3,947 research outputs found
Turnout Intention and Social Networks
How can networking affect the turnout in an election? We present a simple model to explain turnout as a result of a dynamic process of formation of the intention to vote within Erdös-Renyi random networks. Citizens have fixed preferences for one of two parties and are embedded in a given social network. They decide whether or not to vote on the basis of the attitude of their immediate contacts. They may simply follow the behavior of the majority (followers) or make an adaptive local calculus of voting (Downsian behavior). So they either have the intention of voting when the majority of their neighbors are willing to vote too, or they vote when they perceive in their social neighborhood that elections are "close". We study the long run average turnout, interpreted as the actual turnout observed in an election. Depending on the combination of values of the two key parameters, the average connectivity and the probability of behaving as a follower or in a Downsian fashion, the system exhibits monostability (zero turnout), bistability (zero turnout and either moderate or high turnout) or tristability (zero, moderate and high turnout). This means, in particular, that for a wide range of values of both parameters, we obtain realistic turnout rates, i.e. between 50% and 90%.turnout, social networks, adaptative behavior
Evolutionary game theory: Temporal and spatial effects beyond replicator dynamics
Evolutionary game dynamics is one of the most fruitful frameworks for
studying evolution in different disciplines, from Biology to Economics. Within
this context, the approach of choice for many researchers is the so-called
replicator equation, that describes mathematically the idea that those
individuals performing better have more offspring and thus their frequency in
the population grows. While very many interesting results have been obtained
with this equation in the three decades elapsed since it was first proposed, it
is important to realize the limits of its applicability. One particularly
relevant issue in this respect is that of non-mean-field effects, that may
arise from temporal fluctuations or from spatial correlations, both neglected
in the replicator equation. This review discusses these temporal and spatial
effects focusing on the non-trivial modifications they induce when compared to
the outcome of replicator dynamics. Alongside this question, the hypothesis of
linearity and its relation to the choice of the rule for strategy update is
also analyzed. The discussion is presented in terms of the emergence of
cooperation, as one of the current key problems in Biology and in other
disciplines.Comment: Review, 48 pages, 26 figure
Nonlinear wave propagation in disordered media
We briefly review the state-of-the-art of research on nonlinear wave propagation in
disordered media. The paper is intended to provide the non-specialist reader with a flavor
of this active field of physics. Firstly, a general introduction to the subject is made. We
describe the basic models and the ways to study disorder in connection with them.
Secondly, analytical and numerical techniques suitable for this purpose are outlined. We
summarize their features and comment on their respective advantages, drawbacks and
applicability conditions. Thirdly, the Nonlinear Klein-Gordon and Schrbdinger equations
are chosen as specific examples. We collect a number of results that are representative of
the phenomena arising from the competition between nonlinearity and disorder. The
review is concluded with some remarks on open questions, main current trends and
possible further developments.This work has been supported in part by the C.I.C. y T. (Spain) under project MAT90-0S44. A S. was also supported by fellowships from the Universidad Complutense and the Ministerio de Educacion y Ciencia.Publicad
Time Scales in Evolutionary Dynamics
Evolutionary game theory has traditionally assumed that all individuals in a
population interact with each other between reproduction events. We show that
eliminating this restriction by explicitly considering the time scales of
interaction and selection leads to dramatic changes in the outcome of
evolution. Examples include the selection of the inefficient strategy in the
Harmony and Stag-Hunt games, and the disappearance of the coexistence state in
the Snowdrift game. Our results hold for any population size and in the
presence of a background of fitness.Comment: Final version with minor changes, accepted for publication in
Physical Review Letter
Physics of human cooperation: experimental evidence and theoretical models
In recent years, many physicists have used evolutionary game theory combined with a complex systems perspective in an attempt to understand social phenomena and challenges. Prominent among such phenomena is the issue of the emergence and sustainability of cooperation in a networked world of selfish or self-focused individuals. The vast majority of research done by physicists on these questions is theoretical, and is almost always posed in terms of agent-based models. Unfortunately, more often than not such models ignore a number of facts that are well established experimentally, and are thus rendered irrelevant to actual social applications. I here summarize some of the facts that any realistic model should incorporate and take into account, discuss important aspects underlying the relation between theory and experiments, and discuss future directions for research based on the available experimental knowledge.This work was partially supported by the EU through FET-Proactive Project DOLFINS (contract no. 640772) and FET-Open Project IBSEN (contract no. 662725), and by Ministerio de EconomÃa y Competitividad (Spain)/FEDER (EU) grant VARIANCE (contract no. FIS2015-64349-P). Project IBSEN is in fact about large-scale experiments and provides a open-access platform for researchers to carry out them
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