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I'll believe this when these superconducting pigs levitate above magnets.

Oh, but they already do! Unfortunately, with pigs being so intelligent, they seem to have a real phobia about being that close to liquid nitrogen. We have tried professional counselors, but we just can't seem to get them into the tube with that stuff. Who would have thought?

Examples of diamagnetic levitation:
https://www.ru.nl/hfml/researc...

With a switchable magnet orders of magnitude stronger, you should be able to heat the hydrogen atoms directly, should you not? Here's a pic of a live frog levitating in a 16 Tesla magnetic field.
http://www.ru.nl/hfml/research...

Blame the university's press department, as always. There's quite a jump in hyperbole between the Ange and Nature Chem's comments, versus the press release. Why do journalists even read university press releases any more? You know they're going to be misleading.

There's a field called Grammar Induction, and the problem of learning regular languages, aka regular inference, can be considered a subfield. People have been working on this since the '50s. Applications include learning DTDs for XML/wrapper induction, and all kinds of problems in bioinformatics and natural language processing.

There's a strong link with the graph coloring problem, see
http://www.cs.ru.nl/~sicco/papers/alt12.pdf

In this field, the focus is generally on learning FSAs, but these can easily be transformed into regexps. There's work on learning regexps directly, see
http://www.informatik.uni-trier.de/~fernau/papers/Fer05c.pdf

Enjoy.

http://www.telegraaf.nl/binnenland/21769604/__NL_se_vinding_geblokkeerd__.html

Form the University site: http://www.ru.nl/english/general/news_agenda/news/@895890/radboud-university-0/

Interesting is the statement VW was informed about the problem nine months ago and Dutch Government/Jurisprudence finds 6 months of silence already sufficient.

Frogs have been levitated in a 10T field. Would these machines levitate humans? Or would there be problems from the machine focusing on one part of the body?

Here's a link that talks about the energy field surrounding matter.

http://www.ru.nl/hfml/research/levitation/diamagnetic/

Incidentally, it's the same URL as the one in the summary.

well this frog doesn't seem to be falling!

Look for The Flying DutchFrog to see electromagnet experiments in levitation on other vertebrates.

ProofWeb http://proofweb.cs.ru.nl/ is an IDE-like system for teaching logic and formalized proofs through the web. It was designed for teaching logic to undergrad CS students, but it's been successfully used to teach proof assistant courses.

While ProofWeb's database is limited to simple logic exercises, it is actually based on the Coq proof assistant http://coq.inria.fr/, which can be used to develop software in an interactive way and even certify that it meets a formal specification. (It uses a functional programming language, similar to Haskell or ML.) My guess is that an extended version of this system could be very useful in CS and software engineering.

It's like trying to describe to someone a book by describing which pixels are black and white on the page.

Very good analogy, thank you. This is what someone who knows only about printing press would say about impossibility of showing text on a computer screen - "imagine the work that would have to be done to split the image into pixels and then put them together so that they don't look like gibberish".

Formal proofs are (...) nowhere near able to handle genuine problems in mathematics.

If you really want you can always make this statement true by selecting the right definition of "genuine problems", for example defining genuine problems as those that have not been formalized yet. Otherwise you may want to check the list of top 100 of mathematical theorems to see which ones have proofs written in a formal proof language.

Unreadable by humans: there's no point.

Here you have a point. This proof is not designed to explain to a human why the theorem is true. It should not be called a proof, it should be called a verification script. But this is just an unfortunate choice of the language. There are other proof languages that are designed to be readable by humans.

I can give a concrete answer. Browse metamath.org, a similar project in which machine verified proofs are collected. Look at the vast amount of work required to prove even the most trivial things. ... Converting real world mathematics into machine readable form is a vast endeavor. It's also something that doesn't interest mathematicians, so the collection of machine verifiable proofs will lag *centuries* behind the state of the art.

This is probably correct if you're talking about minimalistic systems like Metamath or Russell & Whitehead's Principia.

What such projects are attempting is like trying to build a concrete building by gluing grains of sand together by hand, or writing a complete Linux distro in assembly code. The result does not prove that the ideas of building from concrete or writing software are a failure, only that you need the right tools to do that.

There is an interesting note by Freek Wiedijk which estimates the effort required for a "standard library" of formalized mathematics as about 140 man-years.

This assumes a "de Bruijn factor" of about 4 (i.e. one page of informal mathematics translates into four pages of formalized language) and a cost of ~2 man-days per page of formal mathematics. Both of these will undoubtedly be improved by further research.

