Complexity Digest 2009.07

2009/03/27

Editor-in-Chief: Carlos Gershenson
Founding Editor: Gottfried Mayer

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Content

  1. Bringing clarity to complexity, Nature
  2. Scientist Citizens, Science
  3. Time’s Barbed Arrow: Irreversibility, Crypticity, and Stored Information, SFI Working Papers
  4. When wise words are not enough, Nature
  5. Strengths and synergies of evolved and designed controllers: A study within collective robotics, Artificial Intelligence
  6. Explosive Percolation in Random Networks, Science
  7. The Reality Game, SFI Working Papers
  8. The ubiquitin system, Nature
  9. Human Synthetic Lethal Inference as Potential Anti-cancer Target Gene Detection, SFI Working Papers
  10. The Surprising Power of Neighborly Advice, Science
  11. Epidemic thresholds for infections in uncertain networks, Complexity
  12. International Trade and the Persistence of Cultural-Institutional Diversity, SFI Working Papers
  13. Biomimetics: Steel strong, air light, Nature
  14. Electric cows, Nature
  15. Optimal Leverage from Non-ergodicity, SFI Working Papers
  16. An investigation of synchrony in transport networks, Complexity
  17. Genetic Contribution to Variation in Cognitive Function: An fMRI Study in Twins, Science
  18. Evolution and the second law of thermodynamics, arXiv
  19. Nation-State Routing: Censorship, Wiretapping, and BGP, arXiv
  20. Links & Snippets
    1. Other Publications
    2. Webcast Announcements
    3. Conference Announcements
    4. Other Announcements

  1. Bringing clarity to complexity, Nature Next Article Bookmark and Share

    Excerpts: How can something be dependent and autonomous at the same time? And why do so many systems in nature show this hierarchical organization? No one has answered these questions, but in Complexity, computer scientist Melanie Mitchell of the Santa Fe Institute, New Mexico, offers a valuable snapshot of the growing field of complex-systems science from which the answers may eventually arise. (...)
    It has become fashionable in recent years to criticize complex-systems science for generating too much hype and not offering enough practical insight. But insights into truly complex problems do not come easy. Mitchell's welcome book makes it clear that this field is making steady, if slow, progress.
    See Also: Complexity: A Guided Tour, by Melanie Mitchell. Oxford University Press, 2009.

  2. Scientist Citizens, Science Next Article Bookmark and Share

    Excerpt: Now more than ever, issues such as climate change, obesity, stem cell research, green technology, and evolution are migrating from scientific journals to the nonscience community, from school halls to the halls of Congress. It's critical that scientists venture beyond their laboratories to put these issues into the correct contexts and help the public understand what is known, unknown, and under debate.
    • Source: Scientist Citizens, Christopher Reddy, DOI: 10.1126/science.1173003, Science Vol. 323. no. 5920, p. 1405, 2009/03/13

  3. Time’s Barbed Arrow: Irreversibility, Crypticity, and Stored Information, SFI Working Papers Next Article Bookmark and Share

    Abstract: We show why the amount of information communicated between the past and future--the excess entropy--is not in general the amount of information stored in the present--the statistical complexity. This is a puzzle, and a long-standing one, since the latter is what is required for optimal prediction, but the former describes observed behavior. We layout a classification scheme for dynamical systems and stochastic processes that determines when these two quantities are the same or different. We do this by developing closed-form expressions for the excess entropy in terms of optimal causal predictors and retrodictors--the ε-machines of computational mechanics. A process's causal irreversibility and crypticity are key determining properties.

  4. When wise words are not enough, Nature Next Article Bookmark and Share

    Excerpt: In a world reeling from surprise, where once-in-a-lifetime events seem to happen every month, two things seem to be constant. The first is the inadequacy of expertise. Although the people we have anointed as experts might not admit it, they are as bewildered by the world's turbulence as the rest of us. They are also little better at predicting what is going to happen next. The second constant is a pervasive feeling of insecurity.

