Papers
425.3K views | +9 today
Follow
 
Scooped by Complexity Digest
onto Papers
Scoop.it!

Positive words carry less information than negative words

We show that the frequency of word use is not only determined by the word length [1] and the average information content [2], but also by its emotional content. We have analyzed three established lexica of affective word usage in English, German, and Spanish, to verify that these lexica have a neutral, unbiased, emotional content. Taking into account the frequency of word usage, we find that words with a positive emotional content are more frequently used.

 

Positive words carry less information than negative words
Garcia D, Garas A and Schweitzer F
EPJ Data Science 2012, 1:3 (18 May 2012)

http://dx.doi.org/10.1140/epjds3

more...
No comment yet.
Papers
Recent publications related to complex systems
Your new post is loading...
Your new post is loading...
Scooped by Complexity Digest
Scoop.it!

Human Sexual Cycles are Driven by Culture and Match Collective Moods

It is a long-standing question whether human sexual and reproductive cycles are affected predominantly by biology or culture. The literature is mixed with respect to whether biological or cultural factors best explain the reproduction cycle phenomenon, with biological explanations dominating the argument. The biological hypothesis proposes that human reproductive cycles are an adaptation to the seasonal cycles caused by hemisphere positioning, while the cultural hypothesis proposes that conception dates vary mostly due to cultural factors, such as vacation schedule or religious holidays. However, for many countries, common records used to investigate these hypotheses are incomplete or unavailable, biasing existing analysis towards primarily Christian countries in the Northern Hemisphere. Here we show that interest in sex peaks sharply online during major cultural and religious celebrations, regardless of hemisphere location. This online interest, when shifted by nine months, corresponds to documented human birth cycles, even after adjusting for numerous factors such as language, season, and amount of free time due to holidays. We further show that mood, measured independently on Twitter, contains distinct collective emotions associated with those cultural celebrations, and these collective moods correlate with sex search volume outside of these holidays as well. Our results provide converging evidence that the cyclic sexual and reproductive behavior of human populations is mostly driven by culture and that this interest in sex is associated with specific emotions, characteristic of, but not limited to, major cultural and religious celebrations.

 

Human Sexual Cycles are Driven by Culture and Match Collective Moods
Ian B. Wood, Pedro Leal Varela, Johan Bollen, Luis M. Rocha, Joana Gonçalves-Sá

more...
No comment yet.
Scooped by Complexity Digest
Scoop.it!

Improving the Economic Complexity Index

How much knowledge is there in an economy? In recent years, data on the mix of products that countries export has been used to construct measures of economic complexity that estimate the knowledge available in an economy and predict future economic growth. Here we introduce a new and simpler metric of economic complexity (ECI+) that measures the total exports of an economy corrected by how difficult it is to export each product. We use data from 1973 to 2013 to compare the ability of ECI+, the Economic Complexity Index (ECI), and Fitness complexity, to predict future economic growth using 5, 10, and 20-year panels in a pooled OLS, a random effects model, and a fixed effects model. We find that ECI+ outperforms ECI and Fitness in its ability to predict economic growth and in the consistency of its estimators across most econometric specifications. On average, one standard deviation increase in ECI+ is associated with an increase in annualized growth of about 4% to 5%. We then combine ECI+ with measures of physical capital, human capital, and institutions, to find a robust model of economic growth. The ability of ECI+ to predict growth, and the value of its coefficient, is robust to these controls. Also, we find that human capital, political stability, and control of corruption; are positively associated with future economic growth, and that income is negatively associated with growth, in agreement with the traditional growth literature. Finally, we use ECI+ to generate economic growth predictions for the next 20 years and compare these predictions with the ones obtained using ECI and Fitness. These findings improve the methods available to estimate the knowledge intensity of economies and predict future economic growth.

 

Improving the Economic Complexity Index
Saleh Albeaik, Mary Kaltenberg, Mansour Alsaleh, Cesar A. Hidalgo

more...
No comment yet.
Scooped by Complexity Digest
Scoop.it!

