Motion of influential players can support cooperation in Prisoner’s Dilemma

We study a spatial Prisoner’s dilemma game with two types (A and B) of players located on a square lattice. Players following either cooperator or defector strategies play Prisoner’s Dilemma games with their 24 nearest neighbors. The players are allowed to adopt one of their neighbor’s strategy with a probability dependent on the payoff difference and type of the given neighbor. Players A and B have different efficiency in the transfer of their own strategies; therefore the strategy adoption probability is reduced by a multiplicative factor (w < 1) from the players of type B. We report that the motion of the influential payers (type A) can improve remarkably the maintenance of cooperation even for their low densities.     

Statistical physics of the spatial Prisoner’s Dilemma with memory-aware agents

We introduce an analytical model to study the evolution towards equilibrium in spatialgames, with ‘memory-aware’ agents, i.e., agents that accumulate their payoff over time. Inparticular, we focus our attention on the spatial Prisoner’s Dilemma, as it constitutes anemblematic example of a game whose Nash equilibrium is defection. Previous investigationsshowed that, under opportune conditions, it is possible to reach, in the evolutionaryPrisoner’s Dilemma, an equilibrium of cooperation. Notably, it seems that mechanisms likemotion may lead a population to become cooperative. In the proposed model, we map agentsto particles of a gas so that, on varying the system temperature, they randomly move. Indoing so, we are able to identify a relation between the temperature and the finalequilibrium of the population, explaining how it is possible to break the classical Nashequilibrium in the spatial Prisoner’s Dilemma when considering agents able to increasetheir payoff over time. Moreover, we introduce a formalism to study order-disorder phasetransitions in these dynamics. As result, we highlight that the proposed model allows toexplain analytically how a population, whose interactions are based on the Prisoner’sDilemma, can reach an equilibrium far from the expected one; opening also the way todefine a direct link between evolutionary game theory and statistical physics.     

Quantum Prisoner’s Dilemma in Asymmetric Strategy Spaces

International Journal of Theoretical Physics - Most games in the real world are asymmetric, and participants can have different conditions or strategies, depending on the available resources. In...     

On the Effect of Quantum Noise in a Quantum-Relativistic Prisoner’s Dilemma Cellular Automaton

The disrupting effect of quantum noise on the dynamics of a spatial quantum relativistic formulation of the iterated prisoner’s dilemma game with variable entangling is studied in this work. The game is played in the cellular automata manner, i.e., with local and synchronous interaction. The game is assessed in fair and unfair contests.     

A Quantum Relativistic Prisoner’s Dilemma Cellular Automaton

The effect of variable entangling on the dynamics of a spatial quantum relativistic formulation of the iterated prisoner’s dilemma game is studied in this work. The game is played in the cellular automata manner, i.e., with local and synchronous interaction. The game is assessed in fair and unfair contests.     

Payoff-based accumulative effect promotes cooperation in spatial prisoner’s dilemma

We study the effect of accumulative payoff on the evolution of cooperation in the evolutionary prisoner’s dilemma on a square lattice. We introduce a decaying factor for the accumulative payoff, which characterizes the extent that the historical payoff is accumulated. It is shown that for fixed values of the temptation to defect, the density of cooperators increases with the value of the decaying factor. This indicates that the more the historical payoff is involved, the more favourable cooperators become. In the critical region where the cooperator density converges to zero, cooperators vanish according to a power-law-like behaviour. The associated exponents agree approximately with the two-dimensional directed percolation and depend weakly on the value of the decaying factor.     

Adaptive co-evolution of strategies and network leading to optimal cooperation level in spatial prisoner’s dilemma game

We study evolutionary prisoner's dilemma game on adaptive networks where a population of players co-evolves with their interaction networks. During the co-evolution process, interacted players with opposite strategies either rewire the link between them with probability $p$ or update their strategies with probability $1-p$ depending on their payoffs. Numerical simulation shows that the final network is either split into some disconnected communities whose players share the same strategy within each community or forms a single connected network in which all nodes are in the same strategy. Interestingly, the density of cooperators in the final state can be maximised in an intermediate range of $p$ via the competition between time scale of the network dynamics and that of the node dynamics. Finally, the mean-field analysis helps to understand the results of numerical simulation. Our results may provide some insight into understanding the emergence of cooperation in the real situation where the individuals' behaviour and their relationship adaptively co-evolve.     

