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Primarily for the fun of it. There are some specific uses of large Mersenne primes in the Mersenne twister algorithm for generating pseudorandom numbers https://en.wikipedia.org/wiki/Mersenne_Twister, but in practice much, much smaller Mersenne primes are perfectly fine for that use, and indeed are much more practical. There are people who whenever you talk about large primes will claim they are useful for crypto, but that's not generally the case. The primes are too big for practical Diffie-Hellman (and there are specific reasons one might want to avoid using them for that), and they are not random primes in any sense so using them for any form of RSA would be really silly. That said, there's at least one mildly fun cryptographic algorithm whose proof of correctness relies on there being infinitely many Mersenne primes http://www.di.ens.fr/~vergnaud/algo0910/Locally.pdf, but no one has to my knowledge actually tried to implement the algorithm in that paper.

This and what should probably also be pointed out:

You can prove properties on given programs. For example one can mathematically proof that the following program will always correctly calculate the factorial of n for n >= 1(given all instructions run correctly):

factorial(n)
      if n == 1
            return 1
      return n*factorial(n - 1)

For bigger programs it becomes much more complex. However progress in software verification is allowing us to also carry out proofs for big programs (e.g. proofing the absence of run time errors in the primary flight control software of an Airbus A340 which consists of 132k lines of C code see here).

So it may very well be possible to proof the correctness of an algorithm deciding what/who to kill under the right assumptions.

There is a vast amount of quality information on the internet, even if it falls short of all information. Did you want lecture notes from a QFT class introducing Majorana particles, or an introduction talk on their relevance to condensed matter research, or a review paper covering research, or how about the previous papers (e,g. this one) from the very same author of the paper in the news here? Many of her previous papers are already available for free on ArXiV, and this one might be too. Sometimes there is a bit of delay with posting things there after they get published, but a huge amount of published papers on various physics topics are available for free, either there or on researcher's home pages.

Making something available is not the same as giving people the will to bother even looking for it, let alone actually reading and pursuing such topics. But if so motivated, there is much more easy to find introductory information now on the internet than in the library when I was in grad school, at the least due to numerous lecture notes available that would never have been available in the past because it took too much time to formalize things into an actual book. Plus now you can search if much faster, and even if a paywalled version is found, it takes literally ten seconds to find free versions for many papers.

Is it possible to have socialists ideas before the term socialism was coined? It doesn't matter what you were referencing, the idea you were conveying is a socialist one.

So you're saying that the proletariat of France were socialists before socialism was cool? What hipsters! For the record, proto-socialist ideas started popping up in France distinctly after the revolution. I suppose that these distinctions are lost on you, though, since you're using the word in a prejorative sense, not a technical one.

Did you read below that I will repeat it since you missed it, if you are saying they had it equally as good you need to find something that made up for a serf's lack of technology, like cell phones, clean drinking water, indoor plumbing, living quarters without livestock, cars, laundry facilities,... What area did the serfs have it better then migrant workers to make up for all those things I listed.

First, I'll reiterate my objection that those aren't things that migrant workers have, generally speaking. Second, I'll reiterate the response I offered earlier: leisure time and living space.

If they are only given enough not to riot then they are way over compensated.

Your "they" refers to people risking their capital, according to the rules of English grammar. There is no meaningful risk of them rioting, so that interpretation of your words doesn't make sense. I don't think you meant to refer to the poor either, since then you'd be saying that they should be paid less so as to cause riots. Riots are generally undesirable for a society, so that interpretation doesn't make sense either. I can't think of any other ways to parse this statement, so I'm genuinely not sure what you're trying to say here.

People are breaking the law just for the opportunity to go work as a migrant worker, that is a long way away from a revolt.

I'm glad you think so. You may think the distribution of wealth in this country is just fine, but 92% of Americans would disagree with you, despite the fact that a majority of Americans actually underestimate the actual inequity in wealth distribution. See aforementioned Forbes link as reference for this claim.

I repeat, yet again, this thread got rather long. I don't like that. The last time I participated in a thread this long, it got way too long. The lesson I learned there is that some people have trouble communicating with me, and that it takes a considerable amount of effort to resolve the issue. Since I'm not willing to dedicate sufficient effort to accomplish that in this thread, I think this is as good a time as any to throw in the towel.