Chinese urbanization 2050: SD modeling and process simulation

Is Chinese urbanization going to take a long time, or can its development goal be achieved by the government in a short time? What is the highest stable urbanization level that China can reach? When can China complete its urbanization? To answer these questions, this paper presents a system dynamic (SD) model of Chinese urbanization, and its validity and simulation are justified by a stock-flow test and a sensitivity analysis using real data from 1998 to 2013. Setting the initial conditions of the simulation by referring to the real data of 2013, the multi-scenario analysis from 2013 to 2050 reveals that Chinese urbanization will reach a level higher than 70% in 2035 and then proceed to a slow urbanization stage regardless of the population policy and GDP growth rate settings; in 2050, Chinese urbanization levels will reach approximately 75%, which is a stable and equilibrium level for China. Thus, it can be argued that Chinese urbanization is a long social development process that will require approximately 20 years to complete and that the ultimate urbanization level will be 75–80%, which means that in the distant future, 20–25% of China’s population will still settle in rural regions of China.

 

Chinese urbanization 2050: SD modeling and process simulation
GU Chao Lin, GUAN Wei Hua, LIU He Lin

SCIENCE CHINA Earth Sciences 60(6), 1067-1082(2017);  10.1007/s11430-016-9022-2

more...
No comment yet.
Scooped by Complexity Digest
Scoop.it!

Self-Organization and The Origins of Life: The Managed-Metabolism Hypothesis

The managed-metabolism hypothesis suggests that a cooperation barrier must be overcome if self-producing chemical organizations are to transition from non-life to life. This barrier prevents un-managed, self-organizing, autocatalytic networks of molecular species from individuating into complex, cooperative organizations. The barrier arises because molecular species that could otherwise make significant cooperative contributions to the success of an organization will often not be supported within the organization, and because side reactions and other free-riding processes will undermine cooperation. As a result, the barrier seriously limits the possibility space that can be explored by un-managed organizations, impeding individuation, complex functionality and the transition to life. The barrier can be overcome comprehensively by appropriate management which implements a system of evolvable constraints. The constraints support beneficial co-operators and suppress free riders. In this way management can manipulate the chemical processes of an autocatalytic organization, producing novel processes that serve the interests of the organization as a whole and that could not arise and persist spontaneously in an un-managed chemical organization. Management self-organizes because it is able to capture some of the benefits that are produced when its management of an autocatalytic organization promotes beneficial cooperation. Selection therefore favours the emergence of managers that take over and manage chemical organizations so as to overcome the cooperation barrier. The managed-metabolism hypothesis shows that if management is to overcome the cooperation barrier comprehensively, its interventions must be digitally coded. In this way, the hypothesis accounts for the two-tiered structure of all living cells in which a digitally-coded genetic apparatus manages an analogically-informed metabolism.

 

Self-Organization and The Origins of Life: The Managed-Metabolism Hypothesis
John E. Stewart

more...
No comment yet.
Scooped by Complexity Digest
Scoop.it!

The Fall of the Empire: The Americanization of English

As global political preeminence gradually shifted from the United Kingdom to the United States, so did the capacity to culturally influence the rest of the world. In this work, we analyze how the world-wide varieties of written English are evolving. We study both the spatial and temporal variations of vocabulary and spelling of English using a large corpus of geolocated tweets and the Google Books datasets corresponding to books published in the US and the UK. The advantage of our approach is that we can address both standard written language (Google Books) and the more colloquial forms of microblogging messages (Twitter). We find that American English is the dominant form of English outside the UK and that its influence is felt even within the UK borders. Finally, we analyze how this trend has evolved over time and the impact that some cultural events have had in shaping it.

 

The Fall of the Empire: The Americanization of English
Bruno Gonçalves, Lucía Loureiro-Porto, José J. Ramasco, David Sánchez

more...
No comment yet.
Scooped by Complexity Digest
Scoop.it!

