1. Evolution of interactions and cooperation in the spatial prisoner's dilemma gameChunyan Zhang, Jianlei Zhang, Guangming Xie, Long Wang, Matjaž Perc, 2011, izvirni znanstveni članek Opis: We study the evolution of cooperation in the spatial prisoner's dilemma game where players are allowed to establish new interactions with others. By employing a simple coevolutionary rule entailing only two crucial parameters, we find that different selection criteria for the new interaction partners as well as their number vitally affect the outcome of the game. The resolution of the social dilemma is most probable if the selection favors more successful players and if their maximally attainable number is restricted. While the preferential selection of the best players promotes cooperation irrespective of game parametrization, the optimal number of new interactions depends somewhat on the temptation to defect. Our findings reveal that the "making of new friends" may be an important activity for the successful evolution of cooperation, but also that partners must be selected carefully and their number limited. Ključne besede: evolutionary games, prisoner's dilemma, coevolution, complex networks, friendship Objavljeno: 19.06.2017; Ogledov: 207; Prenosov: 176 Celotno besedilo (309,95 KB) Gradivo ima več datotek! Več...

2. Coevolution of quantum and classical strategies on evolving random networksQiang Li, Azhar Iqbal, Matjaž Perc, Minyou Chen, Derek Abbott, 2013, izvirni znanstveni članek Opis: We study the coevolution of quantum and classical strategies on weighted and directed random networks in the realm of the prisoners dilemma game. During the evolution, agents can break and rewire their links with the aim of maximizing payoffs, and they can also adjust the weights to indicate preferences, either positive or negative, towards their neighbors. The network structure itself is thus also subject to evolution. Importantly, the directionality of links does not affect the accumulation of payoffs nor the strategy transfers, but serves only to designate the owner of each particular link and with it the right to adjust the link as needed. We show that quantum strategies outperform classical strategies, and that the critical temptation to defect at which cooperative behavior can be maintained rises, if the network structure is updated frequently. Punishing neighbors by reducing the weights of their links also plays an important role in maintaining cooperation under adverse conditions. We find that the selforganization of the initially random network structure, driven by the evolutionary competition between quantum and classical strategies, leads to the spontaneous emergence of small average path length and a large clustering coefficient. Ključne besede: evolutionary games, quantum strategies, coevolution, random networks, cooperation Objavljeno: 19.06.2017; Ogledov: 304; Prenosov: 156 Celotno besedilo (803,96 KB) Gradivo ima več datotek! Več...

3. Different reactions to adverse neighborhoods in games of cooperationChunyan Zhang, Jianlei Zhang, Franz Weissing, Matjaž Perc, Guangming Xie, Long Wang, 2012, izvirni znanstveni članek Opis: In social dilemmas, cooperation among randomly interacting individuals is often difficult to achieve. The situation changes if interactions take place in a network where the network structure jointly evolves with the behavioral strategies of the interacting individuals. In particular, cooperation can be stabilized if individuals tend to cut interaction links when facing adverse neighborhoods. Here we consider two different types of reaction to adverse neighborhoods, and all possible mixtures between these reactions. When faced with a gloomy outlook, players can either choose to cut and rewire some of their links to other individuals, or they can migrate to another location and establish new links in the new local neighborhood. We find that in general local rewiring is more favorable for the evolution of cooperation than emigration from adverse neighborhoods. Rewiring helps to maintain the diversity in the degree distribution of players and favors the spontaneous emergence of cooperative clusters. Both properties are known to favor the evolution of cooperation on networks. Interestingly, a mixture of migration and rewiring is even more favorable for the evolution of cooperation than rewiring on its own. While most models only consider a single type of reaction to adverse neighborhoods, the coexistence of several such reactions may actually be an optimal setting for the evolution of cooperation. Ključne besede: cooperation, public goods, phase transitions, social dilemmas, coevolution, physics of social systems Objavljeno: 19.06.2017; Ogledov: 421; Prenosov: 180 Celotno besedilo (481,90 KB) Gradivo ima več datotek! Več...

4. Effects of adaptive degrees of trust on coevolution of quantum strategies on scalefree networksQiang Li, Minyou Chen, Matjaž Perc, Azhar Iqbal, Derek Abbott, 2013, izvirni znanstveni članek Opis: We study the impact of adaptive degrees of trust on the evolution of cooperation in the quantum prisoner's dilemma game. In addition to the strategies, links between players are also subject to evolution. Starting with a scalefree interaction network, players adjust trust towards their neighbors based on received payoffs. The latter governs the strategy adoption process, while trust governs the rewiring of links. As soon as the degree of trust towards a neighbor drops to zero, the link is rewired to another randomly chosen player within the network. We find that for small temptations to defect cooperators always dominate, while for intermediate and strong temptations a single quantum strategy is able to outperform all other strategies. In general, reciprocal trust remains within close relationships and favors the dominance of a single strategy. Due to coevolution, the powerlaw degree distributions transform to Poisson distributions. Ključne besede: evolutionary games, quantum strategies, coevolution, random networks, cooperation, statistical physics of social systems Objavljeno: 23.06.2017; Ogledov: 195; Prenosov: 153 Celotno besedilo (669,03 KB) Gradivo ima več datotek! Več...

