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Luís F. Simões

Polynomial Time Code For 3-SAT Released, P==NP - Slashdot - 0 views

science.slashdot.org/...me-Code-For-3-SAT-Released-PNP

INF computer science mathematics algorithm complexity P=NP?

shared by Luís F. Simões on 20 Jan 11 - No Cached
  • "Vladimir Romanov has released what he claims is a polynomial-time algorithm for solving 3-SAT. Because 3-SAT is NP-complete, this would imply that P==NP. While there's still good reason to be skeptical that this is, in fact, true, he's made source code available and appears decidedly more serious than most of the people attempting to prove that P==NP or P!=NP. Even though this is probably wrong, just based on the sheer number of prior failures, it seems more likely to lead to new discoveries than most. Note that there are already algorithms to solve 3-SAT, including one that runs in time (4/3)^n and succeeds with high probability. Incidentally, this wouldn't necessarily imply that encryption is worthless: it may still be too slow to be practical."
  • Luís F. Simões on 20 Jan 11
     
    here we go again...
  • Luís F. Simões on 28 Feb 11
     
    slashdot: "Russian computer scientist Vladimir Romanov has conceded that his previously published solution to the '3 SAT' problem of boolean algebra does not work."
Joris _

What the strange persistence of rockets can teach us about innovation. - 5 views

www.slate.com/...all

technology innovation space politic MAD

shared by Joris _ on 04 Feb 11 - No Cached
  • Joris _ on 04 Feb 11
     
    If I could write, this is exactly what I would write about rocket, GO, and so on... :) "we are decadent and tired. But none of the bright young up-and-coming economies seem to be interested in anything besides aping what the United States and the USSR did years ago. We may, in other words, need to look beyond strictly U.S.-centric explanations for such failures of imagination and initiative. ... Those are places we need to go if we are not to end up as the Ottoman Empire of the 21st century, and yet in spite of all of the lip service that is paid to innovation in such areas, it frequently seems as though we are trapped in a collective stasis." "But those who do concern themselves with the formal regulation of "technology" might wish to worry less about possible negative effects of innovation and more about the damage being done to our environment and our prosperity by the mid-20th-century technologies that no sane and responsible person would propose today, but in which we remain trapped by mysterious and ineffable forces."
  • ...4 more comments...
  • Ma Ru on 04 Feb 11
     
    Very interesting, though I'm amused how the author tends to (subconsciously?) shift the blame to non-US dictators :-) Suggestion that in absence of cold war US might have abandoned HB and ICBM programmes is ridiculous.
  • Luís F. Simões on 04 Feb 11
     
    Interesting, this was written by Neal Stephenson ( http://en.wikipedia.org/wiki/Neal_Stephenson#Works ). Great article indeed. The videos of the event from which this arose might be equally interesting: Here Be Dragons: Governing a Technologically Uncertain Future http://newamerica.net/events/2011/here_be_dragons "To employ a commonly used metaphor, our current proficiency in rocket-building is the result of a hill-climbing approach; we started at one place on the technological landscape-which must be considered a random pick, given that it was chosen for dubious reasons by a maniac-and climbed the hill from there, looking for small steps that could be taken to increase the size and efficiency of the device."
  • Joris _ on 04 Feb 11
     
    You know Luis, when I read this quote, I could help thinking about GO, which would be kind of ironic considering the context but not far from what happens in the field :p
  • LeopoldS on 05 Feb 11
     
    Fantastic!!!
  • LeopoldS on 05 Feb 11
     
    Would have been nice if it were historically more accurate and less polemic / superficial
  • pacome delva on 14 Feb 11
     
    mmmh... the wheel is also an old invention... there is an idea behind but this article is not very deepfull, and I really don't think the problem is with innovation and lack of creative young people !!! look at what is done in the financial sector...
Luís F. Simões

Pattern | CLiPS - 2 views

www.clips.ua.ac.be/pattern

AI language text data mining web Python

shared by Luís F. Simões on 02 Mar 11 - No Cached
  • Pattern is a web mining module for the Python programming language. It bundles tools for data retrieval (Google + Twitter + Wikipedia API, web spider, HTML DOM parser), text analysis (rule-based shallow parser, WordNet interface, syntactical + semantical n-gram search algorithm, tf-idf + cosine similarity + LSA metrics) and data visualization (graph networks).
  • Luís F. Simões on 02 Mar 11
     
    Intuitive, well documented, and very powerful. A library to keep an eye on. Check the example Belgian elections, June 13, 2010 - Twitter opinion mining
ESA ACT

Wikipedia founder plans open-source search engine - 0 views

www.newscientisttech.com/article.ns

wiki websearch open-source

shared by ESA ACT on 24 Apr 09 - No Cached
  • ESA ACT on 24 Apr 09
     
    New YGT project, Grub and Lucene for ESA.
Ma Ru

Dark Matter or Black Hole Propulsion? - 1 views

www.newscientist.com/...s-for-interstellar-travel.html

NRG propulsion star travel space PHY

shared by Ma Ru on 25 Nov 09 - Cached
  • Ma Ru on 25 Nov 09
     
    Anyone out there still doing propulsion stuff? Two more papers just waiting to get busted... http://arxiv.org/abs/0908.1429v1 http://arxiv.org/abs/0908.1803
  • ...5 more comments...
  • Luzi Bergamin on 26 Nov 09
     