The disclaimer I've added to the end of my last three posts (as well as this one) has been rather prophetic, don't you think? Perhaps you're interested in breaking the 76-post-long-thread record I set with bingoUV? That would be even more impressive with this disclaimer in place the whole time. I totally think you should go for it.

The defining characteristic of the serf class was that people born serfs would live their entire lives as serfs and their children would too. There was no pathway to move up classes.

It's all about the rate of change. Upward mobility is falling in the USA like a rock from the sky. Compare the total public debt to the ever-growing income disparity:
http://www.deptofnumbers.com/m...
http://piketty.pse.ens.fr/file...
These things do not bode well for those not born into at least the upper middle class, and specific examples to the contrary only speak to the legal and socioeconomic possibility of moving upwards, not the difficulty.

This password security checker is much more accurate.

Cool beans that covers this problem. As the paper mentions, the common and fast math for deconvolution (division in the s-domain) only works for uniform blur with a PSF. It seems like a more iterative approach is required since the easy math can't be used.

Is the group's works available online somewhere? I'd like to see their condensed style.

The Astrée static analyser (based on abstract interpretation) proved the absence of run-time errors in the primary control software of the Airbus A380.

First, the author is not against open source. In fact, Coverity is helping projects like FreeBSD by providing tools for developers.

Second, he is not comparing apples to oranges. He is using a metric, bug-rate in a wide sample. Then, he finds, interestingly enough, that proprietary software is very much scattered, but the ones on the top are 5 X less buggy than open source. This begs the question: why? This is what people should be discussing. Not saying he works for Microsoft and all that childish bullshit...

The *real* question is: what are those methods people developing mission-critical software use that open source hackers do not? My hunch is: formal methods, safe languages.

For instance, Ocaml http://www.astree.ens.fr/ was used in a sofware verification system for the Airbus A340 fly-by-wire system. Haskell is used by Galois Connection http://www.galois.com/ to develop secure protocols for the DoD. And there are many other examples, just look at the clients of vendors of Erlang (well known), Common Lisp, and Eiffel.

As long as the open source community sticks to C (and C++), we're all going to remain in this ridiculous situation that we are in today. In this day and age you can use a fast compiler for safer languages like ML, Lisp or Eiffel, but people insist programming like we're in the 70s.

I'd say at least since at least May, 2004. This is some pretty old news. Still, I hadn't been aware of it, so it's nice to know. You know, in case I ever actually have a need to digitally sign an email.

That's really quite unrelated, but I noticed your nick on some random page with a quote from one of your posts here, about 9/11. The post was great, I must say.
Bottom of http://www.eleves.ens.fr/home/rannaud/.

Do you really want software made for medical devices, airspace industry or nuclear industry, or the military, done with that philosophy ? I guess it is to bad that one of the main developers of operating systems today thinks that way.

Part of the problem lies in this overuse of C/C++ software and Algol-derived languages. Better languages are available today. Part of the solution is to move away from this dependency of C, without necessarily dropping C. An example is how OCaml was used to formaly verify the C code in the Airbus A340 fly-by-wire system: http://www.astree.ens.fr/ The Linux kernel seems to me like kid's play compared to an Airbus. In hard engineering disciplines, you are not entitled to an "opinion" like Torvald's.

Specs are for real. Lack of formal design of software has lead to the current situation of where a whole industry revolves around bugs. Increase in the use of formal methods is expected to rise, and Microsoft already has hired quite a few smart people (but they have that huge backwards-compatibility problem).

My nephew is an operator at a major park here in Texas I took a look see one time in their DC and one was running smalltalk and another was running f77.
The system is important but not as critical as you would think. If there is anything outside of range the system doesn't launch. For that matter sometimes when everything is within normal ranges it doesn't launch :)

ML, which is a language for weenies, was used in the verification of C code for the Airbus A340 fly-by-wire system, which proves it has no use beyond Academia, and was never used in industrial applications.
http://www.astree.ens.fr/

GOTO + Functional Programming, which of course = Call with Current Continuation

At which point your head explodes

http://www.lkb.ens.fr/recherche/qedcav/english/eng lishframes.html

Riiight, the links: *blush* http://www.tunes.org/ and http://www.eleves.ens.fr:8080/home/madore/computer s/tunes.html/

More about quines than you ever wanted to know.

