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11.
Logistic operator - fundamental factor in rational production of services in multimodal transport
Ratko Zelenika, Drago Sever, Sabina Kamnik Zebec, Bojan Pirš, 2005, pregledni znanstveni članek

Opis: From its theoretical and practical point of view, traffic is one of the fundamental factors of the economy in a state. In the developed European countries, a rational production of transport services is presented by multimodal transport and the correct selection of a logistic operator. The aim of multimodal transport is to link together different forms of traffic in the most effective way, as well as all operations considering transport. The logistic operator is the only professional to perform complete services in multimodal transport, therefore it was necesarry to enable its further development and, in accordance with that, to suggest suitable solutions. An increase of the existing and the creation of new traffic currents can only be achieved with the development of multimodal transport, the correct selection of logistic operator and better organisation of the traffic system. In the future, the Republic of Slovenia should continue developing multimodal transport in order to decrease the differences in forms of transport in the developed European countries in the shortest time possible.The main task of the Republic of Slovenia is to integrate into the European flows as soon as possible, engage in a reciprocal cooperation by liberalization of flows of commodities and services, and create conditions for the inflow of foreign capital where all advantages of multimodal transport come into consideration. The result of the research is a model of multimodal transport logistic operator connecting the basic elements of that transport.
Ključne besede: logistical operator, rationalization, multimodal infrastructure, multimodal suprastructure, multimodal technologies, multimodal movement of goods, logistical information systems
Objavljeno: 02.06.2017; Ogledov: 379; Prenosov: 25
.pdf Celotno besedilo (5,25 MB)
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12.
Evolution of conditional cooperation under multilevel selection
Huanren Zhang, Matjaž Perc, 2016, izvirni znanstveni članek

Opis: We study the emergence of conditional cooperation in the presence of both intra-group and inter-group selection. Individuals play public goods games within their groups using conditional strategies, which are represented as piecewise linear response functions. Accordingly, groups engage in conflicts with a certain probability. In contrast to previous studies, we consider continuous contribution levels and a rich set of conditional strategies, allowing for a wide range of possible interactions between strategies. We find that the existence of conditional strategies enables the stabilization of cooperation even under strong intra-group selection. The strategy that eventually dominates in the population has two key properties: (i) It is unexploitable with strong intra-group selection; (ii) It can achieve full contribution to outperform other strategies in the inter-group selection. The success of this strategy is robust to initial conditions as well as changes to important parameters. We also investigate the influence of different factors on cooperation levels, including group conflicts, group size, and migration rate. Their effect on cooperation can be attributed to and explained by their influence on the relative strength of intra-group and inter-group selection.
Ključne besede: conditional cooperation, public goods, multilevel selection, physics of social systems
Objavljeno: 23.06.2017; Ogledov: 195; Prenosov: 167
.pdf Celotno besedilo (1,65 MB)
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13.
Excessive abundance of common resources deters social responsibility
Xiaojie Chen, Matjaž Perc, 2014, izvirni znanstveni članek

Opis: We study the evolution of cooperation in the collective-risk social dilemma game, where the risk is determined by a collective target that must be reached with individual contributions. All players initially receive endowments from the available amount of common resources. While cooperators contribute part of their endowment to the collective target, defectors do not. If the target is not reached, the endowments of all players are lost. In our model, we introduce a feedback between the amount of common resources and the contributions of cooperators. We show that cooperation can be sustained only if the common resources are preserved but never excessively abound. This, however, requires a delicate balance between the amount of common resources that initially exist, and the amount cooperators contribute to the collective target. Exceeding critical thresholds in either of the two amounts leads to loss of cooperation, and consequently to the depletion of common resources.
Ključne besede: social dilemma, evolutionary games, public goods, abundance, phase transitions, physics of social systems
Objavljeno: 23.06.2017; Ogledov: 379; Prenosov: 170
.pdf Celotno besedilo (950,12 KB)
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14.
If players are sparse social dilemmas are too: importance of percolation for evolution of cooperation
Zhen Wang, Attila Szolnoki, Matjaž Perc, 2012, izvirni znanstveni članek