[1707.01401] Optimal percolation on multiplex networks

Optimal percolation is the problem of finding the minimal set of nodes such that if the members of this set are removed from a network, the network is fragmented into non-extensive disconnected clusters. The solution of the optimal percolation problem has direct applicability in strategies of immunization in disease spreading processes, and influence maximization for certain classes of opinion dynamical models. In this paper, we consider the problem of optimal percolation on multiplex networks. The multiplex scenario serves to realistically model various technological, biological, and social networks. We find that the multilayer nature of these systems, and more precisely multiplex characteristics such as edge overlap and interlayer degree-degree correlation, profoundly changes the properties of the set of nodes identified as the solution of the optimal percolation problem.

 

Optimal percolation on multiplex networks
Saeed Osat, Ali Faqeeh, Filippo Radicchi

more...
No comment yet.
Scooped by Complexity Digest
Scoop.it!

Dynamics of organizational culture: Individual beliefs vs. social conformity

Dynamics of organizational culture: Individual beliefs vs. social conformity | Papers | Scoop.it

The complex nature of organizational culture challenges our ability to infer its underlying dynamics from observational studies. Recent computational studies have adopted a distinctly different view, where plausible mechanisms are proposed to describe a wide range of social phenomena, including the onset and evolution of organizational culture. In this spirit, this work introduces an empirically-grounded, agent-based model which relaxes a set of assumptions that describes past work–(a) omittance of an individual’s strive for achieving cognitive coherence; (b) limited integration of important contextual factors—by utilizing networks of beliefs and incorporating social rank into the dynamics. As a result, we illustrate that: (i) an organization may appear to be increasingly coherent in terms of its organizational culture, yet be composed of individuals with reduced levels of coherence; (ii) the components of social conformity—peer-pressure and social rank—are influential at different aggregation levels.

 

Ellinas C, Allan N, Johansson A (2017) Dynamics of organizational culture: Individual beliefs vs. social conformity. PLoS ONE 12(6): e0180193. https://doi.org/10.1371/journal.pone.0180193

more...
No comment yet.
Scooped by Complexity Digest
Scoop.it!

Scalable Co-Optimization of Morphology and Control in Embodied Machines

Evolution sculpts both the body plans and nervous systems of agents together over time. In contrast, in AI and robotics, a robot's body plan is usually designed by hand, and control policies are then optimized for that fixed design. The task of simultaneously co-optimizing the morphology and controller of an embodied robot has remained a challenge -- as evidenced by the little improvement upon early techniques over the decades since their introduction. Embodied cognition posits that behavior arises from a close coupling between body plan and sensorimotor control, which suggests why co-optimizing these two subsystems is so difficult: most evolutionary changes to morphology tend to adversely impact sensorimotor control, leading to an overall decrease in behavioral performance. Here, we further examine this hypothesis and demonstrate a technique for "morphological innovation protection", which reduces selection pressure on recently morphologically-changed individuals, thus enabling evolution some time to "readapt" to the new morphology with subsequent control policy mutations. This treatment tends to yield individuals that are significantly more fit than those that existed before the morphological change and increases evolvability. We also show the potential for this method to avoid local optima and show fitness increases further into optimization, as well as the potential for convergence to similar highly fit morphologies across widely varying initial conditions. While this technique is admittedly only the first of many steps that must be taken to achieve scalable optimization of embodied machines, we hope that theoretical insight into the cause of evolutionary stagnation in current methods will help to enable the automation of robot design and behavioral training.

 

Scalable Co-Optimization of Morphology and Control in Embodied Machines
Nick Cheney, Josh Bongard, Vytas SunSpiral, Hod Lipson

more...
No comment yet.
Scooped by Complexity Digest
Scoop.it!

