5,610 research outputs found
Largenet2: an object-oriented programming library for simulating large adaptive networks
The largenet2 C++ library provides an infrastructure for the simulation of
large dynamic and adaptive networks with discrete node and link states. The
library is released as free software. It is available at
http://rincedd.github.com/largenet2. Largenet2 is licensed under the Creative
Commons Attribution-NonCommercial 3.0 Unported License.Comment: 2 pages, 1 figur
Adaptive cyclically dominating game on co-evolving networks: Numerical and analytic results
A co-evolving and adaptive Rock (R)-Paper (P)-Scissors (S) game (ARPS) in
which an agent uses one of three cyclically dominating strategies is proposed
and studied numerically and analytically. An agent takes adaptive actions to
achieve a neighborhood to his advantage by rewiring a dissatisfying link with a
probability or switching strategy with a probability . Numerical
results revealed two phases in the steady state. An active phase for
has one connected network of agents using different
strategies who are continually interacting and taking adaptive actions. A
frozen phase for has three separate clusters of agents using
only R, P, and S, respectively with terminated adaptive actions. A mean-field
theory of link densities in co-evolving network is formulated in a general way
that can be readily modified to other co-evolving network problems of multiple
strategies. The analytic results agree with simulation results on ARPS well. We
point out the different probabilities of winning, losing, and drawing a game
among the agents as the origin of the small discrepancy between analytic and
simulation results. As a result of the adaptive actions, agents of higher
degrees are often those being taken advantage of. Agents with a smaller
(larger) degree than the mean degree have a higher (smaller) probability of
winning than losing. The results are useful in future attempts on formulating
more accurate theories.Comment: 17 pages, 4 figure
Clustered marginalization of minorities during social transitions induced by co-evolution of behaviour and network structure
Large-scale transitions in societies are associated with both individual
behavioural change and restructuring of the social network. These two factors
have often been considered independently, yet recent advances in social network
research challenge this view. Here we show that common features of societal
marginalization and clustering emerge naturally during transitions in a
co-evolutionary adaptive network model. This is achieved by explicitly
considering the interplay between individual interaction and a dynamic network
structure in behavioural selection. We exemplify this mechanism by simulating
how smoking behaviour and the network structure get reconfigured by changing
social norms. Our results are consistent with empirical findings: The
prevalence of smoking was reduced, remaining smokers were preferentially
connected among each other and formed increasingly marginalised clusters. We
propose that self-amplifying feedbacks between individual behaviour and dynamic
restructuring of the network are main drivers of the transition. This
generative mechanism for co-evolution of individual behaviour and social
network structure may apply to a wide range of examples beyond smoking.Comment: 16 pages, 5 figure
Correlation of Positive and Negative Reciprocity Fails to Confer an Evolutionary Advantage: Phase Transitions to Elementary Strategies
Economic experiments reveal that humans value cooperation and fairness. Punishing unfair behavior is therefore common, and according to the theory of strong reciprocity, it is also directly related to rewarding cooperative behavior. However, empirical data fail to confirm that positive and negative reciprocity are correlated. Inspired by this disagreement, we determine whether the combined application of reward and punishment is evolutionarily advantageous. We study a spatial public goods game, where in addition to the three elementary strategies of defection, rewarding, and punishment, a fourth strategy that combines the latter two competes for space. We find rich dynamical behavior that gives rise to intricate phase diagrams where continuous and discontinuous phase transitions occur in succession. Indirect territorial competition, spontaneous emergence of cyclic dominance, as well as divergent fluctuations of oscillations that terminate in an absorbing phase are observed. Yet, despite the high complexity of solutions, the combined strategy can survive only in very narrow and unrealistic parameter regions. Elementary strategies, either in pure or mixed phases, are much more common and likely to prevail. Our results highlight the importance of patterns and structure in human cooperation, which should be considered in future experiments
Moment Closure - A Brief Review
Moment closure methods appear in myriad scientific disciplines in the
modelling of complex systems. The goal is to achieve a closed form of a large,
usually even infinite, set of coupled differential (or difference) equations.
Each equation describes the evolution of one "moment", a suitable
coarse-grained quantity computable from the full state space. If the system is
too large for analytical and/or numerical methods, then one aims to reduce it
by finding a moment closure relation expressing "higher-order moments" in terms
of "lower-order moments". In this brief review, we focus on highlighting how
moment closure methods occur in different contexts. We also conjecture via a
geometric explanation why it has been difficult to rigorously justify many
moment closure approximations although they work very well in practice.Comment: short survey paper (max 20 pages) for a broad audience in
mathematics, physics, chemistry and quantitative biolog
Bio-communication of Plants
Plants communicate with a great variety of symbiotic partners, above and below ground. Constant monitoring of signals of biotic origin as well as abiotic environmental influences allows plants to generate appropriate response behavior. These communication processes are primarily sign-mediated interactions and not simply an exchange of information. They involve active coordination and active organization of a great variety of different behavioural patterns – mediated by signs
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