produce another valid equation. However, from a foundations perspective, which axiom(s) actually imply that this is true?
by Robert'); DROP TABLE *;
Tue Sep 27, 2016 11:57 pm UTC
Forum: Science
Topic: Is entanglement that surprising?
Replies: 27
Views: 6795

Re: Is entanglement that surprising?

That approach rubs me the wrong way. While I'm sure its mathematically valid, it seems iffy to imagine it that way, given that the actual theory of QM (AFAIK) talks about the states of particles in fairly absolute (although non-classical) terms, not in terms of abstract correlations, i.e. the state ...
by Robert'); DROP TABLE *;
Fri Sep 23, 2016 5:17 pm UTC
Forum: Coding
Topic: Question about multithreading and multiple readers one writer (c++)
Replies: 4
Views: 4603

Re: Question about multithreading and multiple readers one writer (c++)

I may have misunderstood the question, but what actually performs the shared write? Do the searchers' changes somehow become visible to the other searchers?
by Robert'); DROP TABLE *;
Fri Sep 23, 2016 5:13 pm UTC
Forum: Science
Topic: Excluding the phylogenetic relationship from a phylogenetic vector
Replies: 3
Views: 1991

Re: Excluding the phylogenetic relationship from a phylogenetic vector

Yup, operator.mul is the right name. I hadn't actually done any testing, so I didn't notice that adding all the components of the two vectors together didn't do anything useful.
by Robert'); DROP TABLE *;
Thu Sep 22, 2016 12:55 am UTC
Forum: Science
Topic: Is entanglement that surprising?
Replies: 27
Views: 6795

Re: Is entanglement that surprising?

The point is these two descriptions are the same. What turns out to be important in the case of the electrons is that you can randomly pick whether you measure the x component of spin or the z component of the spin AFTER the spins have been separated but you will see correlations in the measurement...
by Robert'); DROP TABLE *;
Sun Sep 18, 2016 1:50 am UTC
Forum: Science
Topic: Is entanglement that surprising?
Replies: 27
Views: 6795

Is entanglement that surprising?

In Newtonian physics, objects have state, and the state has a "definite" value chosen out of some set of possibilities. In the case of an object's position, that set might be the entire space. In the case of something like an object's orientation around a particular external axis, that set...
by Robert'); DROP TABLE *;
Wed Sep 14, 2016 6:40 pm UTC
Forum: Science
Topic: Excluding the phylogenetic relationship from a phylogenetic vector
Replies: 3
Views: 1991

Re: Excluding the phylogenetic relationship from a phylogenetic vector

From my reading of the paper, I'd have understood the operator to mean |v i > - (|u> <u|)v i >, which I don't think produces the same answer. I have no specific experience in this area, though, so that might not make sense for some other reason. However, here's an example of how you might write your...
by Robert'); DROP TABLE *;
Thu Jul 28, 2016 11:42 pm UTC
Forum: Coding
Topic: Coding: Fleeting Thoughts
Replies: 9864
Views: 1766983

Re: Coding: Fleeting Thoughts

FT: I need to pay more attention when the compiler warns, "Implicit declaration of function." Especially when that function returns something other than int32.
by Robert'); DROP TABLE *;
Thu Jul 07, 2016 11:21 pm UTC
Forum: Coding
Topic: Coding: Fleeting Thoughts
Replies: 9864
Views: 1766983

Re: Coding: Fleeting Thoughts

Right now I'm awaiting on all the immediate children of a node coming in at once then processing them. So each node isn't "complete" till all its descendants are retrieved, but it won't care about if siblings are still processing or anything. I was sort of looking at doing something like ...
by Robert'); DROP TABLE *;
Tue Mar 08, 2016 7:45 pm UTC
Forum: Coding
Topic: The "IT DOESN'T WORK!" thread
Replies: 1958
Views: 513828

Re: The "IT DOESN'T WORK!" thread

It somehow didn't occur to me that someone else might have encountered the same problem precisely enough that googling the result was useful. (And also that I seem to be persistantly unable to remember which way around endianess goes.) It worked as soon as I corrected that, thanks for the pointer.
by Robert'); DROP TABLE *;
Tue Mar 08, 2016 12:30 am UTC
Forum: Coding
Topic: The "IT DOESN'T WORK!" thread
Replies: 1958
Views: 513828

Re: The "IT DOESN'T WORK!" thread

So I decided to write an implementation of md5 in order to practice Rust, and now I have the following, based on the psuedocode on Wikipedia : pub fn compute(data : &Vec<u8>) -> [u8;16] { use core::ops::Not; let k : [u32; 64] = [ 0xd76aa478, 0xe8c7b756, 0x242070db, 0xc1bdceee, 0xf57c0faf, 0x4787...
by Robert'); DROP TABLE *;
Mon Jan 25, 2016 2:46 am UTC
Forum: Fictional Science
Topic: LHC-powered rocket
Replies: 4
Views: 4388