Perhaps we shouldn't worry about this, though. To many people, doing formalized mathematics is as fun as writing computer code; why should we worry that the supply of that fun is near-limitless?

it doesnt take an expert to know that running a substance with no magnetic properties past a magnetic feild has absolutely zero effect.

Quick! Define "no magnetic properties"!

can be found here

Which is NOT to say that any arbitrary magic is indistinguishable from advanced technology. Things that violate well-understood laws of physics without exploiting little-understood loopholes are "magic" that can't be imitated by technology however advanced.

Sure they can, or at least appear to. You simply have to add variables to the system which the audience doesn't know about. For example, see diamagnetic levitation. And don't forget to read a this response to really drive the point home :).

That's what the saying really means: if you are more knowledgeable than your audience, you can always fool them into thinking that you can violate the laws of physics, that is, do magic. It doesn't matter if the audience is cavemen, Greek philosophers or modern-day scientists; as long as you know more than they do, you can hide your deception in that gap - assuming, of course, that the gap is big enough.

And please understand that knowing basic physics, even perfectly, does not protect against this perfectly, because it doesn't necessarily mean that you can figure out all possible consequences and applications of those laws.

Which is NOT to say that any arbitrary magic is indistinguishable from advanced technology. Things that violate well-understood laws of physics without exploiting little-understood loopholes are "magic" that can't be imitated by technology however advanced.

Sure they can, or at least appear to. You simply have to add variables to the system which the audience doesn't know about. For example, see diamagnetic levitation. And don't forget to read a this response to really drive the point home :).

That's what the saying really means: if you are more knowledgeable than your audience, you can always fool them into thinking that you can violate the laws of physics, that is, do magic. It doesn't matter if the audience is cavemen, Greek philosophers or modern-day scientists; as long as you know more than they do, you can hide your deception in that gap - assuming, of course, that the gap is big enough.

And please understand that knowing basic physics, even perfectly, does not protect against this perfectly, because it doesn't necessarily mean that you can figure out all possible consequences and applications of those laws.

I'm not a physicist, but I'm still fascinated by astronomical phenomena like this. Can anyone tell me what the effects of ultra-strong magnetic fields would be on a living creature? I know we can levitate frogs with powerful magnets, but nothing strange happens to the frog itself. Can we withstand a magnetic field of any strength?

You can levitate frogs and such by themselves, without having to support them on a levitating magnet -- see the Youtube video. Of course, that technique doesn't work with superconductors -- the field strength required is higher than they can sustain. Instead, you need a 6 megawatt electromagnet.

I suppose 6 MW to levitate a frog is about as impractical as it gets...

Have a look at Clean (http://clean.cs.ru.nl/) for a use of pointers (internally) that makes for efficient execution. An interesting read concerning the subject is found here:

http://clean.cs.ru.nl/contents/Addison__Wesley_book/addison__wesley_book.html

Actual benchmarks to show the efficiency can be examined here (note the comparison is with C-versions of the same algorithms compiled on gcc):

http://shootout.alioth.debian.org/gp4/benchmark.php?test=all&lang=clean&lang2=gcc

Here's Java 6 (server version) for comparison:

http://shootout.alioth.debian.org/gp4/benchmark.php?test=all&lang=java&lang2=gcc

You'll notice that differences are mainly in the memory footprint, already known to be attributable to the large number of libraries (classes) loaded into the vm at start-up, something the Clean runtime isn't quite as encumbered with:

(Java) http://java.sun.com/docs/books/performance/1st_edition/html/JPRAMFootprint.fm.html

So, the difference in speed is often-times negligible, and it's been shown that the memory footprint can be reduced to a size where you can run an embedded jvm in a mobile phone (really!), and rumour has it that someone even wrote an operating system in Java, but the memory footprint still seems the biggest culprit:

http://www.jnode.org/node/573

In other words, it's not Java - the language, but Java - the massive OO-framework, and JVM - the specific implementation, that's the problem. Even C++ or C with an OO-framework can be made into a large memory footprint, if you can believe it:

http://www.microsoft.com/windows/products/windowsvista/editions/systemrequirements.mspx