  5. Strengths and synergies of evolved and designed controllers: A study within collective robotics, Artificial Intelligence Next Article Bookmark and Share

    Abstract: This paper analyses the strengths and weaknesses of self-organising approaches, such as evolutionary robotics, and direct design approaches, such as behaviour-based controllers, for the production of autonomous robots' controllers, and shows how the two approaches can be usefully combined. In particular, the paper proposes a method for encoding evolved neural-network based behaviours into motor schema-based controllers and then shows how these controllers can be modified and combined to produce robots capable of solving new tasks. The method has been validated in the context of a collective robotics scenario in which a group of physically assembled simulated autonomous robots are requested to produce different forms of coordinated behaviours (e.g., coordinated motion, walled-arena exiting, and light pursuing).

  6. Explosive Percolation in Random Networks, Science Next Article Bookmark and Share

    Abstract: Networks in which the formation of connections is governed by a random process often undergo a percolation transition, wherein around a critical point, the addition of a small number of connections causes a sizable fraction of the network to suddenly become linked together. Typically such transitions are continuous, so that the percentage of the network linked together tends to zero right above the transition point. Whether percolation transitions could be discontinuous has been an open question. Here, we show that incorporating a limited amount of choice in the classic Erdös-Rényi network formation model causes its percolation transition to become discontinuous.

  7. The Reality Game, SFI Working Papers Next Article Bookmark and Share

    Excerpt: We introduce an evolutionary game with feedback between perception and reality, which we call the reality game. It is a game of chance in which the probabilities for di erent objective outcomes (e.g., heads or tails in a coin toss) depend on the amount wagered on those outcomes. By varying the `reality map', which relates the amount wagered to the probability of the outcome, it is possible to move continuously from a purely objective game in which probabilities have no dependence on wagers to a purely subjective game in which probabilities equal the amount wagered. We study self-reinforcing games, in which betting more on an outcome increases its odds, and self-defeating games, in which the opposite is true. (...)
    • Source: The Reality Game, Dmitriy Cherkashin, J. Doyne Farmer, and Seth Lloyd, DOI: SFI-WP 09-02-003, SFI Working Papers

  8. The ubiquitin system, Nature Next Article Bookmark and Share

    Excerpt: The central role of ubiquitin in cell-cycle regulation, DNA repair, cell growth, signalling and immune function is starting to become clear right down to the molecular level. Identifying irregularities in the system has opened up opportunities in drug discovery, and in diagnostics and treatment for a range of disorders, from cancer to neurodegeneration.

  9. Human Synthetic Lethal Inference as Potential Anti-cancer Target Gene Detection, SFI Working Papers Next Article Bookmark and Share

    Excerpt: Two genes are called synthetic lethal (SL) if mutation of either alone is not lethal, but mutation of both leads to death or a significant decrease in the organism’s fitness. The detection of SL gene pairs constitutes a promising alternative for anti-cancer therapy. As cancer cells exhibit a large number of mutations, the determination of these mutated genes’ SL partners may provide specific anti-cancer drug candidates, with minor perturbations to the healthy cells. (...)

  10. The Surprising Power of Neighborly Advice, Science Next Article Bookmark and Share

    Abstract: Two experiments revealed that (i) people can more accurately predict their affective reactions to a future event when they know how a neighbor in their social network reacted to the event than when they know about the event itself and (ii) people do not believe this. Undergraduates made more accurate predictions about their affective reactions to a 5-minute speed date (n = 25) and to a peer evaluation (n = 88) when they knew only how another undergraduate had reacted to these events than when they had information about the events themselves. Both participants and independent judges mistakenly believed that predictions based on information about the event would be more accurate than predictions based on information about how another person had reacted to it.
    • Source: The Surprising Power of Neighborly Advice, Daniel T. Gilbert, Matthew A. Killingsworth, Rebecca N. Eyre, Timothy D. Wilson, DOI: 10.1126/science.1166632, Science Vol. 323. no. 5921, pp. 1617 - 1619, 2009/03/20