> > For example, you might run smtp server on port 80 and http on port 25 and they would complete the tcp three-way handshake just fine.

> That would work if you ran a server destined to never offer serivces to even a small group of people, but for normal, practical usage, it's... well, useless.

Do you experience any problems when clicking for example this link? Google shows this exact link when you search for Unlambda, or even hit I Feel Lucky and get automatically redirected. Is that URL really "useless" for you?

> You can't accept SMTP traffic unless it's been directly MX'd from a "normal" server, you can't even bounce port 80 requests to the proper port since presumbly, you moved it OFF port 80 to prevent random connections or avoid upstream blocks.

I read grandparent as an example of switching www/mail ports but the original poster was trying to build a data center, not a mail server which is about the easiest thing to have off-site, even using the exact same domain as your on-site webserver, because in DNS system, MX can be different than A record.

Does it have to be a C code? In my opinion C is not nearly obfuscatable enough. What about BF or Unlambda? Or, better yet, Lingua Romana Perligata?

how about Brainfuck

Well, yes. Certainly. That was actually my first example. I only used the euphemism "BF" instead of this vulgar profanity, so this misunderstanding is, well, understandable.

C code that appears correct but does the wrong thing when counting votes.

Does it have to be a C code? In my opinion C is not nearly obfuscatable enough. What about BF or Unlambda? Or, better yet, Lingua Romana Perligata? Now when I'm thinking about it, I think PASM might be perfect for such a task, if only-- I know! Acme DWIM or Bleach compiled directly into PASM! With JIT!! Dear God, that would be so cool!!! But wait, they want C code, right... Wait a minute, Perl is written in C! So is Parrot! And they can be embedded in a C program! Sweet Heavens! What an idea!!!1 Gotta go.

If we elect the President by a simple plurality (or majority) then Presidential candidates will simply spend huge amounts of money in a few population dense markets. Your vote won't count unless you live in the North East, Los Angeles, and a few other places. And as a side effect the views of rural America won't be represented at all, they might as well not even vote. So if disenfranchising 40% or more of the population is your goal, by all means eleminate the Electoral College.

Nope, Relativity only says objects with mass cannot be accelerated to C or beyond. Actually what it says is, "If a object with mass were to be traveling at the speed of light then we'd have a non-zero number being divided by zero. And we don't know what that means."

Similarly with faster than light speeds, but in this case it would be a real number being divided by an imaginary number. And we don't know what that means.

At the core of quantum mechanics is the simple fact that you cannot measure without disturbing.

Again, nope. Try reading up on "quantum non-demolition measurement".

Those damned electric eels are always drowning me.

Brainf**k is a relatively simple stack based language. The only thing about it that makes it hard to understand is its very terse syntax. Unlambda and Whitespace has this as well, and in addition to this they are completely unreadable. The reasons are quite different though: Unlambda because there is absolutely nothing like it (wrapping your mind around a myriad of s's, k's, i's and `'s == pain. I've tried) and Whitespace is just impossible to read (and program for that matter) without the aid of a program that can convert it to something where you can actually tell the instructions apart.)

Two languages missing are: Io [...], REXX [...], ficl [...].

You have provided great examples. I would add another two: Unlambda, bf and maybe also Ook. Furthermore, let us not forget about Assembly. Seriously, I strongly believe that if kids today had learned those languages and tried to understand how computers really work, we will have much less Flash/JavaScript/PHP/MySQL "elite" (or "leet," if you will) websites shamefully vulnerable to trivial cross-site scripting and SQL-injection exploits. The problem is that script kiddies today don't want to learn anything, be it REXX, Unlambda, IMCC, Perl 6 or even valid ANSI C for God's sake. We have to do something about it. I agree with you.