Then, of course, memory is cheap:

http://www.simmtester.com/page/memory/memprice.asp

But, the over-use of which, sometimes stays with us as itching bugs for too long:

http://blog.wired.com/monkeybites/2007/11/firefox-3-add-o.html

If memory serves me right (http://www.google.com), there's something to be said of the virtues of garbage-collection applied to systems programming:

http://www.digitalmars.com/d/

and the actual (memory and) time efficiency of such an attempt:

http://shootout.alioth.debian.org/gp4/d.php

But I could be wrong. After all, no-one in their right mind would ever attempt to write an operating system in something like, say, Lisp:

http://cbbrowne.com/info/lisposes.html

- let alone design an actual computer around it:

http://en.wikipedia.org/wiki/Lisp_machine

It simply wouldn't run. No, the skills of an engineer depend solely on the language he/she speaks, not on the abstract concepts he/she masters, applied to whatever tool he/she chooses to use/create.

That is why I propose we all forget about abstraction all-together, and revert to coding like this:

010101100001111010110101101101111101111...

But wait, that is itself an abstraction - Turing must have suffered from premature abstraculation. No, let's hear it for using copperwires instead of silicon, so we can attach some large, hand-

Besides this article being a duplicate I have some serious doubts whether the authors of SAGE have researched existing math software as serious as they should have.

The entire site is showing a weird perspective on the respectable and established science of automated proofs. Admittedly, demanding that automated proofs are both open-sourced and based on open-source programs is a good approach. But the list of programs mentioned there (Python, GAP, Singular, PARI, Maxima, SciPy, SAGE) does not thrill those who are serious about computer-assisted proofs. It must be said that the well-known commercial programs like Mathematica, Maple, Magma, etc. are equally unsuited for trustworthy proofs.

The reason is that all these systems are way too bloated and lack an axiomatic approach. Their intent is to manipulate symbolic terms easily. As such, they are good for assisting a mathematician proofing theorems or checking a proof. But there is another kind of systems that is being used for formalizing and verifying mathematical proofs on the computer. The intent is to define a set of axioms using a tiny engine, and from there derive small theorems, more theorems, and so on, until the final theorem has been proofed. The idea is that the system's kernel is so tiny it can be fully comprehended by individual mathematicians. If the proof can be constructed from a few sane axioms and runs through the computer, voila, that's a proof by computer. Freek Wiediejk has assembled a list of 100 famous theorems and their poofs. I am not able to find any of the systems in this list on the SAGE site. Why not? Are the authors really unaware of those systems? Aren't most (all?) of them open-source, too?

Any serious mathematician will not accept a proof carried out by Maxima or Maple, and having a system like SAGE that acts like a frontend to these is of no help at all. Besides, we already have Texmacs.

Python is not part of the answer. Neither are Ruby, Lisp, ...

The problem of trusting a proof by computer is that the languages listed above are too big to be trusted. But that problem has been solved by building engines that are so small that people can fully comprehend them. Then, the engine can be extended by proving theorems using selected fundamental axioms. Combining such proven theorems to derive new theorems is what constitutes a proof.

Here is a list of 100 mathematical theorems and a list of systems used to proof them: http://www.cs.ru.nl/~freek/100/. Mathematicians are taking systems like Coq, HOL, Mizar etc. serious but proofs in Mathematica or Python are not acceptable.

Of course, those systems are written in general purpose computer languages, too. For instance, HOL light is written in OCaml. Errors introduced by the underlying language must be excluded by running the system on different implementations, different hardware, etc. But many mathematicians believe that being too paranoid about a minimal proof assistant is fruitless and only leads to the descend into a fundamentalist death spiral.

In what part of the world do people typically levitate frogs?

Nah, in fact scientists have made a frog levitate with a 16T magnetic field with no ill affects!

It would just make us start floating I assume, atleast they were able to let a number of things float because of an intense magnetic field over here: http://www.hfml.ru.nl/froglev.html

You can also suspend a frog in a strong magnetic field because water is diamagnetic. http://www.hfml.ru.nl/froglev.html

They have magnetic levitation for fish and frogs.

That's why C is reaching its limit. Things like Erlang and Clean, as well as parallizing Lisp compilers will become more widely used to handle these multiprocessing systems.

There are a lot of metal ions in your body...sodium, potassium, calcium. Those are all metal ions, and their movement through ion channels is what underlies mental activity, including your perception of feeling anything. Cognitive effects of exposure to extremely strong magnetic fields (as in TMS or extremely strong MR scanners) are most likely due to effects on movements of those ions, while dizziness from the "weak" magnetic fields of fMRI is mediated by effects on mineral crystals in the inner ear. In no case is the effect on water likely to be directly involved. That said, I wouldn't want to put my head in there.