LHC-powered rocket

If you could somehow use the LHC's main 7TeV beam as a rocket exhaust, and disregarded the mass of the accelerator itself, how effective would it be? (The specific situation I'm thinking of involves a portal inside the accelerator connected to the end of a spaceship, but that's not important to the ...
by Robert'); DROP TABLE *;
Sun Jan 10, 2016 9:20 pm UTC
Forum: Mathematics
Topic: Upper bound on max shifts / BB function on UTMs
Replies: 2
Views: 1587

Re: Upper bound on max shifts / BB function on UTMs

We can create a turing machine to test each of these statements as described before, and since each of these machines can be run on any universal turing machine, it suffices to find an upper bound on S(n,m) for any universal turing machine in order to know when to stop. This sounds a bit of a dead ...
by Robert'); DROP TABLE *;
Mon Dec 21, 2015 12:52 am UTC
Forum: Coding
Topic: Coding: Fleeting Thoughts
Replies: 9864
Views: 1766983

Re: Coding: Fleeting Thoughts

FT: Doing a recursive search to solve the n-queens problem and using futures to paralelize the branches turned out to be a lot slower than I was expecting. Although I guess since running this doesn't actually take up much CPU time, the problem is the scheduling rather than any ineffiency with the al...
by Robert'); DROP TABLE *;
Sat Dec 05, 2015 2:13 am UTC
Forum: Science
Topic: Miscellaneous Science Questions
Replies: 2870
Views: 639877

Re: RELATIVITY QUESTIONS! (and other common queries)

For this radiation to have been able to escape, it must have started out with an enormous energy close by the black hole horizon. But if such an enormous energy was located there, then an infalling observer should notice and burn to ashes. This however violates the equivalence principle, according ...
by Robert'); DROP TABLE *;
Mon Nov 30, 2015 7:56 pm UTC
Forum: Mathematics
Topic: hotel infinity and countably infinite
Replies: 31
Views: 4572

Re: hotel infinity and countably infinite

Cradarc wrote:N2 is indeed > N

By what notion of ">"?
by Robert'); DROP TABLE *;
Fri Nov 06, 2015 1:05 am UTC
Forum: Science
Topic: Miscellaneous Science Questions
Replies: 2870
Views: 639877

Re: RELATIVITY QUESTIONS! (and other common queries)

Well for one thing as you're falling in, you're also going faster and faster, so the time dilation doesn't actually go to infinity like it would if you were hovering closer and closer to the EH. While I'll happily accept math to the contrary, I can't quite get this explanation to work in my head - ...
by Robert'); DROP TABLE *;
Sun Oct 25, 2015 9:55 pm UTC
Forum: Science
Topic: Miscellaneous Science Questions
Replies: 2870
Views: 639877

Re: RELATIVITY QUESTIONS! (and other common queries)

What does Hawking radiation look like as you fall into the black hole? As seen from infinity, the temperature of the radiation and tidal force at the EH become arbitararily low as the hole gets heavier, but the time dilation at the EH always decreases arbitararily close to zero regardless of the hol...
by Robert'); DROP TABLE *;
Wed Oct 14, 2015 12:36 am UTC
Forum: Fictional Science
Topic: How badly does this supertechnology break thermodynamics?
Replies: 15
Views: 8870

Re: How badly does this supertechnology break thermodynamics

Judging by the portions of that page that I understand, I'd guess that even if you got all your math right (which is far from certain) there may be a units problem that makes the number you got mean something very different. I'm pretty sure the units in the formula at the top of the page come out t...
by Robert'); DROP TABLE *;
Sun Oct 11, 2015 7:18 pm UTC
Forum: Fictional Science
Topic: How badly does this supertechnology break thermodynamics?
Replies: 15
Views: 8870

Re: How badly does this supertechnology break thermodynamics

The program logic works as follows: 1) If no message received, then send message. 2) If message received and <unlikely event X> did not happen, then do not send message. 3) If message received and <unlikely event X> did happen, then send message. The universe forces a consistent outcome to happen. ...
by Robert'); DROP TABLE *;
Tue Sep 29, 2015 12:05 am UTC
Forum: Coding
Topic: Coding: Fleeting Thoughts
Replies: 9864
Views: 1766983

Re: Coding: Fleeting Thoughts

(Yay, another question-laden post. Thanks for the help and explanation so far, I've learned a lot more than trying to scrape the various wikis.) This isn't true. However, X->(Y->Z) is equivalent to (X, Y)->Z, where (X, Y) is a tuple type. (E.g., a function add(x, y) = x + y can be written as a funct...
by Robert'); DROP TABLE *;
Sat Sep 26, 2015 1:57 am UTC
Forum: Coding
Topic: Coding: Fleeting Thoughts
Replies: 9864
Views: 1766983

Re: Coding: Fleeting Thoughts

FT prompted by both Xanthir's help and the Codeless Code: Given, 1) that a functor lets you turn a function (X -> Y) over the category you're "lifting" into the functor into one with signature (F X -> F Y). 2) that you can slice multi-value function signatures into any precedence you want,...
by Robert'); DROP TABLE *;
Sat Sep 19, 2015 3:41 pm UTC
Forum: Fictional Science
Topic: How badly does this supertechnology break thermodynamics?
Replies: 15
Views: 8870

Re: How badly does this supertechnology break thermodynamics

I guess what would happen is just that the message will never be received. I think you can get around that if you program the machine to send the message if it both hasn't received it in the past and the horribly unlikely thing hasn't happened, but then change the condition when it receives the mes...
by Robert'); DROP TABLE *;
Sat Sep 19, 2015 1:33 am UTC
Forum: Fictional Science
Topic: How badly does this supertechnology break thermodynamics?
Replies: 15
Views: 8870

How badly does this supertechnology break thermodynamics?

