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Earth

Planned Nuclear Reactors Will Destroy Atomic Waste 344

Posted by Soulskill
from the but-where-will-we-get-our-superheroes dept.
separsons writes "A group of French scientists are developing a nuclear reactor that burns up actinides — highly radioactive uranium isotopes. They estimate that 'the volume of high-level nuclear waste produced by all of France’s 58 reactors over the past 40 years could fit in one Olympic-size swimming pool.' And they're not the only ones trying to eliminate atomic waste: Researchers at the University of Texas in Austin are working on a fusion-fission reactor. The reactor destroys waste by firing streams of neutrons at it, reducing atomic waste by up to 99 percent!"

Comment: Re:Godel's Incompleteness Theorem? (Score 1) 517

by yoris (#29053295) Attached to: World's First Formally-Proven OS Kernel
Hey, as a once (medium long ago) CS major myself, I'd like to comment on your question. I think you're not really referring to Godel's Incompleteness Theorem, which relates more to axiomatic systems then it does to computer programs / algorithms, but to Turing's proof that the halting problem is algorithmically undecidable. The halting problem here is the problem of deciding whether a certain algorithm will run forever or ever halt. Algorithmically undecidable here means that it is impossible for you to build an algorithm such that for any given input program P, your algorithm will say whether or not the program P will ever halt. Important remark: this does not mean that it is impossible for you to prove that a specific program P1 halts or doesn't halt. It just means that it is impossible to write down an algorithm for doing it in all cases. It is even impossible to decide for which cases it is possible and for which not.

A consequence (or more generalized version if you will) of the fact that the halting problem is algorithmically undecidable is that the static analysis problem is also algorithmically undecidable. Static analysis here is the task of deciding whether a program P satisifies a specification S. You can not write an algorithm such that for any combination (S,P) the algorithm will tell you whether the program satisfies the spec or not. That again does not mean that it is impossible to prove that an individual program P1 satisfies an individual specification S1, which appears to be the case here.

To quote wikipedia on the halting problem:
http://en.wikipedia.org/wiki/Halting_problem
While Turing's proof shows that there can be no general method or algorithm to determine whether algorithms halt, individual instances of that problem may very well be susceptible to attack. Given a specific algorithm, one can often show that it must halt for any input, and in fact computer scientists often do just that as part of a correctness proof. But each proof has to be developed specifically for the algorithm at hand; there is no mechanical, general way to determine whether algorithms on a Turing machine halt. However, there are some heuristics that can be used in an automated fashion to attempt to construct a proof, which succeed frequently on typical programs. This field of research is known as automated termination analysis.

Comment: Re:Rewarding incompetence (Score 1) 179

by yoris (#28780391) Attached to: Adobe Chided For Insecure Acrobat Reader

It says a lot about the world that no other nation yet has the 1st and 2nd amendment.

Just out of curiosity, is this supposed to say something about the US or about the rest of the world? In the latter case, what exactly is the fact that the other democracies of the world did not choose to make the right to keep firearms in the house a constitutional right supposed to say about them?

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