26,557 research outputs found
Evolution of Cooperation among Mobile Agents
We study the effects of mobility on the evolution of cooperation among mobile
players, which imitate collective motion of biological flocks and interact with
neighbors within a prescribed radius . Adopting the prisoner's dilemma game
and the snowdrift game as metaphors, we find that cooperation can be maintained
and even enhanced for low velocities and small payoff parameters, when compared
with the case that all agents do not move. But such enhancement of cooperation
is largely determined by the value of , and for modest values of , there
is an optimal value of velocity to induce the maximum cooperation level.
Besides, we find that intermediate values of or initial population
densities are most favorable for cooperation, when the velocity is fixed.
Depending on the payoff parameters, the system can reach an absorbing state of
cooperation when the snowdrift game is played. Our findings may help
understanding the relations between individual mobility and cooperative
behavior in social systems.Comment: 15 pages, 5 figure
Embodied Evolution in Collective Robotics: A Review
This paper provides an overview of evolutionary robotics techniques applied
to on-line distributed evolution for robot collectives -- namely, embodied
evolution. It provides a definition of embodied evolution as well as a thorough
description of the underlying concepts and mechanisms. The paper also presents
a comprehensive summary of research published in the field since its inception
(1999-2017), providing various perspectives to identify the major trends. In
particular, we identify a shift from considering embodied evolution as a
parallel search method within small robot collectives (fewer than 10 robots) to
embodied evolution as an on-line distributed learning method for designing
collective behaviours in swarm-like collectives. The paper concludes with a
discussion of applications and open questions, providing a milestone for past
and an inspiration for future research.Comment: 23 pages, 1 figure, 1 tabl
Dynamics of organizational culture: Individual beliefs vs. social conformity
The complex nature of organizational culture challenges our ability to infers
its underlying dynamics from observational studies. Recent computational
studies have adopted a distinct 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 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.Comment: 20 pages, 8 figure
How groups can foster consensus: The case of local cultures
A local culture denotes a commonly shared behaviour within a cluster of
firms. Similar to social norms or conventions, it is an emergent feature
resulting from the firms' interaction in an economic network. To model these
dynamics, we consider a distributed agent population, representing e.g. firms
or individuals. Further, we build on a continuous opinion dynamics model with
bounded confidence (), which assumes that two agents only interact if
differences in their behaviour are less than . Interaction results in
more similarity of behaviour, i.e. convergence towards a common mean. This
framework is extended by two major concepts: (i) The agent's in-group
consisting of acquainted interaction partners is explicitly taken into account.
This leads to an effective agent behaviour reflecting that agents try to
continue to interact with past partners and thus to keep sufficiently close to
them. (ii) The in-group network structure changes over time, as agents can form
new links to other agents with sufficiently close effective behaviour or delete
links to agents no longer close in behaviour. Thus, our model provides a
feedback mechanism between the agents' behaviour and their in-group structure.
Studying its consequences by means of agent-based computer simulations, we find
that for narrow-minded agents (low ) the additional feedback helps to
find consensus more often, whereas for open-minded agents (high )
this does not hold. This counterintuitive result is explained by simulations of
the network evolution
Cooperation sustainability in small groups:Exogenous and endogenous dynamics of the sustainability of cooperation
Cooperation sustainability presents a complex social phenomenon. Two common approaches have been used to study the sustainability of cooperation in small groups: endogenous processes (dynamic) and exogenous factors (static approaches). The present study integrates existing research by investigating how the interplay between exogenous and endogenous conditions affects cooperation in small groups. To uncover endogenous group dynamics in an online Public Goods experiment (n = 353), we performed multilevel latent Markov models on Bayesian estimation that allowed us to estimate latent classes on the level of rounds, individuals, and groups. We studied exogenous factors by investigating the effects of situational tightness versus looseness, and monetary versus symbolic frames on cooperation sustainability. Our key findings show that both endogenous and exogenous factors are critical to explain the variation of cooperation sustainability between groups. Second, groups exposed to tight situations reveal higher levels of cooperation sustainability than groups exposed to loose situations. Money primes did not have an impact. Among the control variables, collective intentionality showed the strongest association with cooperation. Future research may develop a more sophisticated measure of tight versus loose situations and examine the causal relationship between collective intentionality and cooperation
Aspiration Dynamics of Multi-player Games in Finite Populations
Studying strategy update rules in the framework of evolutionary game theory,
one can differentiate between imitation processes and aspiration-driven
dynamics. In the former case, individuals imitate the strategy of a more
successful peer. In the latter case, individuals adjust their strategies based
on a comparison of their payoffs from the evolutionary game to a value they
aspire, called the level of aspiration. Unlike imitation processes of pairwise
comparison, aspiration-driven updates do not require additional information
about the strategic environment and can thus be interpreted as being more
spontaneous. Recent work has mainly focused on understanding how aspiration
dynamics alter the evolutionary outcome in structured populations. However, the
baseline case for understanding strategy selection is the well-mixed population
case, which is still lacking sufficient understanding. We explore how
aspiration-driven strategy-update dynamics under imperfect rationality
influence the average abundance of a strategy in multi-player evolutionary
games with two strategies. We analytically derive a condition under which a
strategy is more abundant than the other in the weak selection limiting case.
This approach has a long standing history in evolutionary game and is mostly
applied for its mathematical approachability. Hence, we also explore strong
selection numerically, which shows that our weak selection condition is a
robust predictor of the average abundance of a strategy. The condition turns
out to differ from that of a wide class of imitation dynamics, as long as the
game is not dyadic. Therefore a strategy favored under imitation dynamics can
be disfavored under aspiration dynamics. This does not require any population
structure thus highlights the intrinsic difference between imitation and
aspiration dynamics
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