An indirect evidence of piezonuclear fission reactions: Geomechanical and geochemical evolution in the Earth’s crust

Piezonuclear reactions, which occur in inert and nonradioactive elements, are induced by high pressure and, in particular, by brittle fracture phenomena in solids under compression. These low energy reactions generally take place in nuclei with an atomic weight that is lower or equal to that of iron (Fe). The experimental evidence, obtained from repeatable measurements of neutron emissions, can be also recognized considering the anomalous chemical balances of the major events that have affected the Earth’s crust, oceans and atmosphere, over the last four billion years. These anomalies include: (i) the abrupt variations in the most abundant elements in correspondence to the formation of tectonic plates; (ii) the Great Oxidation Event (2.7 to 2.4 billion years ago), with a sharp increase in atmospheric oxygen and the subsequent origin of life; (iii) the increase of carbon and nytrogen concentrations in the primordial atmosphere.Natural piezonuclear reactions are induced by fault sliding and plate subduction phenomena.     

Effect of temperature on the evolution of bright and dark screening—photovoltaic spatial solitons

We investigate theoretically the temperature effects on the evolution of both bright and dark screening-photovoltaic optical spatial solitons in biased photovoltaic-photocefractive crystals in the case of neglecting the diffusion process.For a stable bright or dark screening-photovoltaic soliton originally formed in a crystal at a given temperature,when the crystal temperature changes,it will evolve into another stable screening-photovoltaic soliton if the change is quite small,whereas it will become unstable or break down if the temperature change is large enough.The spatial shape of a stable screening-photovoltaic soliton can be reshaped by appropriately adjusting the crystal temperature.     

Effects of information asymmetry on cooperation in the prisoners’ dilemma game

Effects of information asymmetry on cooperation in the prisoners’ dilemma game are investigated. The amplitude A is introduced to describe the degree of information asymmetry. It is found that there exists an optimal value of amplitude Aopt at which the fraction of cooperation reaches its maximal value. The reason lies in that cooperators on the two-dimensional grid form large clusters at Aopt . In addition, the theoretical analysis in terms of the meanfield theory is used to understand this kind of phenomenon. It is confirmed that the information asymmetry plays an important role in the dynamics of the dilemma games of spatial prisoners.     

Maxwell’s demon and the management of ignorance in stochastic thermodynamics

It is nearly 150 years since Maxwell challenged the validity of the second law of thermodynamics by imagining a tiny creature who could sort the molecules of a gas in such a way that would decrease entropy without exerting any work. The demon has been discussed largely using thought experiments, but it has recently become possible to exert control over nanoscale systems, just as Maxwell imagined, and the status of the second law has become a more practical matter, raising the issue of how measurements manage our ignorance in a way that can be exploited. The framework of stochastic thermodynamics extends macroscopic concepts such as heat, work, entropy and irreversibility to small systems and allows us explore the matter. Some arguments against a successful demon imply a second law that can be suspended indefinitely until we dissipate energy in order to remove the records of his operations. In contrast, under stochastic thermodynamics, the demon fails because on average, more work is performed upfront in making a measurement than can be extracted by exploiting the outcome. This requires us to exclude systems and a demon that evolve under what might be termed self-sorting dynamics, and we reflect on the constraints on control that this implies while still working within a thermodynamic framework.     

Penrose’s circles in the CMB and a test of inflation

We present a calculation of the angular size of the circles in the CMB predicted by Penrose on the basis of his conformal cyclic cosmology. If these circles are detected, the existence of an upper limit on their angular radius would provide a challenge for inflation.     

Cosmic rays and variations of the concentration of active nuclei of condensation and crystallization in the Earth’s atmosphere

A possible mechanism of the influence of cosmic rays on the concentration of neutral active nuclei of condensation and crystallization in the Earth’s atmosphere is considered. The mechanism is based on the variation in the transparency of the atmosphere under cosmic rays. It is shown that the concentration of active nuclei of condensation increase at low and middle altitudes, while the concentration of stable ice nuclei decreases. This effect and the change in the growth rate of drops can lead to correlation between the galactic cosmic rays and cloud cover anomalies at low altitudes and to the absence of correlation at middle altitudes. It is shown that the correlation between galactic cosmic rays and cloud cover anomalies can be absent at high altitudes.     

Temporal and spatial evolution of air-spark switch plasma investigated by the Mach–Zehnder interferometer

An air-spark switch plasma was diagnosed by the Mach–Zehnder laser interferometer with ultra-high spatial and temporal resolution. The interferograms containing plasma phase shift information at different time were obtained. The phase shift distributions of the plasma were extracted by numerically processing the interferograms. The three-dimensional(3 D) electron density distributions of the air-spark switch plasma were then obtained. The working process of the air-spark switch was described by analyzing the temporal and spatial evolution of the plasma electron density.     

Structure of two-loop evolution kernels and evolution of the pion wave function in ϕ(6)3 and QCD

The general structure of the two-loop nonforward evolution kernels is investigated in the ϕ₍₆₎³ model and QCD. The solution of the two-loop evolution equations is constructed in both models. In QCD, the contribution of the two-loop corrections to the wave function evolution is estimated numerically.