  11. Epidemic thresholds for infections in uncertain networks, Complexity Next Article Bookmark and Share

    Abstract: Over the last 10 years, the field of mathematical epidemiology has piqued the interest of complex-systems researchers, resulting in a tremendous volume of work exploring the effects of population structure on disease propagation. Much of this research focuses on computing epidemic threshold tests, and in practice several different tests are often used interchangeably. We summarize recent literature that attempts to clarify the relationships among different threshold criteria, systematize the incorporation of population structure into a general infection framework, and discuss conditions under which interaction topology and infection characteristics can be decoupled in the computation of the basic reproductive ratio, R0. We then present methods for making predictions about disease spread when only partial information about the routes of transmission is available. These methods include approximation techniques and bounds obtained via spectral graph theory, and are applied to several data sets.

  12. International Trade and the Persistence of Cultural-Institutional Diversity, SFI Working Papers Next Article Bookmark and Share

    Excerpt: Cultural and institutional differences among nations may affect the ratios of marginal costs of goods in autarchy and thus be the basis of specialization and comparative advantage as long as these differences are not eliminated by trade. We provide experimental and historical evidence motivating a model of the joint dynamics of preferences and institutions under autarchy and trade. (...)

  13. Biomimetics: Steel strong, air light, Nature Next Article Bookmark and Share

    Excerpt: Applying a voltage across the width of the ribbon electrically charges the nanotubes; their mutual repulsion can increase the material's width by a factor of three in an instant. A voltage along the length of the ribbon triggers contraction, making the material dense and stiff. The muscles can be turned on and off 1,000 times a second. They can also be 'frozen' at any desired density, which might open up a range of applications depending on the optical and electronic properties of a specific arrangement of nanotubes.
    See Also: Science 323, 1575â€"1578 (2009)>

  14. Electric cows, Nature Next Article Bookmark and Share

    Excerpt: Having previously shown statistically that cows and deer preferentially align their bodies northâ€"south, Hynek Burda of the University of Duisburg-Essen in Germany and his colleagues now provide more evidence for these animals' magnetic sensing. (...)
    Using satellite and aerial photographs, the researchers show that 1,699 cows grazing within 50 metres of overhead power lines at various European locations were randomly oriented. Field observations of 653 deer within 50 metres of power lines in the Czech Republic also revealed random orientation.
    See Also: Proc. Natl Acad. Sci. USA doi: 10.1073/pnas.0811194106 (2009)>
    • Source: Electric cows, DOI: 10.1038/458389a, Nature 458, 389, 2009/03/26

  15. Optimal Leverage from Non-ergodicity, SFI Working Papers Next Article Bookmark and Share

    Excerpt: In modern portfolio theory, the balancing of expected returns on investments against uncertainties in those returns is aided by the use of utility functions. The Kelly criterion offers another approach, rooted in information theory, that always implies logarithmic utility. The two approaches seem incompatible, too loosely or too tightly constraining investors’ risk preferences, from their respective perspectives. This incompatibility goes away by noticing that the model used in both approaches, geometric Brownian motion, is a non-ergodic process, in the sense that ensemble-average returns differ from time-average returns in a single realization. (...)

  16. An investigation of synchrony in transport networks, Complexity Next Article Bookmark and Share

    Excerpt: The cumulative degree distributions of transport networks, such as air transportation networks and respiratory neuronal networks, follow power laws. The significance of power laws with respect to other network performance measures, such as throughput and synchronization, remains an open question. Evolving methods for the analysis and design of air transportation networks must be able to address network performance in the face of increasing demands and the need to contain and control local network disturbances, such as congestion. Toward this end, we investigate functional relationships that govern the performance of transport networks (...)

  17. Genetic Contribution to Variation in Cognitive Function: An fMRI Study in Twins, Science Next Article Bookmark and Share

    Abstract: Little is known about the genetic contribution to individual differences in neural networks subserving cognition function. In this functional magnetic resonance imaging (fMRI) twin study, we found a significant genetic influence on brain activation in neural networks supporting digit working memory tasks. Participants activating frontal-parietal networks responded faster than individuals relying more on language-related brain networks. There were genetic influences on brain activation in language-relevant brain circuits that were atypical for numerical working memory tasks as such. This suggests that differences in cognition might be related to brain activation patterns that differ qualitatively among individuals.

