dunnettreader + agent-based_models   8

M Starnini, M Frasca & A Baronchelli - Emergence of metapopulations and echo chambers in mobile agent - Scientific Reports (2016) - nature.com
Michele Starnini, Mattia Frasca & Andrea Baronchelli -- Scientific Reports 6, Article number: 31834 (2016), doi:10.1038/srep31834
Multi-agent models often describe populations segregated either in the physical space, i.e. subdivided in metapopulations, or in the ecology of opinions, i.e. partitioned in echo chambers. Here we show how both kinds of segregation can emerge from the interplay between homophily and social influence in a simple model of mobile agents endowed with a continuous opinion variable. In the model, physical proximity determines a progressive convergence of opinions but differing opinions result in agents moving away from each others. This feedback between mobility and social dynamics determines the onset of a stable dynamical metapopulation scenario where physically separated groups of like-minded individuals interact with each other through the exchange of agents. The further introduction of confirmation bias in social interactions, defined as the tendency of an individual to favor opinions that match his own, leads to the emergence of echo chambers where different opinions coexist also within the same group. We believe that the model may be of interest to researchers investigating the origin of segregation in the offline and online world. -- Downloaded to Tab S2
article  downloaded  systems-complex_adaptive  social_process  dynamic_attractors  segregation  epistemic_closure  public_opinion  social_media  multi-agent_models  agent-based_models  agency-structure  emergence 
august 2016 by dunnettreader
Krasnow et al - Group Cooperation without Group Selection: Modest Punishment Can Recruit Much Cooperation, PLoS ONE (April 2015) | via Researchgate
Max M Krasnow, Andrew W Delton, Leda Cosmides, John Tooby -- PLoS ONE 04/2015; 10(4):e0124561. DOI: 10.1371/journal.pone.0124561 (Impact Factor: 3.23). -- ABSTRACT -- Humans everywhere cooperate in groups to achieve benefits not attainable by individuals. Individual effort is often not automatically tied to a proportionate share of group benefits. This decoupling allows for free-riding, a strategy that (absent countermeasures) outcompetes cooperation. Empirically and formally, punishment potentially solves the evolutionary puzzle of group cooperation. Nevertheless, standard analyses appear to show that punishment alone is insufficient, because second-order free riders (those who cooperate but do not punish) can be shown to outcompete punishers. Consequently, many have concluded that other processes, such as cultural or genetic group selection, are required. Here, we present a series of agent-based simulations that show that group cooperation sustained by punishment easily evolves by individual selection when you introduce into standard models more biologically plausible assumptions about the social ecology and psychology of ancestral humans. -- downloaded pdf to Note
article  biocultural_evolution  evolutionary_biology  evolution-social  evo_psych  natural_selection  cooperation  free-riding  evolution-group_selection  game_theory  punishment-altruistic  norms  agent-based_models  downloaded 
january 2016 by dunnettreader
Egmont Kakarot-Handtke - Economics for Economists :: SSRN - update April 2015
University of Stuttgart - Institute of Economics and Law -- The characteristic capability of science – to turn whatever it might touch into knowledge – seems to have eluded economics. Currently, economists do not understand how the economy works. To get out of the cul-de-sac requires a paradigm shift. It consists in replacing behavioral axioms by structural axioms. The subject matter of theoretical economics is not human behavior but systemic behavior. From the structural analysis follows a new Law of Supply and Demand and a new Profit Law for the economy as a whole. The conventional supply-demand-equilibrium approach is refuted. This implies that the reliance on the spontaneous order metaphor is unfounded. -' Number of Pages in PDF File: 29 -- downloaded pdf to Note
paper  economic_theory  macroeconomics  profit  equilibrium  behavioralism  agency-structure  agent-based_models  downloaded 
september 2015 by dunnettreader
Giovanni Dosi, et al -Fiscal and Monetary Policies in Complex Evolving Economies -- 2013 :: SSRN
Giovanni Dosi, Giorgio Fagiolo, Mauro Napoletano, Andrea Roventini, Tania Treibich -- In this paper we explore the effects of alternative combinations of fiscal and monetary policies under different income distribution regimes. In particular, we aim at evaluating fiscal rules in economies subject to banking crises and deep recessions. We do so using an agent-based model populated by heterogeneous capital- and consumption-good firms, heterogeneous banks, workers/consumers, a Central Bank and a Government. We show that the model is able to reproduce a wide array of macro and micro empirical regularities, including stylised facts concerning financial dynamics and banking crises. Simulation results suggest that the most appropriate policy mix to stabilize the economy requires unconstrained counter-cyclical fiscal policies, where automatic stabilizers are free to dampen business cycles fluctuations, and a monetary policy targeting also employment. Instead, "discipline-guided" fiscal rules such as the Stability and Growth Pact or the Fiscal Compact in the Eurozone always depress the economy, without improving public finances, even when escape clauses in case of recessions are considered. Consequently, austerity policies appear to be in general self-defeating. Furthermore, we show that the negative effects of austere fiscal rules are magnified by conservative monetary policies focused on inflation stabilization only. Finally, the effects of monetary and fiscal policies become sharper as the level of income inequality increases. -- Pages in PDF File: 38 -- Keywords: agent-based model, fiscal policy, monetary policy, banking crises, income inequality, austerity policies, disequilibrium dynamics -- downloaded pdf to Note
paper  SSRN  macroeconomics  fiscal_policy  fiscal_drag  austerity  Eurozone  EU_governance  EU  equilibrium  financial_crisis  bank_runs  inequality  countercyclical_policy  agent-based_models  complexity  recessions  dynamic_attractors  complex_adaptive_systems  downloaded 
