63,350 research outputs found
On the coexistence of cooperators, defectors and conditional cooperators in the multiplayer iterated Prisoner's Dilemma
Recent experimental evidence [Gruji\'c et al., PLoS ONE 5, e13749 (2010)] on
the spatial Prisoner's Dilemma suggests that players choosing to cooperate or
not on the basis of their previous action and the actions of their neighbors
coexist with steady defectors and cooperators. We here study the coexistence of
these three strategies in the multiplayer iterated Prisoner's Dilemma by means
of the replicator dynamics. We consider groups with n = 2, 3, 4 and 5 players
and compute the payoffs to every type of player as the limit of a Markov chain
where the transition probabilities between actions are found from the
corresponding strategies. We show that for group sizes up to n = 4 there exists
an interior point in which the three strategies coexist, the corresponding
basin of attraction decreasing with increasing number of players, whereas we
have not been able to locate such a point for n = 5. We analytically show that
in the infinite n limit no interior points can arise. We conclude by discussing
the implications of this theoretical approach on the behavior observed in
experiments.Comment: 12 pages, 10 figures, uses elsart.cl
Micromagnetic Simulation of Nanoscale Films with Perpendicular Anisotropy
A model is studied for the theoretical description of nanoscale magnetic
films with high perpendicular anisotropy. In the model the magnetic film is
described in terms of single domain magnetic grains with Ising-like behavior,
interacting via exchange as well as via dipolar forces. Additionally, the model
contains an energy barrier and a coupling to an external magnetic field.
Disorder is taken into account in order to describe realistic domain and domain
wall structures. The influence of a finite temperature as well as the dynamics
can be modeled by a Monte Carlo simulation.
Many of the experimental findings can be investigated and at least partly
understood by the model introduced above. For thin films the magnetisation
reversal is driven by domain wall motion. The results for the field and
temperature dependence of the domain wall velocity suggest that for thin films
hysteresis can be described as a depinning transition of the domain walls
rounded by thermal activation for finite temperatures.Comment: Revtex, Postscript Figures, to be published in J. Appl.Phy
No context, no content, no problem
Recently, philosophers have offered compelling reasons to think that demonstratives are best represented as variables, sensitive not to the context of utterance, but to a variable assignment. Variablists typically explain familiar intuitions about demonstrativesâintuitions that suggest that what is said by way of a demonstrative sentence varies systematically over contextsâby claiming that contexts initialize a particular assignment of values to variables. I argue that we do not need to link context and the assignment parameter in this way, and that we would do better not to
MAGNETISATION REVERSAL AND DOMAIN STRUCTURE IN THIN MAGNETIC FILMS: THEORY AND COMPUTER SIMULATION
A model is introduced for the theoretical description of nanoscale magnetic
films with high perpendicular anisotropy. In the model the magnetic film is
described in terms of single domain magnetic grains, interacting via exchange
as well as via dipolar forces. Additionally, the model contains anisotropy
energy and a coupling to an external magnetic field. Disorder is taken into
account in order to describe realistic domain and domain wall structures.
Within this framework the dependence of the energy on the film thickness can be
discussed. The influence of a finite temperature as well as the dynamics can be
modeled by a Monte Carlo simulation. The results on the hysteresis loops, the
domain configurations, and the dynamics during the reversal process are in good
agreement with experimental findings.Comment: 4 Pages, Postscript, uuencode
Is Inuktitut a morphological argument language?
In the following I will discuss grammatical structures of Inuktitut, an Eskimo language spoken in the Canadian Eastern Arctic. Inuktitut is a polysynthetic language exhibiting an exceedingly elaborate verbal inflectional system including polypersonal marking. Furthermore, Inuktitut features free word order and optionality of noun phrases crossreferenced with the predicate. But Inuktitut also exhibits a number of features which seem to contradict the possibility of its being a "pronominal argument language" -- or as I would prefer to express it, a morphological argument language
Asymptotic Consensus Without Self-Confidence
This paper studies asymptotic consensus in systems in which agents do not
necessarily have self-confidence, i.e., may disregard their own value during
execution of the update rule. We show that the prevalent hypothesis of
self-confidence in many convergence results can be replaced by the existence of
aperiodic cores. These are stable aperiodic subgraphs, which allow to virtually
store information about an agent's value distributedly in the network. Our
results are applicable to systems with message delays and memory loss.Comment: 13 page
The Burden of Choice, the Complexity of the World and Its Reduction: The Game of Go/Weiqi as a Practice of "Empirical Metaphysics
The main aim of the text is to show how a game of Go (Weiqi, baduk, Igo) can serve as a
model representation of the ontological-metaphysical aspect of the actorânetwork theory
(ANT). An additional objective is to demonstrate in return that this ontological-metaphysâ ical
aspect of ANT represented on Go/Weiqi game model is able to highlight the key
aspect of this theoryâonto-methodological praxis
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