  18. Evolution and the second law of thermodynamics, arXiv Next Article Bookmark and Share

    Abstract: Skeptics of biological evolution often claim that evolution requires a decrease in entropy, giving rise to a conflict with the second law of thermodynamics. This argument is fallacious because it neglects the large increase in entropy provided by sunlight striking the Earth. A recent article provided a quantitative assessment of the entropies involved and showed explicitly that there is no conflict. That article rests on an unjustified assumption about the amount of entropy reduction involved in evolution. I present a refinement of the argument that does not rely on this assumption.

  19. Nation-State Routing: Censorship, Wiretapping, and BGP, arXiv Next Article Bookmark and Share

    Excerpt: If an entire nation's worth of ISPs apply common policies to Internet traffic, the global implications could be significant. For instance, how many countries rely on China or Great Britain (known traffic censors) to transit their traffic? (...) Our results show that some countries known for their national policies, such as Iran and China, have relatively little effect on interdomain routing, while three countries (the United States, Great Britain, and Germany) are central to international reachability, and their policies thus have huge potential impact.

  20. Links & Snippets Next Article Bookmark and Share

    1. Other Publications Next Article Bookmark and Share

      1. Hierarchical Models, Marginal Polytopes, and Linear Codes, Thomas Kahle, Walter Wenzel, and Nihat Ay, SFI Working Papers, DOI: SFI-WP 09-01-001
      2. An exactly solvable model of theoretical ecosystem assembly, J.A. Capitan, J.A. Cuesta and J. Bascompte, 2009/03/16, arXiv:0903.2691
      3. Switcher-random-walks: a cognitive-inspired mechanism for network exploration, Joaqu\'in Go\~ni, I\~nigo Martincorena, Bernat Corominas-Murtra, Gonzalo Arrondo, Sergio Ardanza-Trevijano, Pablo Villoslada, 2009/03/24, arXiv 0903.4132
      4. On the Robustness of NK-Kauffman Networks Against Changes in their Connections and Boolean Functions, Federico Zertuche, 2009/03/24, arXiv:0903.4161

    2. Webcast Announcements Next Article Bookmark and Share

      1. Memorial Service for Dr Gottfried Mayer, Founding Editor Complexity Digest, Taipei, Taiwan (1954-2009). Video [RM], 09/02/13

      2. Making Connections: In Memory and Celebration of the Life of Dr. Gottfried Mayer (1954-2009). Video [RM] [MPG], 09/02/13