Indeed! All this talk of Python and BASIC is silly. She should teach her mother Unlambda.

My favorite is Unlambda, which is entirely independent of natural language facticity:
Clickez ici. It's based on S,K,I combinators and "abstraction elimination."

..so you're saying Java 1.6 is going to be Unlambda?

Unlambda.
A language combining the efficiency and speed of Haskell with the maintainability and ease of use of Intercal.

Wow, a contest that I can enter a Unlambda program in... :)

For those of you who don't know PHP, just wait a version or two. It already supports VB, C, C++, Javascript and Perl style coding. Version 5 is basically Java. Expect Intercal, Unlambda, and BrainF*** support by version 7 or 8. If you know a Turing-complete language, chances are you'll be able to use it to code PHP by the end of the decade.

Sure it is. It lets you warp over to another unrelated part of your program. Except it's weirder, because it lets you kind of go "backwards" in time as well by returning to an older program state (while handing the "past" program a piece of data from the "future" you're exiting). Kind of like an exception, but it can jump anywhere, not just up the stack frame.

In fact this interesting page dedicated to call/cc describes:

At its heart, call/cc is something like the goto instruction (or rather, like a label for a goto instruction); but a Grand High Exalted goto instruction.

Don't forget unlambda ;)

> Real programmers directly input hexcodes using cat or copy con..

Amateur. Real programmers use nothing but S, K, and apply.

They are an extremely valuable analytical tool, because they're usually the easiest Turing-hard model of computation to implement in whatever theoretical construct that you're trying to prove is Turing-hard

And then you say:

it was straightforward to implement Turing machines in lambda calculus, but it took a couple of decades before theoreticians managed to formally implement lambda calculus in Turing machines

Hence it didn't turn out to be that easy to implement lambda calculus in Turing machines, right? In my experience lambda calculus is much easier to implement anything in (and yes, I have programmed both, much to my horror). In any case, in computational theory, Turing machines are still used, but usually in their lambda calculus incarnation (the search for the smallest universal Turing machine is done in combinatorial logic, a very nice branch of lambda calculus, or should I say unlambda calculus? Apart from practical use, LC has surplanted TM's as analytical tools as well.

You said: "If you do something to one of your photons, it will simply destroy the entanglement" This is wrong!! rubidium does not take any energy away from light therefore the catastrophic chaotic cascading you refer to does not have a chance to occur. See a nicely written article here:> or ENS home, here

This is not the first controlled-not gate for a quantum computing system but rather the first in this solid state system.

Other implementations of a controlled-not gate (or its close relative, a controlled-phase gate) include:

Caltech Quantum Optics implemented a controlled-phase gate between photons using a strongly coupled atom in a cavity.

Serge Haroche's group implemented a controlled-phase between an atom and a photon using microwave cavities and atomic Rydberg states.

NIST Ion Storage Group: implemented a two qubit gate (which could be turned into a controlled-not) and a four qubit gate using trapped ions.

NMR quantum computing has been implemented by various groups including the biggest quantum computation to date, factoring 15, done by Isaac Chuang's group (IBM and now MIT.)

A proof of principle implementation of a controlled-not in the linear optics quantum computing scheme has been implemented at the University of Queensland.

I'm leaving out quite a few other cool experiments: but the above links should give you a good idea of the what early steps have been taken in quantum computing.

thanks! Your other post was also useful, especially the one about call/cc

Confused better than ignorant? You decide.

http://www.eleves.ens.fr:8080/home/madore/programs /#prog_infinity

(test it at http://www.eleves.ens.fr/infinity/)

Check out unlambda too for a brainwreck.

http://www.eleves.ens.fr:8080/home/madore/programs /#prog_infinity

(test it at http://www.eleves.ens.fr/infinity/)

Check out unlambda too for a brainwreck.

No - distinguish between syntactic sugar, which gives you a new syntax to express what you could have said anyway, and real language features.

For example array access with [] in C is syntactic sugar, since you could do the same with pointer arithmetic - a[b] is exactly equivalent to *(a+b). However a declaration of an array variable:

int a[1000];

is _not_ syntactic sugar, since there is no other way to reserve space for a thousand contiguous integers on the stack. You could use malloc() from the standard library, but as you know that allocates on the heap and you have to free the memory afterwards.

