Skip to main content

Home/ Advanced Concepts Team/ Group items matching "complexity" in title, tags, annotations or url

Group items matching
in title, tags, annotations or url

Sort By: Relevance | Date Filter: All | Bookmarks | Topics Simple Middle
3More

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."
1More

Behavioural Economics? Try Biological Economics - 2 views

ipezone.blogspot.com/...-economics-try-biological.html science fun
shared by Loretta Latronico Poulain on 08 Mar 11 - No Cached
  • Luís F. Simões on 08 Mar 11
     
    The "Biological Economics" thing is a hyping (or misunderstanding) of the BBC article. The work it refers to seems to be an application of Complex Networks theory to financial networks. I found what appear to be some of the related publications: Andrew G. Haldane (April 2009) Rethinking the financial network (further references in the footnote to page 10) Erlend Nier, Jing Yang, Tanju Yorulmazer and Amadeo Alentorn (April 2008) Network models and financial stability Funny how these issues have been repeatedly popping up at the ACT in recent weeks. This connects both with the discussions on information spreading in networks, and with roadmaps' robustness.
10More

Shell energy scenarios to 2050 - 6 views

www.shell.com/...shell_energy_scenarios_2050 energy future forecast politics economy climate_change
shared by Luís F. Simões on 09 Mar 11 - No Cached
  • Luís F. Simões on 09 Mar 11
     
    just in case you were feeling happy and optimistic
  • ...7 more comments...
  • Francesco Biscani on 09 Mar 11
     
    An energy scenario published by an oil company? Allow me to be sceptical...
  • Joris _ on 10 Mar 11
     
    Indeed, Shell is an energy company, not just oil, for some time now ... The two scenarii are, in their approach, dependant of economic and political situation, which is right now impossible to forecast. Reference to Kyoto is surprising, almost out-dated! But overall, I find it rather optimistic at some stages, and probably the timeline (p37-39) is unlikely with recent events.
  • Luís F. Simões on 10 Mar 11
     
    the report was published in 2008, which explains the reference to Kyoto, as the follow-up to it was much more uncertain at that point. The Blueprint scenario is indeed optimistic, but also quite unlikely I'd say. I don't see humanity suddenly becoming so wise and coordinated. Sadly, I see something closer to the Scramble scenario as much more likely to occur.
  • LeopoldS on 12 Mar 11
     
    not an oil company??? please have a look at the percentage of their revenues coming from oil and gas and then compare this with all their other energy activities together and you will see very quickly that it is only window dressing ... they are an oil and gas company ... and nothing more
  • Joris _ on 14 Mar 11
     
    not JUST oil. From a description: "Shell is a global group of energy and petrochemical companies." Of course revenues coming from oil are the biggest, the investment turnover on other energy sources is small for now. Knowing that most of their revenues is from an expendable source, to guarantee their future, they invest elsewhere. They have invested >1b$ in renewable energy, including biofuels. They had the largest wind power business among so-called "oil" companies. Oil only defines what they do "best". As a comparison, some time ago, Apple were selling only computers and now they sell phones. But I would not say Apple is just a phone company.
  • LeopoldS on 14 Mar 11
     
    window dressing only ... e.g. Net cash from operating activities (pre-tax) in 2008: 70 Billion$ net income in 2008: 26 Billion revenues in 2008: 88 Billion Their investments and revenues in renewables don't even show up in their annual financial reports since probably they are under the heading of "marketing" which is already 1.7 Billion $ ... this is what they report on their investments: Capital investment, portfolio actions and business development Capital investment in 2009 was $24 billion. This represents a 26% decrease from 2008, which included over $8 billion in acquisitions, primarily relating to Duvernay Oil Corp. Capital investment included exploration expenditure of $4.5 billion (2008: $11.0 billion). In Abu Dhabi, Shell signed an agreement with Abu Dhabi National Oil Company to extend the GASCO joint venture for a further 20 years. In Australia, Shell and its partners took the final investment decision (FID) for the Gorgon LNG project (Shell share 25%). Gorgon will supply global gas markets to at least 2050, with a capacity of 15 million tonnes (100% basis) of LNG per year and a major carbon capture and storage scheme. Shell has announced a front-end engineering and design study for a floating LNG (FLNG) project, with the potential to deploy these facilities at the Prelude offshore gas discovery in Australia (Shell share 100%). In Australia, Shell confirmed that it has accepted Woodside Petroleum Ltd.'s entitlement offer of new shares at a total cost of $0.8 billion, maintaining its 34.27% share in the company; $0.4 billion was paid in 2009 with the remainder paid in 2010. In Bolivia and Brazil, Shell sold its share in a gas pipeline and in a thermoelectric power plant and its related assets for a total of around $100 million. In Canada, the Government of Alberta and the national government jointly announced their intent to contribute $0.8 billion of funding towards the Quest carbon capture and sequestration project. Quest, which is at the f
  • Joris _ on 14 Mar 11
     