Looking into Pandora's Box: The Content of Sci-Hub and its Usage

Despite the growth of Open Access, potentially illegally circumventing paywalls to access scholarly publications is becoming a more mainstream phenomenon. The web service Sci-Hub is amongst the biggest facilitators of this, offering free access to around 62 million publications. So far it is not well studied how and why its users are accessing publications through Sci-Hub. By utilizing the recently released corpus of Sci-Hub and comparing it to the data of ~28 million downloads done through the service, this study tries to address some of these questions. The comparative analysis shows that both the usage and complete corpus is largely made up of recently published articles, with users disproportionately favoring newer articles and 35% of downloaded articles being published after 2013. These results hint that embargo periods before publications become Open Access are frequently circumnavigated using Guerilla Open Access approaches like Sci-Hub. On a journal level, the downloads show a bias towards some scholarly disciplines, especially Chemistry, suggesting increased barriers to access for these. Comparing the use and corpus on a publisher level, it becomes clear that only 11% of publishers are highly requested in comparison to the baseline frequency, while 45% of all publishers are significantly less accessed than expected. Despite this, the oligopoly of publishers is even more remarkable on the level of content consumption, with 80% of all downloads being published through only 9 publishers. All of this suggests that Sci-Hub is used by different populations and for a number of different reasons, and that there is still a lack of access to the published scientific record. A further analysis of these openly available data resources will undoubtedly be valuable for the investigation of academic publishing.

 

Looking into Pandora's Box: The Content of Sci-Hub and its Usage

Bastian Greshake

F1000Research Article

more...
No comment yet.
Scooped by Complexity Digest
Scoop.it!

How an ethics-based approach works with global agendas

How an ethics-based approach works with global agendas | Papers | Scoop.it

Is “ethics” a useless word when it comes to politics, policy-making, business, international affairs, laws, governments and real-world situations? The rule of law exists and, to varying extent, it governs power systems, wills and decisions of individuals and organizations, determining the status quo we live with. Then, why have an ethics-based approach at all?

 

HOW AN ETHICS-BASED APPROACH WORKS WITH GLOBAL AGENDAS
BARIŞ BAYRAM

more...
No comment yet.
Scooped by Complexity Digest
Scoop.it!

Characterizing information importance and the effect on the spread in various graph topologies

In this paper we present a thorough analysis of the nature of news in different mediums across the ages, introducing a unique mathematical model to fit the characteristics of information spread. This model enhances the information diffusion model to account for conflicting information and the topical distribution of news in terms of popularity for a given era. We translate this information to a separate graphical node model to determine the spread of a news item given a certain category and relevance factor. The two models are used as a base for a simulation of information dissemination for varying graph topoligies. The simulation is stress-tested and compared against real-world data to prove its relevancy. We are then able to use these simulations to deduce some conclusive statements about the optimization of information spread.

 

Characterizing information importance and the effect on the spread in various graph topologies
James Flamino, Alexander Norman, Madison Wyatt

more...
No comment yet.
Suggested by Fil Menczer
Scoop.it!

Limited individual attention and online virality of low-quality information

Limited individual attention and online virality of low-quality information | Papers | Scoop.it

Social media are massive marketplaces where ideas and news compete for our attention. Previous studies have shown that quality is not a necessary condition for online virality and that knowledge about peer choices can distort the relationship between quality and popularity. However, these results do not explain the viral spread of low-quality information, such as the digital misinformation that threatens our democracy. We investigate quality discrimination in a stylized model of an online social network, where individual agents prefer quality information, but have behavioural limitations in managing a heavy flow of information. We measure the relationship between the quality of an idea and its likelihood of becoming prevalent at the system level. We find that both information overload and limited attention contribute to a degradation of the market’s discriminative power. A good tradeoff between discriminative power and diversity of information is possible according to the model. However, calibration with empirical data characterizing information load and finite attention in real social media reveals a weak correlation between quality and popularity of information. In these realistic conditions, the model predicts that low-quality information is just as likely to go viral, providing an interpretation for the high volume of misinformation we observe online.

 

Limited individual attention and online virality of low-quality information
Xiaoyan Qiu, Diego F. M. Oliveira, Alireza Sahami Shirazi, Alessandro Flammini & Filippo Menczer

Nature Human Behaviour 1, Article number: 0132 (2017)
doi:10.1038/s41562-017-0132

more...
No comment yet.
Scooped by Complexity Digest
Scoop.it!