    What an awful bunch of complete nonsense!!! But I don't think anybody wants to hear MY opinion on this...
  • pacome delva on 26 Nov 09
     
    wow, is this serious at all...!?
  • Luzi Bergamin on 26 Nov 09
     
    Are you joking?? The BH drive propses a BH with a lifetime of about an year, just 10^7 tons, peanuts!! Then you have to produce it, better not on Earth, so you do this in space, with a laser that produces an equivalent of 10^9 tons highly foucussed, even more peanuts!! Reasonable losses in the production process (probably 99,999%) are not yet taken into account. Engineering problems... :-) The DM drive is even better, they want to collect DM and compress it in a propulsion chamber. Very easy to collect and compress a gas of particles that traverse the Earth without any interaction. Perhaps if the walls of the chamber are made of artificial BHs?? Who knows??
  • LeopoldS on 26 Nov 09
     
    WRONG!!! we are all just WAITING for your opinion on this ....!!!
  • pacome delva on 27 Nov 09
     
    well, yes my remark was ironic... I'm surprised they did a magazine on these concepts...! But the press is always waiting for sensational. They do not even wait for the work to be peer-reviewed now to make an article on it ! This is one of the bad sides of arxiv in my opinion. It's like a journalist that make an article with a copy-paste in wikipedia ! Anyway, this is of course complete bullsh..., and I would have laughed if I had read this in a sci-fi book... but in a "serious" article i'm crying... For the DM i do not agree with your remark Luzi. It's not dark energy they want to use. The DM is baryonic, it's dark just because it's cold so we don't see it by usual means. If you believe the in the standard model of cosmology, then the DM should be somewhere around the galaxies. But it's of course not uniformly distributed, so a DM engine would work (if at all...) only in the periphery of galaxies. It's already impossible to get there...
  • Luzi Bergamin on 27 Nov 09
     
    One reply to Pacome, though the discussion exceeds by far the relevance of the topic already. Baryonic DM is strictly limited by cosomology, if one believes in these models, of course. Anyway, even though most DM is cold, we are constantly bombarded by some DM particles that come together with cosmic radiation, solar wind etc. etc. If DM easily interacted with normal matter, we would have found it long ago. In the paper they consider DM as neutralinos, which are neither baryonic nor strongly or electromagnetically interacting.
  • pacome delva on 27 Nov 09
     
    well then I agree, how the fu.. they want to collect them !!!
Luís F. Simões

Ralph Langner: Cracking Stuxnet, a 21st-century cyber weapon | Video on TED.com - 2 views

www.ted.com/..._21st_century_cyberweapon.html

INF cyberwarfare TED

shared by Luís F. Simões on 04 Apr 11 - No Cached
LeopoldS liked it
  • When first discovered in 2010, the Stuxnet computer worm posed a baffling puzzle. Beyond its unusually high level of sophistication loomed a more troubling mystery: its purpose. Ralph Langner and team helped crack the code that revealed this digital warhead's final target -- and its covert origins. In a fascinating look inside cyber-forensics, he explains how.
johannessimon81

42 - a constant of nature - 3 views

en.wikipedia.org/...Gravity_train

science fun

shared by johannessimon81 on 29 Dec 13 - No Cached
  • johannessimon81 on 29 Dec 13
     
    It turns out that falling along any straight line through the Earth takes 42 minutes (Gravity train). I think this has not been opted as an explanation of Douglas Adams' 42 but this fact is definitely quite beautiful.
jcunha

Missing link in metal physics explains Earth's magnetic field - 0 views

phys.org/...al-physics-earth-magnetic.html

PHY science

shared by jcunha on 29 Jan 15 - No Cached
  • jcunha on 29 Jan 15
     
    In a work published on Nature (http://www.nature.com/nature/journal/v517/n7536/full/nature14090.html#affil-auth) a new DFT based simulation of convection in Earth's Core iron shows that electron-electron scattering has a similar contribution to electron's thermal vibration. The outcome is that using the old dynamo theory the simulation matches the Earth magnetic field experimental results, solving an 80 years old puzzle.
  • Thijs Versloot on 29 Jan 15
     
    Yay to science! I'm always intrigued by related experiments that try to measure material properties at the GPa range. Especially, the efforts of reaching 'metallic hydrogen' (http://en.wikipedia.org/wiki/Metallic_hydrogen), requiring pressures above 25GPa at which hydrogen becomes conductive. It is thought that gas giant planets could have such a core, but no-one has been able to produce/verify this theory as off yet.
jaihobah

Demonstrating a new technology for space debris removal using a bi-directional plasma t... - 2 views

www.nature.com/...s41598-018-32697-4

space PHY

shared by jaihobah on 01 Oct 18 - No Cached
  • jaihobah on 01 Oct 18
     
    Some people answering the question 'What's cooler than blasting space debris with lasers...?'.
  • Marcus Maertens on 03 Oct 18
     
    If it fires in both directions, can we align it such that it deorbits two debris with one shot?
  • Dario Izzo on 05 Oct 18
     
    :) the idea of having this method for debris removal is actually an ACT one from Claudio Bombardelli (ACT RF in MAD https://en.wikipedia.org/wiki/Ion-beam_shepherd). This is just a technological device to implement it so that the system on board is simplified (i.e. instead of two engines, you get away with one and a weird nozzle) Marcus, you cannot align it to get rid of two debris as you need to keep the spacecraft close to the debris as this is a long duration acion. One of the two would drift away (can only follow one!)
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