    thanks for the info :) They still have their 50% share in the wind farm in Noordzee (you can see it from ESTEC on a clear day). Look for Shell International Renewables, other subsidiaries and joint-ventures. I guess, the report is about the oil branch. http://sustainabilityreport.shell.com/2009/servicepages/downloads/files/all_shell_sr09.pdf http://www.noordzeewind.nl/
  • LeopoldS on 16 Mar 11
     
    no - its about Shell globally - all Shell .. these participations are just peanuts please read the intro of the CEO in the pdf you linked to: he does not even mention renewables! their entire sustainability strategy is about oil and gas - just making it (look) nicer and environmentally friendlier
  • Joris _ on 16 Mar 11
     
    Fair enough, for me even peanuts are worthy and I am not able to judge. Not all big-profit companies, like Shell, are evil :( Look in the pdf what is in the upstream and downstream you mentionned above. Non-shell sources for examples and more objectivity: http://www.nuon.com/company/Innovative-projects/noordzeewind.jsp http://www.e-energymarket.com/news/single-news/article/ferrari-tops-bahrain-gp-using-shell-biofuel.html thanks.
7More

Prof. Markrams Hirnmaschine (Startseite, NZZ Online) - 2 views

www.nzz.ch/...s_hirnmaschine_1.10736223.html AI neuroscience SciFi
shared by Luzi Bergamin on 29 May 11 - No Cached
  • Luzi Bergamin on 29 May 11
     
    A critical view on Prof. Markram's Blue Brain project (in German).
  • ...4 more comments...
  • Luzi Bergamin on 29 May 11
     
    A critical view on Prof. Markram's Blue Brain project (in German).
  • LeopoldS on 30 May 11
     
    so critical that the comment needed to be posted twice :-) ?
  • Luzi Bergamin on 30 May 11
     
    Yes, I know; I still don't know how to deal with this f.... Diigo Toolbar! Shame on me!!!
  • dejanpetkow on 30 May 11
     
    Would be nice to read something about the modelling, but it appears that there is nothing published in detail. Following the article, the main approach is to model each(!) neuron taking into account the spatial structure of the neurons positions. Once achieved they expect intelligent behaviour. And they need a (type of) supercomputer which does not exist yet.
  • Ma Ru on 31 May 11
     
    As far as I know it's sort of like "Let's construct an enormous dynamical system and see what happens"... i.e. a waste of taxpayer's money... Able to heal Alzheimer... Yeah... Actually I was on the conference the author is mentioning (FET 2011) and I have seen the presentations of all 6 flagship proposals. Following that I had a discussion with one of my colleagues about the existence of limits of the amount of bullshit politicians are willing to buy from scientists. Will there be a point at which politicians, despite their total ignorance, will realise that scientists simply don't deliver anything they promise? How long will we (scientists) be stuck in the viscous circle of have-to-promise-more-than-predecessors in order to get money? Will we face a situation when we'll be forced to revert to promises which are realistic? To be honest none of the 6 presentations convinced me of their scientific merit (apart from the one on graphene where I have absolutely no expertise to tell). Apparently a huge amount of money is about to be wasted.
  • Luzi Bergamin on 01 Jun 11
     
    It's not just "Let's construct an enormous dynamical system and see what happens", it's worse! Also the simulation of the cosmological evolution is/was a little bit of this type, still the results are very interesting and useful. Why? Neither the whole cosmos nor the human brain at the level of single neurons can be modelled on a computer, that would last aeons on a "yet-to-be-invented-extra-super-computer". Thus one has to make assumptions and simplifications. In cosmology we have working theories of gravitation, thermodynamics, electrodynamics etc. at hand; starting from these theories we can make reasonable assumptions and (more or less) justified simplifications. The result is valuable since it provides insight into a complex system under given, explicit and understood assumptions. Nothing similar seems to exist in neuroscience. There is no theory of the human brain and apparently nobody has the slightest idea which simplifications can be made without harm. Of course, Mr. Markram remains completely unaffected of ''details'' like this. Finally, Marek, money is not wasted, we ''build networks of excellence'' and ''select the brightest of the brightest'' to make them study and work at our ''elite institutions'' :-). I lively remember the stage of one of these "bestofthebest" from Ivy League at the ACT...
6More