Multiscale Information Theory and the Marginal Utility of Information

Complex systems display behavior at a range of scales. Large-scale behaviors can emerge from the correlated or dependent behavior of individual small-scale components. To capture this observation in a rigorous and general way, we introduce a formalism for multiscale information theory. Dependent behavior among system components results in overlapping or shared information. A system’s structure is revealed in the sharing of information across the system’s dependencies, each of which has an associated scale. Counting information according to its scale yields the quantity of scale-weighted information, which is conserved when a system is reorganized. In the interest of flexibility we allow information to be quantified using any function that satisfies two basic axioms. Shannon information and vector space dimension are examples. We discuss two quantitative indices that summarize system structure: an existing index, the complexity profile, and a new index, the marginal utility of information. Using simple examples, we show how these indices capture the multiscale structure of complex systems in a quantitative way.

 

Multiscale Information Theory and the Marginal Utility of Information
Benjamin Allen, Blake C. Stacey, and Yaneer Bar-Yam

Entropy 2017, 19(6), 273; doi:10.3390/e19060273

more...
No comment yet.
Scooped by Complexity Digest
Scoop.it!

The angular nature of road networks

Road networks are characterised by several structural and geometrical properties. The topological structure determines partially the hierarchical arrangement of roads, but since these are networks that are spatially constrained, geometrical properties play a fundamental role in determining the network’s behaviour, characterising the influence of each of the street segments on the system. In this work, we apply percolation theory to the UK’s road network using the relative angle between street segments as the occupation probability. The appearance of the spanning cluster is marked by a phase transition, indicating that the system behaves in a critical way. Computing Shannon’s entropy of the cluster sizes, different stages of the percolation process can be discerned, and these indicate that roads integrate to the giant cluster in a hierarchical manner. This is used to construct a hierarchical index that serves to classify roads in terms of their importance. The obtained classification is in very good correspondence with the official designations of roads. This methodology hence provides a framework to consistently extract the main skeleton of an urban system and to further classify each road in terms of its hierarchical importance within the system.

 

The angular nature of road networks
Carlos Molinero, Roberto Murcio & Elsa Arcaute
Scientific Reports 7, Article number: 4312 (2017)
doi:10.1038/s41598-017-04477-z

more...
No comment yet.
Scooped by Complexity Digest
Scoop.it!

Video Pandemics: Worldwide Viral Spreading of Psy's Gangnam Style Video

Viral videos can reach global penetration traveling through international channels of communication similarly to real diseases starting from a well-localized source. In past centuries, disease fronts propagated in a concentric spatial fashion from the the source of the outbreak via the short range human contact network. The emergence of long-distance air-travel changed these ancient patterns. However, recently, Brockmann and Helbing have shown that concentric propagation waves can be reinstated if propagation time and distance is measured in the flight-time and travel volume weighted underlying air-travel network. Here, we adopt this method for the analysis of viral meme propagation in Twitter messages, and define a similar weighted network distance in the communication network connecting countries and states of the World. We recover a wave-like behavior on average and assess the randomizing effect of non-locality of spreading. We show that similar result can be recovered from Google Trends data as well.

 

Video Pandemics: Worldwide Viral Spreading of Psy's Gangnam Style Video
Zsofia Kallus, Daniel Kondor, Jozsef Steger, Istvan Csabai, Eszter Bokanyi, Gabor Vattay

more...
No comment yet.
Suggested by Fil Menczer
Scoop.it!

