Cooperation with dynamic asymmetric evaluation in complex networks from a risk perspective.

The choice of strategy exposes individuals to the risk of betrayal. This induces individuals' irrational tendencies in strategy selection, which further influences the emergence of cooperative behavior. However, the underlying mechanisms connecting risk perception and the emergence of cooperation are still not fully understood. To address this, the classic evolutionary game model on complex networks is extended. We depict the interaction between strategy imitation and payoff evaluation from two perspectives: dynamic adjustment and irrational assessment. Specifically, the probability distortion involved in the dynamic selection of imitative reference points, as well as the asymmetric psychological utility associated with reference point dependence, is emphasized. Monte Carlo simulations demonstrate that individual irrational cognition induced by the risk of strategy selection can promote the emergence of cooperative behavior. Among them, the risk sensitivity within psychological utility has the most significant moderating effect. Moreover, the promoting effect of strong heterogeneity and high clustering in the network topology on cooperation under risk scenarios has been clarified. Additionally, the influence of initial states on the emergence of cooperation follows a step-like pattern. This research offers valuable insights for further exploring the cooperation mechanisms among irrational agents, even in scenarios involving the regulation of group cooperation behavior in risky situations.

Evolutionary dynamics of cooperation with the celebrity effect in complex networks.

How long-term cooperation is maintained in a society is an important and interesting question. The evolutionary game theory is often used as the basic framework to study this topic. The social status of game participants has an important influence on individual decision-making. Enlightened by this thought, we present a classification imitation model where the mechanisms of the celebrity effect and incomplete egoism are presented. The celebrity effect is reflected in each strategy update process to probe how individual decision-making is dynamically adjusted by comparing the social status of both parties in the game. The incomplete egoism refers to the irrational imitation of celebrities while self-interest is ignored. With this model, the group cooperation decision-making mechanism led by celebrities is revealed. Large-scale Monte Carlo simulations show that the incomplete egoism of individuals cannot stimulate cooperation but guarantee the stable existence of cooperation. Furthermore, the scale-free and community structure of the network enables cooperation to spread widely and maintains long-term survival. Our conclusion might provide practically new insight into the understanding and controlling of cooperation in the complex social systems.

Investment preference promotes cooperation in spatial public goods game.

It is usually assumed that each cooperator contributes equally to different public pools in spatial public goods game. However, it is more reasonable to invest differently according to individual investment preference. In this paper, an extended public goods game, in which cooperators contribute to the groups according to the investment preference, is developed. The investment preference of a cooperator is characterized by the fraction of the cooperator from his/her own memory about a group and the intensity of investment preference is represented by a tunable parameter α. The well-mixed population and the structured population are analyzed under this mechanism. It is shown that the investment preference can give rise to coordination. Moreover, the extensive numerical simulation results show that with the increasing of investment preference density or memory length, the proportion of cooperation can increase monotonously. This is because the investment preference could help cooperators resist the invasion from defectors. Compared with the basic version, the new mechanism is able to promote cooperation effectively. Our research may provide a valuable insight for further exploring the nature of cooperation in the real world.

Coevolution of teaching ability and cooperation in spatial evolutionary games.

Individuals with higher reputation are able to spread their social strategies easily. At the same time, one's reputation is changing according to his previous behaviors, which leads to completely different teaching abilities for players. To explore the effect of the teaching ability influenced by reputation, we consider a coevolutionary model in which the reputation score affects the updating rule in spatial evolutionary games. More precisely, the updating probability becomes bigger if his/her partner has a positive reputation. Otherwise, the updating probability becomes smaller. This simple design describes the influence of teaching ability on strategy adoption effectively. Numerical results focus on the proportion of cooperation under different levels of the amplitude of change of reputation and the range of reputation. For this dynamics, the fraction of cooperators presents a growth trend within a wide range of parameters. In addition, to validate the generality of this mechanism, we also employ the snowdrift game. Moreover, the evolution of cooperation on Erdos-Rényi random graph is studied for the prisoner's dilemma game. Our results may be conducive to understanding the emergence and sustainability of cooperation during the strategy adoptions in reality.

Surface-mode model of the extraordinary optical transmission without plasmons.

We propose a microscopic surface-mode model for the extraordinary optical transmission (EOT) through subwavelength metallic slit array covered with a thin dielectric layer under illumination of transverse-electric (TE) polarization. Remarkably, surface plasmon polarizations (SPPs) do not exist for this polarization. It is commonly believed that the waveguide mode in the dielectric layer plays a role similar to that of the SPP in classical EOT. To check the intuitive belief, we derive a surface-mode model by considering the multiple scattering process of the fundamental waveguide mode and neglecting all other residual field in the thin dielectric layer. The model captures the main feature of EOT and provides a phase-matching condition to predict the transmission resonance. Quantitative comparison between fully-vectorial calculations and model predictions shows that besides the fundamental waveguide mode, other residual field in the thin dielectric layer also contributes to the EOT without SPP.