(OK you could have a thousand 'int' declarations but I don't think it's guaranteed they will be a contiguous block in memory.)

As an example of a language with no syntactic sugar, look at Unlambda (although you wouldn't want to program in it). The language syntax is minimal but semantically it is a long way off from raw machine code.

Most mathematicians and computer scientists use a program called TeX to typeset their papers. TeX takes a .tex file as input and spits out a .dvi file, which can be postprocessed by drivers to produce PostScript or PDF files. TeX was written by professor Donald Knuth of Stanford University; the current version is still essentially similar to the 1983 version!

TeX has a horrible syntax and funky limitations, but there are so many available packages for it (such as LaTeX and the associated packages) as well as external applications (BibTeX) and tons of mathematical files made for it that it just cannot be replaced.

Some crazy people even use TeX to
typeset a newspaper and a personnel directory.

Most mathematicians and computer scientists use a program called TeX to typeset their papers. TeX takes a .tex file as input and spits out a .dvi file, which can be postprocessed by drivers to produce PostScript or PDF files. TeX was written by professor Donald Knuth of Stanford University; the current version is still essentially similar to the 1983 version!

TeX has a horrible syntax and funky limitations, but there are so many available packages for it (such as LaTeX and the associated packages) as well as external applications (BibTeX) and tons of mathematical files made for it that it just cannot be replaced.

Some crazy people even use TeX to
typeset a newspaper and a personnel directory.

Good static analysis techniques would allow this optimization. What's implement in the .net runtime sounds pretty much syntactic; there are semantical methods that are more powerful.

Advanced compilers for FORTRAN/C/C++ often do more complex optimizations such as software pipelining, vectorization and loop movements.

The trust you should have in the compiler depends on how the analysis method is constructed. I don't have too much trust in analysis methods based on recognizing "loose patterns" in code, because they may end up recognizing as optimizable code that should not be optimized away. Semantic method are more robust. Also, such methods can be tested by looking at the results of the analyses, not just the optimization. For instance, in your case, the method would have PROVED that the constraint i

Static analysis method are now used for far more complex tasks, such as proving that a 70000-line C program never accesses arrays out of bounds or encounters arithmetic overflows in any operating context.

I agree with the safer programming languages (such as Java or OCaml). I agree with the better tools. I agree with dynamic checks, stack guards and whatever. Let's add for good measure static analysis.

But why UML? UML is a modeling language. What the above solutions are trying to catch are implementation issues.

If you're trying to catch issues at the design level, you need much more than a modeling language in which to write vague descriptions. You need tools that can show that your implementation corresponds to the design. You need tools that are capable of dealing with issues such as interlocking threads.

The classes of the Java standard library are, by default, thread-safe. This means that all methods that could cause race conditions are synchronized. Unfortunately, unneeded synchronizations are a major performance hit (it depends on the thread implementation).

So, whether you write s1 + s2 + s3 or rewrite this expression using a StringBuffer (which is, anyway, what the compiler does), you incur on most implementations a performance hit because the StringBuffer will be treated as if it could be shared between several threads.

Now, in this case, it would be sufficient to have a StringBuffer_unsynchronized class. In more complex cases, you would like to compile all methods with or without synchronization and have a system automatically switch to unsynchronized methods if it is safe to do so.

Unfortunately, telling whether it is safe to use unsynchronized methods is non trivial. Essentially, you have to know whether your objects may escape to other threads. Of course, as any nontrivial semantic properties, this is undecidable (which means there's no generic algorithm always giving the right answer to the question in finite time). There are whole doctorate theses written on such topics!

"I think the real question isn't "is this for real?" but rather "why, God why?""

That's pretty much the question I was asking myself after reading this page on Unlambda.

Sure, no one is going to ever read, let alone debug a Whitespace or Unlambda program's source code, but typing the source code in the first place is a bit harder in the case of Unlambda (only functions, no variables, a number of built-in functions which are used to create other functions which ultimately do the stuff you wanted to do).