Bioinspired self-repairing slippery surfaces with pressure-stable omniphobicity : Natur... - 3 views

www.nature.com/...nature10447.html biomimetics plant self-repairing
shared by pandomilla on 22 Sep 11 - No Cached
LeopoldS liked it
  • a strategy to create self-healing, slippery liquid-infused porous surface(s) (SLIPS) with exceptional liquid- and ice-repellency, pressure stability and enhanced optical transparency. Our approach—inspired by Nepenthes pitcher plants13—is conceptually different from the lotus effect, because we use nano/microstructured substrates to lock in place the infused lubricating fluid. We define the requirements for which the lubricant forms a stable, defect-free and inert ‘slippery’ interface.
  • ts capability to repel various simple and complex liquids (water, hydrocarbons, crude oil and blood),
  • pandomilla on 22 Sep 11
     
    ...This slippery surface was bio-inspired by the carnivorous plant I showed you sometimes ago! I was sure it was a good idea! next time I will be quicker!!
  • ...1 more comment...
  • LeopoldS on 22 Sep 11
     
    Shit. I am sure that there is more to do on this. Let's have a closer look.
  • LeopoldS on 22 Sep 11
     
    And a good lesson that it is important to proceed quickly when you have an idea and don't wait ...
  • pandomilla on 23 Sep 11
     
    Yes, I will see what we could do, but they really did a good job, from the biomimetic of the surface, up to the realization of the material, and the tests...
3More

Academic publishers make Murdoch look like a socialist - 4 views

www.guardian.co.uk/...c-publishers-murdoch-socialist science
shared by Christos Ampatzis on 02 Sep 11 - No Cached
  • Christos Ampatzis on 02 Sep 11
     
    Who are the most ruthless capitalists in the western world? Whose monopolistic practices make Walmart look like a corner shop and Rupert Murdoch a socialist? You won't guess the answer in a month of Sundays. While there are plenty of candidates, my vote goes not to the banks, the oil companies or the health insurers, but - wait for it - to academic publishers.
  • LeopoldS on 11 Sep 11
     
    fully agree ... "But an analysis by Deutsche Bank reaches different conclusions. "We believe the publisher adds relatively little value to the publishing process … if the process really were as complex, costly and value-added as the publishers protest that it is, 40% margins wouldn't be available." Far from assisting the dissemination of research, the big publishers impede it, as their long turnaround times can delay the release of findings by a year or more." very nice also: "Government bodies, with a few exceptions, have failed to confront them. The National Institutes of Health in the US oblige anyone taking their grants to put their papers in an open-access archive. But Research Councils UK, whose statement on public access is a masterpiece of meaningless waffle, relies on "the assumption that publishers will maintain the spirit of their current policies". You bet they will. In the short term, governments should refer the academic publishers to their competition watchdogs, and insist that all papers arising from publicly funded research are placed in a free public database. In the longer term, they should work with researchers to cut out the middleman altogether, creating - along the lines proposed by Björn Brembs of Berlin's Freie Universität - a single global archive of academic literature and data. Peer-review would be overseen by an independent body. It could be funded by the library budgets which are currently being diverted into the hands of privateers. The knowledge monopoly is as unwarranted and anachronistic as the corn laws. Let's throw off these parasitic overlords and liberate the research that belongs to us."
  • Christos Ampatzis on 12 Sep 11
     
    It is a really great article and the first time I read something in this direction. FULLY AGREE as well. Problem is I have not much encouraging to report from the Brussels region...
1More

The evolving face of networks |Technology |The Guardian - 3 views

ow.ly/tjDS evolutionary graphs complex networks
shared by nikolas smyrlakis on 08 Oct 09 - Cached
  • nikolas smyrlakis on 08 Oct 09
     
    really really interesting article also referring to a Nature paper called Evolutionary dynamics on graphs
2More