(The entire following post is speculation about the counterintuitive physics surrounding an impossible device. I might've messed up at some point in the logic.) I'm writing a mid-future sci-fi story that involves a computer that contains a small time machine, and works on self-consistent time-loop l...
by Robert'); DROP TABLE *;
Mon Sep 14, 2015 12:14 am UTC
Forum: Coding
Topic: Coding: Fleeting Thoughts
Replies: 9864
Views: 1766983

Re: Coding: Fleeting Thoughts

(Oops, this turned into a post full of questions, as I'm trying to square the classical way of doing things with the functional way) Let's think of a mutable object as a function that take some transformation instructions and returns an immutable version of itself with the transformation applied. In...
by Robert'); DROP TABLE *;
Sat Sep 12, 2015 10:25 pm UTC
Forum: Coding
Topic: Coding: Fleeting Thoughts
Replies: 9864
Views: 1766983

Re: Coding: Fleeting Thoughts

Well, the nice thing is that a compiler can optimize around this. (depending on the complexity of the compiler and the structure of the language, of course) In a language like Java, you'll have a hard time trying to deal with transforming immutables efficiently, since the language doesn't lend itse...
by Robert'); DROP TABLE *;
Sat Sep 12, 2015 7:47 pm UTC
Forum: Coding
Topic: Coding: Fleeting Thoughts
Replies: 9864
Views: 1766983

Re: Coding: Fleeting Thoughts

FT inpsired by this thread : The prime disadvantage of using immutable objects everywhere is that each transformation of the object involves allocating a new one, and usually deallocating the old one. So how sensible is this pattern? (I have a suspicion that it's sensible because it's actually a poo...
by Robert'); DROP TABLE *;
Tue Sep 01, 2015 1:01 am UTC
Forum: Coding
Topic: Help building a parser combinator?
Replies: 10
Views: 3998

Re: Help building a parser combinator?

Your serialization and deserialization code should be the same code, so they stay in sync automatically. How is this actually implemented, though? Getting from a stream and storing in a struct seems to be fundamentally different than the reverse. (A,B)->C represents "a mapping from types (A,B)...
by Robert'); DROP TABLE *;
Sun Aug 30, 2015 12:13 am UTC
Forum: Coding
Topic: Help building a parser combinator?
Replies: 10
Views: 3998

Re: Help building a parser combinator?

b) you're ok with those data types being an exact match to the binary format. Your objects' attributes are going to have types like uint16_t instead of int, but that's fine with you. In that case, just define your objects with the correct types and attribute order, and have the compiler do the rest...
by Robert'); DROP TABLE *;
Thu Aug 27, 2015 1:00 am UTC
Forum: Coding
Topic: Help building a parser combinator?
Replies: 10
Views: 3998

Re: Help building a parser combinator?

If you want to combine multiple production rules into one in an LL(1) language*, every alternative must have a distinct first token/character. My understanding is that the OP has a fixed binary data format, and not anything that can be a parsed as a language. It sounds like s/he wants something lik...
by Robert'); DROP TABLE *;
Tue Aug 25, 2015 1:17 am UTC
Forum: Coding
Topic: Help building a parser combinator?
Replies: 10
Views: 3998

Help building a parser combinator?

I am currently building a program to read files from a legacy system originally built in 1999-era C, so each file involved is a opaque series of bytes that would be meaningless without the format specification. (Which I thankfully have.) The actual data/format itself is not any more structured than,...
by Robert'); DROP TABLE *;
Fri Jun 05, 2015 8:58 pm UTC
Forum: Computer Science
Topic: What's the complexity of "proving a given theorem?"
Replies: 1
Views: 3852

What's the complexity of "proving a given theorem?"

That is, given some formal system/language, and a sentence in tha language that can be assumed to be a valid theorem of the system , what is the time/space complexity of actually finding a proof of the sentence? Obviously, the problem is somewhere within EXPTIME/EXPSPACE, since doing a brute-force s...
by Robert'); DROP TABLE *;
Sun May 17, 2015 4:40 pm UTC
Forum: Computer Science
Topic: Secure multiparty cryptography?
Replies: 7
Views: 4751

Re: Secure multiparty cryptography?

Do I have the parameters of the question correct? Yes. Your post seems to suggest that the number of required signatures is equal or larger than the number of total signatories, but I put that down to either misreading or it getting mangled on the way between brain and keyboard. Another question, I...

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