april 2015 by dunnettreader
Rajiv Sethi: The Agent-Based Method - August 2014
It's nice to see some attention being paid to agent-based computational models on economics blogs, but Chris House has managed to misrepresent the methodology so completely that his post is likely to do more harm than good. -- Useful discussion of both DSGE and agent-based modeling approaches plus links. Chris House, for a highly touted "expert", keeps exposing his combination of ignorance and bias ("facts have a conservative bias"!!) Apparently since he already knows what the facts are going to tell him, he doesn't actually have to learn something about which he is ignorant but feels free to spout what "must" be the case. Extraordinary indictment of the upper levels of the economics professoriate. Seth's post is a fine description of what agent-based models are about, and the dilemmas of coming up with criteria for evaluating robustness of research results -- a problem which DSGE papers don't seem to have, apparently because of the agreed upon math and that most of the variables are exogenous chosen by the modeler, and theoretical papers which can be judged on the coherence of their mathematical logic. Links to some agent-based work - Seth himself working on market structure and trading practices (e.g. GFT) within a "market ecology" framework
economic_theory  macroeconomics  economic_models  rationality-economics  markets  markets-structure  ecology  ecology-economic  agent-based_models  evolution-as-model  evolution-social  links 
february 2015 by dunnettreader
Daniel Little - Emergentism and generationism | Understanding Society 3014
So Epstein and Page both make use of the methods of agent based modeling, but they disagree about the idea of emergence. Page believes that complex adaptive systems give rise to properties that are emergent and irreducible; whereas Epstein doesn't think the idea makes a lot of sense. Rather, Epstein's view depends on the idea that we can reproduce (generate) the macro phenomena based on a model involving the agents and their interactions. Macro phenomena are generated by the interactions of the units; whereas for Page and Miller, macro phenomena in some systems have properties that cannot be easily derived from the activities of the units. At the moment, anyway, I find myself attracted to Herbert Simon's effort to split the difference by referring to "weak emergence" (link to amazon kindle): - Epstein paper dowmloaded to iPhone
social_theory  emergence  complex_adaptive_systems  complexity  agent-based_models  methodology  methodological_individualism  causation-social  anthropology  historical_sociology  fownloaded  kindle-available 
january 2015 by dunnettreader
Pei Wang - A General Theory of Intelligence [an e-book under development] | Home
This eBook is an attempt to establish a theory that identifies the commonality within various forms intelligence, including human intelligence, computer intelligence, animal intelligence, alien intelligence, group intelligence, etc. -- NARS (Non-Axiomatic Reasoning System) - Most of the existing AI inference works with semi-axiomatic systems, which attempt to make partial extension or revision of mathematical logic, while keeping the other parts. What AI really needs are non-axiomatic systems, which do not assume the sufficiency of knowledge and resources in any aspect of the system. NARS is a concrete example of non-axiomatic system which uses a formal language "Narsese" to represent goals, actions, and beliefs.The basic unit of the language is term, which can be thought of as the name or label of a concept in the system. (..) The meaning of a term is determined by its extension and intension, which are the collection of the inheritance relations between this term and other terms, obtained from the experience of the system. NARS includes three variants of the inheritance relation: similarity (symmetric inheritance), implication (derivability), and equivalence (symmetric implication). (..)The meaning of a compound term is partially determined by its logical relations with its components, and partially by the system's experience on the compound term as a whole. Event is a special type of statement that have a time-dependent truth-value. Operation is a special type of event that can occur by the system's decision. Goal is a special type of event, that the system is attempting to realize, by carrying out certain operations. Beside goals to be achieved, NARS can accept tasks that are knowledge to be absorbed and questions to be answered. (..)If a event is judged to imply the achieving of a goal, then the desirability of the event is increased, and the system will also evaluate its plausibility(..). When an event is both desirable and plausible, the system will make the decision to turn the event into a goal to be actually pursued. The basic function of inference rules in NARS is to derive new beliefs from current beliefs.
etexts  books  intelligence  artificial_intelligence  mind  systems-complex_adaptive  systems-reflexive  systems_theory  epistemology-social  cognition  cognition-social  agent-based_models  logic  inference  decision_theory  rationality  rationality-bounded  learning  website  EF-add 
november 2014 by dunnettreader
UMA RAMAMURTHY, STAN FRANKLIN, and PULIN AGRAWAL - SELF-SYSTEM IN A MODEL OF COGNITION | International Journal of Machine Consciousness: Vol. 04, No. 02 December 2012 (World Scientific)
Philosophers, psychologists and neuroscientists have proposed various forms of a "self" in humans and animals. All of these selves seem to have a basis in some form of consciousness. The Global Workspace Theory (GWT) [Baars, 1988, 2003] suggests a mostly unconscious, many-layered self-system. In this paper, we consider several issues that arise from attempts to include a self-system in a software agent/cognitive robot. We explore these issues in the context of the LIDA model [Baars and Franklin, 2009; Ramamurthy et al., 2006] which implements the Global Workspace Theory.
Keywords: Consciousness; self-system; Global Workspace Theory; LIDA model
article  consciousness  self  mind  unconscious  neuroscience  artificial_intelligence  agent-based_models  downloaded  EF-add 
november 2014 by dunnettreader

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