Why three buses come at once, and how to avoid it - physics-math - 29 October 2009 - Ne... - 4 views

www.newscientist.com/...-once-and-how-to-avoid-it.html
shared by Francesco Biscani on 29 Oct 09 - Cached
  • Now systems complexity researchers Carlos Gershenson and Luis Pineda of the National Autonomous University of Mexico have devised a mathematical model that shows how the problem might be prevented
  • Francesco Biscani on 29 Oct 09
     
    This is from Carlos, the guy who gave a science coffee talk a couple of months ago.
2More

Bacterial computers can crack mathematical problems | Science | guardian.co.uk - 0 views

www.guardian.co.uk/...bacteria-computer inf computer science
shared by Francesco Biscani on 26 Jul 09 - Cached
LeopoldS liked it
  • Biologists have created a living computer from E. coli bacteria that can solve complex mathematical problems
  • LeopoldS on 26 Jul 09
     
    nice article ... though the colouring used seems a lit awkward to me ...
1More

SiG | Social Innovation Generation - 0 views

sigeneration.ca social innovation complexity
shared by nikolas smyrlakis on 11 Sep 09 - Cached
  • nikolas smyrlakis on 11 Sep 09
     
    How about that for an abstract discipline, and I thought CMS was abstract. Sounds great though: Social Innovation Generation: "Social innovation is an initiative, product, process or program that profoundly changes the basic routines, resource and authority flows or beliefs of any social system. Successful social innovations have durability and broad impact. While social innovation has recognizable stages and phases, achieving durability and scale is a dynamic process that requires both emergence of opportunity and deliberate agency, and a connection between the two."
2More

Access : Coherent emission of light by thermal sources : Nature - 0 views

www.nature.com/...416061a.html SPS NRG WPT
shared by LeopoldS on 13 Sep 09 - Cached
  • LeopoldS on 13 Sep 09
     
    how "large" could these distances be? - ready for SPS?
  • pacome delva on 14 Sep 09
     
    I don't think that the distance is the important criteria... It seems that the directivity is of the order of a laser one, so the divergence will be equivalent. Perhaps the important criteria is that the cost of these type of light sources could be cheaper...? and also perhaps what power transmission is achievable? It seems also that now that this concept could be used for to focus cheap lasers, instead of using complex optics in cd-rom players, etc... see http://news.softpedia.com/news/Highly-Directional-Semiconductor-Laser-Created-at-Harvard-90839.shtml
1More

Bat Flight Generates Complex Aerodynamic Tracks -- Hedenström et al. 316 (582... - 0 views

www.sciencemag.org/...894 BIO paper
shared by ESA ACT on 24 Apr 09 - Cached
  • ESA ACT on 24 Apr 09
     
    Non-steady state aerodynamics of flapping flight. Rather for aerospace engineers but in my eyes interesting...
1More

XI workshop on complex sytems - 0 views

science.unitn.it/...workshop.htm BIO PHY complex_systems
shared by ESA ACT on 24 Apr 09 - Cached
  • ESA ACT on 24 Apr 09
     
    could be interesting
5More

Speeding swarms of sensor robots - 2 views

web.mit.edu/...robot-algorithm-0503.html robotics swarm sensorweb AI
shared by Luís F. Simões on 04 May 11 - No Cached
LeopoldS liked it
  • the algorithm is designed for robots that will be monitoring an environment for long periods of time, tracing the same routes over and over. It assumes that the data of interest — temperature, the concentration of chemicals, the presence of organisms — fluctuate at different rates in different parts of the environment.
  • But it turns out to be a monstrously complex calculation. “It’s very hard to come up with a mathematical proof that you can really optimize the acquired knowledge,”
  • The new algorithm then determines a trajectory for the sensor that will maximize the amount of data it collects in high-priority regions, without neglecting lower-priority regions.
  • ...1 more annotation...
  • At the moment, the algorithm depends on either some antecedent estimate of rates of change for an environment or researchers’ prioritization of regions. But in principle, a robotic sensor should be able to deduce rates of change from its own measurements, and the MIT researchers are currently working to modify the algorithm so that it can revise its own computations in light of new evidence. “
  • LeopoldS on 05 May 11
     
