6,262 research outputs found
Asymmetric evolutionary games
Evolutionary game theory is a powerful framework for studying evolution in
populations of interacting individuals. A common assumption in evolutionary
game theory is that interactions are symmetric, which means that the players
are distinguished by only their strategies. In nature, however, the microscopic
interactions between players are nearly always asymmetric due to environmental
effects, differing baseline characteristics, and other possible sources of
heterogeneity. To model these phenomena, we introduce into evolutionary game
theory two broad classes of asymmetric interactions: ecological and genotypic.
Ecological asymmetry results from variation in the environments of the players,
while genotypic asymmetry is a consequence of the players having differing
baseline genotypes. We develop a theory of these forms of asymmetry for games
in structured populations and use the classical social dilemmas, the Prisoner's
Dilemma and the Snowdrift Game, for illustrations. Interestingly, asymmetric
games reveal essential differences between models of genetic evolution based on
reproduction and models of cultural evolution based on imitation that are not
apparent in symmetric games.Comment: accepted for publication in PLOS Comp. Bio
Evolutionary games on graphs
Game theory is one of the key paradigms behind many scientific disciplines
from biology to behavioral sciences to economics. In its evolutionary form and
especially when the interacting agents are linked in a specific social network
the underlying solution concepts and methods are very similar to those applied
in non-equilibrium statistical physics. This review gives a tutorial-type
overview of the field for physicists. The first three sections introduce the
necessary background in classical and evolutionary game theory from the basic
definitions to the most important results. The fourth section surveys the
topological complications implied by non-mean-field-type social network
structures in general. The last three sections discuss in detail the dynamic
behavior of three prominent classes of models: the Prisoner's Dilemma, the
Rock-Scissors-Paper game, and Competing Associations. The major theme of the
review is in what sense and how the graph structure of interactions can modify
and enrich the picture of long term behavioral patterns emerging in
evolutionary games.Comment: Review, final version, 133 pages, 65 figure
Evolutionary games and quasispecies
We discuss a population of sequences subject to mutations and
frequency-dependent selection, where the fitness of a sequence depends on the
composition of the entire population. This type of dynamics is crucial to
understand the evolution of genomic regulation. Mathematically, it takes the
form of a reaction-diffusion problem that is nonlinear in the population state.
In our model system, the fitness is determined by a simple mathematical game,
the hawk-dove game. The stationary population distribution is found to be a
quasispecies with properties different from those which hold in fixed fitness
landscapes.Comment: 7 pages, 2 figures. Typos corrected, references updated. An exact
solution for the hawks-dove game is provide
Evolutionary Games and Computer Simulations
The prisoner's dilemma has long been considered the paradigm for studying the
emergence of cooperation among selfish individuals. Because of its importance,
it has been studied through computer experiments as well as in the laboratory
and by analytical means. However, there are important differences between the
way a system composed of many interacting elements is simulated by a digital
machine and the manner in which it behaves when studied in real experiments. In
some instances, these disparities can be marked enough so as to cast doubt on
the implications of cellular automata type simulations for the study of
cooperation in social systems. In particular, if such a simulation imposes
space-time granularity, then its ability to describe the real world may be
compromised. Indeed, we show that the results of digital simulations regarding
territoriality and cooperation differ greatly when time is discrete as opposed
to continuous.Comment: 8 pages. Also available through anonymous ftp from parcftp.xerox.com
in the directory /pub/dynamics as pdilemma.p
Phase Transition in Evolutionary Games
The evolution of cooperative behaviour is studied in the deterministic
version of the Prisoners' Dilemma on a two-dimensional lattice. The payoff
parameter is set at the critical region , where clusters of
cooperators are formed in all spatial sizes. Using the factorial moments
developed in particle and nuclear physics for the study of phase transition,
the distribution of cooperators is studied as a function of the bin size
covering varying numbers of lattice cells. From the scaling behaviour of the
moments a scaling exponent is determined and is found to lie in the range where
phase transitions are known to take place in physical systems. It is therefore
inferred that when the payoff parameter is increased through the critical
region the biological system of cooperators undergoes a phase transition to
defectors. The universality of the critical behaviour is thus extended to
include also this particular model of evolution dynamics.Comment: 12 pages + 3 figures, latex, submitted to Natur
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