The spread of fake news by social bots

The spread of fake news by social bots | Papers | Scoop.it

The massive spread of fake news has been identified as a major global risk and has been alleged to influence elections and threaten democracies. Communication, cognitive, social, and computer scientists are engaged in efforts to study the complex causes for the viral diffusion of digital misinformation and to develop solutions, while search and social media platforms are beginning to deploy countermeasures. However, to date, these efforts have been mainly informed by anecdotal evidence rather than systematic data. Here we analyze 14 million messages spreading 400 thousand claims on Twitter during and following the 2016 U.S. presidential campaign and election. We find evidence that social bots play a key role in the spread of fake news. Accounts that actively spread misinformation are significantly more likely to be bots. Automated accounts are particularly active in the early spreading phases of viral claims, and tend to target influential users. Humans are vulnerable to this manipulation, retweeting bots who post false news. Successful sources of false and biased claims are heavily supported by social bots. These results suggests that curbing social bots may be an effective strategy for mitigating the spread of online misinformation.

 

The spread of fake news by social bots

Chengcheng Shao, Giovanni Luca Ciampaglia, Onur Varol, Alessandro Flammini, Filippo Menczer

more...
No comment yet.
Scooped by Complexity Digest
Scoop.it!

Thermodynamics of Evolutionary Games

How cooperation can evolve between players is an unsolved problem of biology. Here we use Hamiltonian dynamics of models of the Ising type to describe populations of cooperating and defecting players to show that the equilibrium fraction of cooperators is given by the expectation value of a thermal observable akin to a magnetization. We apply the formalism to the Public Goods game with three players, and show that a phase transition between cooperation and defection occurs that is equivalent to a transition in one-dimensional Ising crystals with long-range interactions. We also investigate the effect of punishment on cooperation and find that punishment acts like a magnetic field that leads to an "alignment" between players, thus encouraging cooperation. We suggest that a thermal Hamiltonian picture of the evolution of cooperation can generate other insights about the dynamics of evolving groups by mining the rich literature of critical dynamics in low-dimensional spin systems.

 

Thermodynamics of Evolutionary Games
Christoph Adami, Arend Hintze

more...
No comment yet.
Scooped by Complexity Digest
Scoop.it!

To slow, or not to slow? New science in sub-second networks

What happens when you slow down part of an ultrafast network that is operating quicker than the blink of an eye, e.g. electronic exchange network, navigational systems in driverless vehicles, or even neuronal processes in the brain? This question just adopted immediate commercial, legal and political importance following U.S. financial regulators' decision to allow a new network node to intentionally introduce delays of microseconds. Though similar requests are set to follow, there is still no scientific understanding available to policymakers of the likely system-wide impact of such delays. Giving academic researchers access to (so far prohibitively expensive) microsecond exchange data would help rectify this situation. As a by-product, the lessons learned would deepen understanding of instabilities across myriad other networks, e.g. impact of millisecond delays on brain function and safety of driverless vehicle navigation systems beyond human response times.

 

To slow, or not to slow? New science in sub-second networks

Neil F. Johnson

more...
No comment yet.
Scooped by Complexity Digest
Scoop.it!

Development of structural correlations and synchronization from adaptive rewiring in networks of Kuramoto oscillators

Synchronization of non-identical oscillators coupled through complex networks is an important example of collective behavior. It is interesting to ask how the structural organization of network interactions influences this process. Several studies have uncovered optimal topologies for synchronization by making purposeful alterations to a network. Yet, the connectivity patterns of many natural systems are often not static, but are rather modulated over time according to their dynamics. This co-evolution - and the extent to which the dynamics of the individual units can shape the organization of the network itself - is not well understood. Here, we study initially randomly connected but locally adaptive networks of Kuramoto oscillators. The system employs a co-evolutionary rewiring strategy that depends only on instantaneous, pairwise phase differences of neighboring oscillators, and that conserves the total number of edges, allowing the effects of local reorganization to be isolated. We find that a simple regulatory rule - which preserves connections between more out-of-phase oscillators while rewiring connections between more in-phase oscillators - can cause initially disordered networks to organize into more structured topologies that support enhanced synchronization dynamics. We examine how this process unfolds over time, finding both a dependence on the intrinsic frequencies of the oscillators and the global coupling. For large enough coupling and after sufficient adaptation, the resulting networks exhibit degree - frequency and frequency - neighbor frequency correlations. These properties have previously been associated with optimal synchronization or explosive transitions. By considering a time-dependent interplay between structure and dynamics, this work offers a mechanism through which emergent phenomena can arise in complex systems utilizing local rules.