Surprisingly, you can do that! http://www.hfml.ru.nl/froglev.html

Nifty. Here's someone using graphviz for a similar situation - dependencies for apps in the FreeBSD ports system.

Oh, please, NIB magnets are strong, but they're not that strong. This is the kind of magnet that sucks in steel utensils from 20 feet away. I've got a dozen 1" cube N45s myself; Combined, they'll pull in metal from about 8 inches away. Mod -1, factually incorrect.

It's not clear that it's relevant to the experiment described in the article but magnetic levitation is already possible.

A colleague of mine (we work at the FC Donders Centre for Cognitive Neuroimaging, http://www.ru.nl/fcdonders), told me that the anterior cingulate (which is found in these trials), is involved in sensosomatory processes, such as respiration, heart beats, skin sensitiviy... That means that seeing activation there in an fMRI scan is exactly the same as finding a difference in heart rate, respiratory rate or skin resistance, except it is much more expensive.

After an inmense prestation the spaceship was drawn in hyperspace. No distance was actually coverd in this first experiment, but everyone wonderd why the spaceship came back with a frog on board. Could it be that the magnetic hyperspace is actually occupied by Frogs?

8)

I believe the frog levitated due to the paramagnetic effects of water under an extremely intense magnetic field. The frog was not sitting on a metal plate that was subsequently levitated... it was floating all by its lonesome.

And yes, the frog was perfectly fine after the experience.

Looka here: http://www.hfml.ru.nl/froglev.html

I think you're referring to a Bitter magnet. There's a video of it and the frog at that link. Check out the rest of the site too.

http://www.hfml.ru.nl/levitation-movies.html

Not over, but inside of. Each atom of the frog is levitated individually. Here's a link to the movies of this:
http://www.hfml.ru.nl/froglev.html

Even if I'm off by many orders of magnitude (IANAP), the required field strength will be unattainably high.

http://slashdot.org/comments.pl?sid=61228&threshol d=1&commentsort=0&tid=131&mode=thread&cid=5758997
http://freetype.sourceforge.net/patents.html

http://en.tldp.org/HOWTO/FDU/truetype.html

http://www.niii.ru.nl/~pauldv/fonts.php

http://www.linuxquestions.org/questions/showthread .php?s=&threadid=257705

Does this help? Basically the 2 issues are hints embedded within a font for optimal viewing, and the second have to do with freetype fonts which modern oses use over ttfonts. The Linux version is not feature complete due to the legal mess. I am sure you can download the patented versions and install it yourself but its a pain.

This system has since been open sourced under the GPL license and my new research group here at University College Dublin is working on completing, documenting, evaluating, and formally specifying the system.

I led the evaluation of this system's external network security for the Dutch government while at the SoS Group at Radbound University Nijmegen.

I was also the co-author of the vote tally application for the European Elections in Holland. That application was written in less than eight weeks using formal methods to ensure that the software of extremely high quality and indeed every vote was counted. This system was written in Java with JML annotations and was partially statically checked (verified) with ESC/Java2.

See the paper "Electronic and Internet Voting in The Netherlands for more high-level information.

This system has since been open sourced under the GPL license and my new research group here at University College Dublin is working on completing, documenting, evaluating, and formally specifying the system.

I led the evaluation of this system's external network security for the Dutch government while at the SoS Group at Radbound University Nijmegen.

I was also the co-author of the vote tally application for the European Elections in Holland. That application was written in less than eight weeks using formal methods to ensure that the software of extremely high quality and indeed every vote was counted. This system was written in Java with JML annotations and was partially statically checked (verified) with ESC/Java2.

See the paper "Electronic and Internet Voting in The Netherlands for more high-level information.

This system has since been open sourced under the GPL license and my new research group here at University College Dublin is working on completing, documenting, evaluating, and formally specifying the system.

I led the evaluation of this system's external network security for the Dutch government while at the SoS Group at Radbound University Nijmegen.

I was also the co-author of the vote tally application for the European Elections in Holland. That application was written in less than eight weeks using formal methods to ensure that the software of extremely high quality and indeed every vote was counted. This system was written in Java with JML annotations and was partially statically checked (verified) with ESC/Java2.

See the paper "Electronic and Internet Voting in The Netherlands for more high-level information.