      3. Eulogy for Gottfried Mayer by Dean LeBaron [WMV, 25 Mb], [RM, 10 Mb], 09/02/10

      4. Can Ants Solve Traffic Jams?, Danielle Parsons, Slatev.com, 08/07/22

      5. Reseau Nationale des Systemes Complexes , (in French), 2007
      6. World Economic Forum , Davos, Switzerland, 08/01/22-27
      7. TED Talks, TED Conferences LLC , since 2006
      8. Talking Robots: The PodCast on Robotics and AI, Ecole Polytechnique Federale de Lausanne, Switzerland, 06/11/03
      9. Potentials of Complexity Science for Business, Governments, and the Media 2006, Budapest, Hungary, 06/08/03-05
      10. 6th Intl Conf on Complex Systems (ICCS), Boston, MA, 06/06/25-30
      11. Artificial Life X, 10th Intl Conf on the Simulation and Synthesis of Living Systems, Bloomington, IN, USA. 2006/06/03-07
      12. 6th Understanding Complex Systems Symposium, Urbana-Champaign, Il, 06/05/15-18
      13. Ralph Abraham on Complexity Digest, , Calcutta, India, 05/12/27
      14. An Afternoon with Michael Crichton, Washington, 05/11/06
      15. Illuminating the Shadow of the Future, Ann Arbor, Mi 05/09/23-25
      16. Open Network of Centres of Excellence in Complex Systems - Brainstorming Meeting, Paris, France 05/09/19-23
      17. Complexity, Science & Society Conference 2005, U. Liverpool, UK 2005/09/11-14
      18. ECAL 2005 - VIIIth European Conference on Artificial Life, Canterbury, Kent, UK 2005/09/5-9
      19. T. Irene Sanders, Executive Director and Founder, The Washington Center for Complexity & Public Policy, 05/08/27, QuickTime video (10:38 min), Podcast
      20. North American Society for the Psychology of Sport and Physical Activity 2005 Conference, Virtual Conference Network, St. Pete's Beach, Florida, 05/06/09-11
      21. Understanding Complex Systems - Computational Complexity and Bioinformatics, Virtual Conference Network, Urbana-Champaign, Il, UIUC, 05/05/16-19
      22. Nonlinearity, Fluctuations, and Complexity, with a celebration of the 65th birthday of Gregoire Nicolis. , Complexity Session, Universite' Libre de Bruxelles, Brussels, Belgium, 05/03/16
      23. 1st European Conference on Complex Systems, Torino, Italy, 04/12/5-7
      24. From Autopoiesis to Neurophenomenology: A Tribute to Francisco Varela (1946-2001), Paris, France, 2004/06/18-20
      25. Evolutionary Epistemology, Language, and Culture, Brussels, Belgium, 04/05/26-28
      26. International Conference on Complex Systems 2004, Boston, 04/05/16-21
      27. Nonlinear Dynamics And Chaos: Lab Demonstrations, Strogatz, Steven H., Internet-First University Press, 1994
      28. CERN Webcast Service, Streamed videos of Archived Lectures and Live Events
      29. Dean LeBaron's Archive of Daily Video Commentary, Ongoing Since February 1998
      30. Edge Videos

    3. Conference Announcements Next Article Bookmark and Share

      1. 2009 IEEE Symposium Series on Computational Intelligence, Nashville, Tennessee, USA,09/03/30-04/02
      2. Inaugural Meeting of the Nonlinear and Complex Physics Group, University of Manchester, UK, 09/04/01-02
      3. INFORMATION PROCESSING IN CELLS AND TISSUES (IPCAT 2009) "From Small Scale Dynamics To Understanding Systems Behavior", Ascona, Switzerland, 09/04/05-09
      4. 7th Annual Bio-IT World Conference & Expo, 09/04/27-29, Boston, MA
      5. 2nd Chaotic Modeling and Simulation International Conference (CHAOS2009), Chania, Crete, Greece, 09/06/01-05
      6. International Workshop on Coping with Crises in Complex Socio-Economic Systems, Zurich, Switzerland, 09/06/8-13
      7. NECSI Summer School, Cambridge, MA, USA, 09/06/08-26
      8. 20th Intl Conf on Noise and Fluctuations, Pisa, Italy, 09/06/14-19
      9. First International Workshop on Morphogenetic Engineering, Paris, France, 09/06/19
      10. 17th Intl Workshop on Nonlinear Dynamics of Electronic Systems (NDES 2009), Rapperswil, Switzerland, 09/06/21-24
      11. First Latin American Conference on Computing and Philosophy, Mexico City, Mexico, June 22-23, 2009
      12. Emergence in Chemical Systems, , Anchorage, Alaska, 09/06/22-26
      13. From Systemic Thinking to Systems Design and Systems Practice, Xanthi, Greece, 09/06/24-27
      14. International Conference on Computational Aspects of Social Networks - CASoN 2009, Fontainebleau, France, 09/06/24-27
      15. CCSA 2009 The 3rd International Conference on Complex Systems and Applications, University of Le Havre, France. 09/06/29-07/02
      16. 7th Intl Conf on Computing, Communications and Control Technologies: CCCT 2009, Orlando, Florida, USA. 09/07/10-13
      17. Complex Systems and Social Simulations, Budapest, Hungary, 09/07/13-24
      18. Second International Workshop on Nonlinear Dynamics and Synchronization (INDS'09), Klagenfurt, Austria, 09/07/20-21
      19. The 19th Annual Intl Conf Society for Chaos Theory in Psychology & Life Sciences , Milwaukee, WI USA, 09/07/23-25
      20. 2009 Intl Conf of the System Dynamics Society, Albuquerque, New Mexico, 09/07/26-30
      21. 5th Intl Conf on Fractals and Dynamic Systems in Geoscience, Townsville, Australia, 09/08/13-14
      22. Darwin Meets von Neumann: European Conference on Artificial Life 2009, Budapest, Hungary, 09/09/13-16
      23. IEEE International Conference on Self-Adaptive and Self-Organizing Systems , San Francisco, California, 09/09/14-18
      24. 6th Conference of the European Social Simulation Association, Guilford, UK, 09/09/14-18
      25. European Conference on Complex Systems 2009 (ECCS'09), University of Warwick, UK, 09/09/21-25
      26. International Workshop on Natural Computing, Himeji, Japan, 09/09/23-25
      27. The 2009 International Conference on Adaptive & Intelligent Systems (ICAIS'09), Klagenfurt, Austria, 09/09/24-26
      28. Complexity Theories of Cities have come of Age, Delft Netherlands, 09/09/24-27
      29. Natural and Biomimetic Mechanosensing, Dresden, Germany, 09/10/26-28
      30. 9th International Conference on Intelligent Systems Design and Applications, Pisa, Italy, 09/11/30-12/02
      31. 5th Biennial Convention about the philosophical, epistemological, and methodological implications of the Theory of Complexity, Havana, Cuba, 10/01/6-8