 

Development of structural correlations and synchronization from adaptive rewiring in networks of Kuramoto oscillators
Lia Papadopoulos, Jason Kim, Jurgen Kurths, Danielle S. Bassett

more...
No comment yet.
Scooped by Complexity Digest
Scoop.it!

[1706.05043] The thermodynamic efficiency of computations made in cells across the range of life

Biological organisms must perform computation as they grow, reproduce, and evolve. Moreover, ever since Landauer's bound was proposed it has been known that all computation has some thermodynamic cost -- and that the same computation can be achieved with greater or smaller thermodynamic cost depending on how it is implemented. Accordingly an important issue concerning the evolution of life is assessing the thermodynamic efficiency of the computations performed by organisms. This issue is interesting both from the perspective of how close life has come to maximally efficient computation (presumably under the pressure of natural selection), and from the practical perspective of what efficiencies we might hope that engineered biological computers might achieve, especially in comparison with current computational systems. Here we show that the computational efficiency of translation, defined as free energy expended per amino acid operation, outperforms the best supercomputers by several orders of magnitude, and is only about an order of magnitude worse than the Landauer bound. However this efficiency depends strongly on the size and architecture of the cell in question. In particular, we show that the {\it useful} efficiency of an amino acid operation, defined as the bulk energy per amino acid polymerization, decreases for increasing bacterial size and converges to the polymerization cost of the ribosome. This cost of the largest bacteria does not change in cells as we progress through the major evolutionary shifts to both single and multicellular eukaryotes. However, the rates of total computation per unit mass are nonmonotonic in bacteria with increasing cell size, and also change across different biological architectures including the shift from unicellular to multicellular eukaryotes.

 

The thermodynamic efficiency of computations made in cells across the range of life
Christopher P. Kempes, David Wolpert, Zachary Cohen, Juan Pérez-Mercader

more...
ComplexInsight's curator insight, July 7, 5:25 AM
The concept of computation as it occurs in biology is fascinating and this paper is likely to become a-classic - worth reading.
Scooped by Complexity Digest
Scoop.it!

Mathematicians Decode the Surprising Complexity of Cow Herds

Mathematicians Decode the Surprising Complexity of Cow Herds | Papers | Scoop.it
DO ME A favor and picture a pasture dotted with a herd of grazing cows. Some stand and stare at you with that patented cow stare, others bury their heads in the green, green grass, while still others have laid down for a rest. Tranquil, right? About as simple as life gets?
Well, I’m sorry to say that your idea of the herd life may be a lie. Because a new mathematical model posits that while they don’t look it, cow herds may be extremely dynamic, secretly contentious gatherings of warring interests. Yes, with the help of a biologist, mathematicians calculated the fascinating dynamics of cow herds, and yes, they reported it today in a journal called Chaos.
more...
No comment yet.
Scooped by Complexity Digest
Scoop.it!

Universal fractality of morphological transitions in stochastic growth processes

Universal fractality of morphological transitions in stochastic growth processes | Papers | Scoop.it

Stochastic growth processes give rise to diverse and intricate structures everywhere in nature, often referred to as fractals. In general, these complex structures reflect the non-trivial competition among the interactions that generate them. In particular, the paradigmatic Laplacian-growth model exhibits a characteristic fractal to non-fractal morphological transition as the non-linear effects of its growth dynamics increase. So far, a complete scaling theory for this type of transitions, as well as a general analytical description for their fractal dimensions have been lacking. In this work, we show that despite the enormous variety of shapes, these morphological transitions have clear universal scaling characteristics. Using a statistical approach to fundamental particle-cluster aggregation, we introduce two non-trivial fractal to non-fractal transitions that capture all the main features of fractal growth. By analyzing the respective clusters, in addition to constructing a dynamical model for their fractal dimension, we show that they are well described by a general dimensionality function regardless of their space symmetry-breaking mechanism, including the Laplacian case itself. Moreover, under the appropriate variable transformation this description is universal, i.e., independent of the transition dynamics, the initial cluster configuration, and the embedding Euclidean space.