    smart!
2More

Torsional Carbon Nanotube Artificial Muscles - 0 views

www.sciencemag.org/...science.1211220 BIO NAN carbon muscles
shared by dejanpetkow on 18 Oct 11 - No Cached
  • Actuator materials producing rotation are rare and demonstrated rotations are small, though rotary systems like electric motors, pumps, turbines and compressors are widely needed and utilized. Present motors can be rather complex and, therefore, difficult to miniaturize. We show that a short electrolyte-filled twist spun carbon nanotube yarn, which is much thinner than a human hair, functions as a torsional artificial muscle in a simple three-electrode electrochemical system, providing a reversible 15,000° rotation and 590 revolutions/minute. A hydrostatic actuation mechanism, like for nature’s muscular hydrostats, explains the simultaneous occurrence of lengthwise contraction and torsional rotation during the yarn volume increase caused by electrochemical double-layer charge injection. Use of a torsional yarn muscle as a mixer for a fluidic chip is demonstrated.
  • dejanpetkow on 18 Oct 11
     
    I have no access to the pdf, but abstract sounds interesting.
2More

A Groundbreaking Idea About Why Life Exists - 1 views

www.businessinsider.com/g-idea-of-lifes-origin-2014-12 life physics mathematics
shared by Thijs Versloot on 15 Dec 14 - No Cached
  • Thijs Versloot on 15 Dec 14
     
    Jeremy England, a 31-year-old assistant professor at the Massachusetts Institute of Technology, has derived a mathematical formula that he believes explains this capacity. The formula, based on established physics, indicates that when a group of atoms is driven by an external source of energy (like the sun or chemical fuel) and surrounded by a heat bath (like the ocean or atmosphere), it will often gradually restructure itself in order to dissipate increasingly more energy. This could mean that under certain conditions, matter inexorably acquires the key physical attribute associated with life. The simulation results made me think of Jojo's attempts to make a self-assembling space structure. Seems he may have been on the right track, just not thinking big enough
  • johannessimon81 on 15 Dec 14
     
    :-P Thanks Thijs... I do not agree with the premise of the article that a possible correlation of energy dissipation in living systems and their fitness means that one is the cause for the other - it may just be that both go hand-in-hand because of the nature of the world that we live in. Maybe there is such a drive for pre-biotic systems (like crystals and amino acids), but once life as we know it exists (i.e., heredity + mutation) it is hard to see the need for an amendment of Darwin's principles. The following just misses the essence of Darwin: "If England's approach stands up to more testing, it could further liberate biologists from seeking a Darwinian explanation for every adaptation and allow them to think more generally in terms of dissipation-driven organization. They might find, for example, that "the reason that an organism shows characteristic X rather than Y may not be because X is more fit than Y, but because physical constraints make it easier for X to evolve than for Y to evolve." Darwin's principle in its simplest expression just says that if a genome is more effective at reproducing it is more likely to dominate the next generation. The beauty of it is that there is NO need for a steering mechanism (like maximize energy dissipation) any random set of mutations will still lead to an increase of reproductive effectiveness. BTW: what does "better at dissipating energy" even mean? If I run around all the time I will have more babies? Most species that prove to be very successful end up being very good at conserving energy: trees, turtles, worms. Even complexity of an organism is not a recipe for evolutionary success: jellyfish have been successful for hundreds of millions of years while polar bears are seem to be on the way out.
2More

Test shows big data text analysis inconsistent, inaccurate - 1 views

www.computerworld.com/...s-inconsistent-inaccurate.html technology machine learning big data
shared by Thijs Versloot on 02 Feb 15 - No Cached
  • Thijs Versloot on 02 Feb 15
     
    Big data analytic systems are reputed to be capable of finding a needle in a universe of haystacks without having to know what a needle looks like. The very best ways to sort large databases of unstructured text is to use a technique called Latent Dirichlet allocation (LDA). Unfortunately, LDA is also inaccurate enough at some tasks that the results of any topic model created with it are essentially meaningless, according to Luis Amaral, a physicist whose specialty is the mathematical analysis of complex systems and networks in the real world and one of the senior researchers on the multidisciplinary team from Northwestern University that wrote the paper. Even for an easy case, big data analysis is proving to be far more complicated than many of the companies selling analysis software want people to believe.
  • Paul N on 04 Feb 15
     
    Most of those companies are using outdated algorithms like this LDA and just apply them like retards on those huge datasets. Of course they're going to come out with bad solutions. No amount of data can make up for bad algorithms.
« First ‹ Previous 61 - 80 of 87 Next ›
Showing 20▼ items per page