    4. Other Announcements Bookmark and Share

      • Postdoc positions: The C3 - Centro de Ciencias de la Complejidad, a new interdisciplinary, inter-institutional research center based at the Universidad Nacional Autonoma de Mexico (UNAM) plans to have several openings for postdoctoral candidates in the coming months. The center currently has affiliated to it more than 50 researchers and 40 students from all the major scientific disciplines. The main research topics at the moment are: Genetic networks and Systems Biology, Ecological Complexity, Social Complexity and Computational Intelligence. Salary will be in the region of 20-25,000 pesos per month.
        Interested candidates are asked to send a CV, a statement of research interests and the names of at least three potential referees to:
        Dr. Chris Stephens (Ecological Complexity and Computational Intelligence) stephens@nucleares.unam.mx
        Dra. Elena Alvarez-Buylla (Systems Biology) eabuylla@gmail.com
        Dr. Gustavo Martinez-Mekler (Social Complexity and other areas) mekler@ce.fis.unam.mx

      • New Book: Complexity: A Guided Tour, by Melanie Mitchell. Oxford University Press, 2009.
        What enables individually simple insects like ants to act with such precision and purpose as a group? How do trillions of individual neurons produce something as extraordinarily complex as consciousness? What is it that guides self-organizing structures like the immune system, the World Wide Web, the global economy, and the human genome? These are just a few of the fascinating and elusive questions that the science of complexity seeks to answer.
        In this remarkably accessible and companionable book, leading complex systems scientist Melanie Mitchell provides an intimate, detailed tour of the sciences of complexity, a broad set of efforts that seek to explain how large-scale complex, organized, and adaptive behavior can emerge from simple interactions among myriad individuals. Comprehending such systems requires a wholly new approach, one that goes beyond traditional scientific reductionism and that re-maps long-standing disciplinary boundaries. Based on her work at the Santa Fe Institute and drawing on its interdisciplinary strategies, Mitchell brings clarity to the workings of complexity across a broad range of biological, technological, and social phenomena, seeking out the general principles or laws that apply to all of them. She explores as well the relationship between complexity and evolution, artificial intelligence, computation, genetics, information processing, and many other fields.
        Richly illustrated and vividly written, Complexity: A Guided Tour offers a comprehensive and eminently comprehensible overview of the ideas underlying complex systems science, the current research at the forefront of this field, and the prospects for the field's contribution to solving some of the most important scientific questions of our time.


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