 

Universal fractality of morphological transitions in stochastic growth processes
J. R. Nicolás-Carlock, J. L. Carrillo-Estrada & V. Dossetti
Scientific Reports 7, Article number: 3523 (2017)
doi:10.1038/s41598-017-03491-5

more...
nukem777's curator insight, June 30, 12:31 PM

Golden Apple to anyone who translates this into English.

Scooped by Complexity Digest
Scoop.it!

Empowerment As Replacement for the Three Laws of Robotics

The greater ubiquity of robots creates a need for generic guidelines for robot behavior. We focus less on how a robot can technically achieve a predefined goal and more on what a robot should do in the first place. Particularly, we are interested in the question how a heuristic should look like, which motivates the robot’s behavior in interaction with human agents. We make a concrete, operational proposal as to how the information-theoretic concept of empowerment can be used as a generic heuristic to quantify concepts, such as self-preservation, protection of the human partner, and responding to human actions. While elsewhere we studied involved single-agent scenarios in detail, here, we present proof-of-principle scenarios demonstrating how empowerment interpreted in light of these perspectives allows one to specify core concepts with a similar aim as Asimov’s Three Laws of Robotics in an operational way. Importantly, this route does not depend on having to establish an explicit verbalized understanding of human language and conventions in the robots. Also, it incorporates the ability to take into account a rich variety of different situations and types of robotic embodiment.

 

Empowerment As Replacement for the Three Laws of Robotics

Christoph Salge, Daniel Polani

Front. Robot. AI, 29 June 2017 | https://doi.org/10.3389/frobt.2017.00025

more...
No comment yet.
Scooped by Complexity Digest
Scoop.it!

1D Printing of Recyclable Robots

Recent advances in 3D printing are revolutionizing manufacturing, enabling the fabrication of structures with unprecedented complexity and functionality. Yet biological systems are able to fabricate systems with far greater complexity using a process that involves assembling and folding a linear string. Here, we demonstrate a 1D printing system that uses an approach inspired by the ribosome to fabricate a variety of specialized robotic automata from a single string of source material. This proof-of-concept system involves both a novel manufacturing platform that configures the source material using folding and a computational optimization tool that allows designs to be produced from the specification of high-level goals. We show that our 1D printing system is able to produce three distinct robots from the same source material, each of which is capable of accomplishing a specialized locomotion task. Moreover, we demonstrate the ability of the printer to use recycled material to produce new designs, enabling an autonomous manufacturing ecosystem capable of repurposing previous iterations to accomplish new tasks.

 

Title: 1D Printing of  Recyclable Robots
Authors: Daniel Cellucci, Robert MacCurdy, Hod Lipson, Sebastian Risi (2017)
In: EEE Robotics and Automation Letters (RA-L).
Link: http://ieeexplore.ieee.org/document/7950924/
PDF: http://sebastianrisi.com/wp-content/uploads/cellucci_ral17.pdf
Video: https://youtu.be/ElW0O2IiuXA

more...
No comment yet.
Suggested by mohsen mosleh
Scoop.it!

Efficient Integration in Multi-Community Networks

We study structures for efficient integration of multi-community networks where building bridges across communities incur an additional link cost compared to links within a community. Building on the connections models with direct link cost and direct and indirect benefits, we show that the efficient structure for homogeneous cost and benefit parameters, and for communities of arbitrary size, always has a diameter no greater than 3. We further show that if the internal cost is not small enough to justify a full graph for each community, integration always follows one of these two structures: Either a single star, or a new structure we introduce in this paper, called parallel-hyperstar, which is a special multi-core/periphery structure with parallel links among core nodes of different communities. We offer cost and benefit conditions where each structure is efficient and discuss the stability conditions of those structures.

more...
No comment yet.