5. Coevolution of teaching activity promotes cooperationAttila Szolnoki, Matjaž Perc, 2008, izvirni znanstveni članek Opis: Evolutionary games are studied where the teaching activity of players can evolve in time. Initially all players following either the cooperative or defecting strategy are distributed on a square lattice. The rate of strategy adoption is determined by the payoff difference and a teaching activity characterizing the donor's capability to enforce its strategy on the opponent. Each successful strategy adoption process is accompanied by an increase in the donor's teaching activity. By applying an optimum value of the increment, this simple mechanism spontaneously creates relevant inhomogeneities in the teaching activities that support the maintenance of cooperation for both the prisoner's dilemma and the snowdrift game. Ključne besede: evolutionary game theory, prisoner's dilemma, spatial games, snowdrift game, coevolution Objavljeno: 30.06.2017; Ogledov: 269; Prenosov: 176 Celotno besedilo (521,01 KB) Gradivo ima več datotek! Več...

6. Emergence of multilevel selection in the prisoner's dilemma game on coevolving random networksAttila Szolnoki, Matjaž Perc, 2009, izvirni znanstveni članek Opis: We study the evolution of cooperation in the prisoner's dilemma game, whereby a coevolutionary rule is introduced that molds the random topology of the interaction network in two ways. First, existing links are deleted whenever a player adopts a new strategy or its degree exceeds a threshold value; second, new links are added randomly after a given number of game iterations. These coevolutionary processes correspond to the generic formation of new links and deletion of existing links that, especially in human societies, appear frequently as a consequence of ongoing socialization, change of lifestyle or death. Due to the counteraction of deletions and additions of links the initial heterogeneity of the interaction network is qualitatively preserved, and thus cannot be held responsible for the observed promotion of cooperation. Indeed, the coevolutionary rule evokes the spontaneous emergence of a powerful multilevel selection mechanism, which despite the sustained random topology of the evolving network, maintains cooperation across the whole span of defection temptation values. Ključne besede: evolutionary game theory, prisoner's dilemma, spatial games, coevolution, social systems Objavljeno: 30.06.2017; Ogledov: 525; Prenosov: 178 Celotno besedilo (627,32 KB) Gradivo ima več datotek! Več...

7. Fast random rewiring and strong connectivity impair subthreshold signal detection in excitable networksVladislav Volman, Matjaž Perc, 2010, izvirni znanstveni članek Opis: We study dynamical responses in locally paced networks consisting of diffusively coupled excitable units with dynamically adjusted connectivity. It is shown that for weak subthreshold pacing, excessive or strong connectivity impairs the reliable response of a network to the stimulus. Fast random dynamic rewiring of the network also acts detrimentally on signal detection by enforcing a faster relaxation upon the paced unit. Our results indicate that efficient signal processing on excitable complex networks requires tight correspondence between the dynamics of connectivity and the dynamical processes taking place on the network. This, in turn, suggests the existence of 'functionfollowsform' principles for systems described within this framework. Ključne besede: neuronal dynamics, complex networks, coevolution, cognition Objavljeno: 03.07.2017; Ogledov: 325; Prenosov: 148 Celotno besedilo (1,36 MB) 
8. Selforganization towards optimally interdependent networks by means of coevolutionZhen Wang, Attila Szolnoki, Matjaž Perc, 2014, izvirni znanstveni članek Opis: Coevolution between strategy and network structure is established as a means to arrive at the optimal conditions needed to resolve social dilemmas. Yet recent research has highlighted that the interdependence between networks may be just as important as the structure of an individual network. We therefore introduce the coevolution of strategy and network interdependence to see whether this can give rise to elevated levels of cooperation in the prisonerʼs dilemma game. We show that the interdependence between networks selforganizes so as to yield optimal conditions for the evolution of cooperation. Even under extremely adverse conditions, cooperators can prevail where on isolated networks they would perish. This is due to the spontaneous emergence of a twoclass society, with only the upper class being allowed to control and take advantage of the interdependence. Spatial patterns reveal that cooperators, once arriving at the upper class, are much more competent than defectors in sustaining compact clusters of followers. Indeed, the asymmetric exploitation of interdependence confers to them a strong evolutionary advantage that may resolve even the toughest of social dilemmas. Ključne besede: coevolution, cooperation, interdependent networks, evolutionary games, collective phenomena, selforganization, phase transitions, physics of social systems Objavljeno: 03.07.2017; Ogledov: 312; Prenosov: 156 Celotno besedilo (887,51 KB) Gradivo ima več datotek! Več...