Opis: Spatial reciprocity is a well known tour de force of cooperation promotion. A thorough understanding of the effects of different population densities is therefore crucial. Here we study the evolution of cooperation in social dilemmas on different interaction graphs with a certain fraction of vacant nodes. We find that sparsity may favor the resolution of social dilemmas, especially if the population density is close to the percolation threshold of the underlying graph. Regardless of the type of the governing social dilemma as well as particularities of the interaction graph, we show that under pairwise imitation the percolation threshold is a universal indicator of how dense the occupancy ought to be for cooperation to be optimally promoted. We also demonstrate that myopic updating, due to the lack of efficient spread of information via imitation, renders the reported mechanism dysfunctional, which in turn further strengthens its foundations.
Ključne besede: cooperation, public goods, punishment, phase transitions, physics of social systems
Objavljeno: 23.06.2017; Ogledov: 296; Prenosov: 156
.pdf Celotno besedilo (413,53 KB)
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15.
Interdependent network reciprocity in evolutionary games
Zhen Wang, Attila Szolnoki, Matjaž Perc, 2013, izvirni znanstveni članek

Opis: Besides the structure of interactions within networks, also the interactions between networks are of the outmost importance. We therefore study the outcome of the public goods game on two interdependent networks that are connected by means of a utility function, which determines how payoffs on both networks jointly influence the success of players in each individual network. We show that an unbiased coupling allows the spontaneous emergence of interdependent network reciprocity, which is capable to maintain healthy levels of public cooperation even in extremely adverse conditions. The mechanism, however, requires simultaneous formation of correlated cooperator clusters on both networks. If this does not emerge or if the coordination process is disturbed, network reciprocity fails, resulting in the total collapse of cooperation. Network interdependence can thus be exploited effectively to promote cooperation past the limits imposed by isolated networks, but only if the coordination between the interdependent networks is not disturbed.
Ključne besede: social dilemma, cooperation, public goods, biased utility, interdependent networks, statistical physics of social systems
Objavljeno: 23.06.2017; Ogledov: 306; Prenosov: 166
.pdf Celotno besedilo (741,04 KB)
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16.
Leaders should not be conformists in evolutionary social dilemmas
Attila Szolnoki, Matjaž Perc, 2016, izvirni znanstveni članek

Opis: The most common assumption in evolutionary game theory is that players should adopt a strategy that warrants the highest payoff. However, recent studies indicate that the spatial selection for cooperation is enhanced if an appropriate fraction of the population chooses the most common rather than the most profitable strategy within the interaction range. Such conformity might be due to herding instincts or crowd behavior in humans and social animals. In a heterogeneous population where individuals differ in their degree, collective influence, or other traits, an unanswered question remains who should conform. Selecting conformists randomly is the simplest choice, but it is neither a realistic nor the optimal one. We show that, regardless of the source of heterogeneity and game parametrization, socially the most favorable outcomes emerge if the masses conform. On the other hand, forcing leaders to conform significantly hinders the constructive interplay between heterogeneity and coordination, leading to evolutionary outcomes that are worse still than if conformists were chosen randomly. We conclude that leaders must be able to create a following for network reciprocity to be optimally augmented by conformity. In the opposite case, when leaders are castrated and made to follow, the failure of coordination impairs the evolution of cooperation.
Ključne besede: cooperation, public goods, selection, physics of social systems
Objavljeno: 23.06.2017; Ogledov: 192; Prenosov: 175
.pdf Celotno besedilo (620,37 KB)
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17.
Optimal interdependence between networks for the evolution of cooperation
Zhen Wang, Attila Szolnoki, Matjaž Perc, 2013, izvirni znanstveni članek

Opis: Recent research has identified interactions between networks as crucial for the outcome of evolutionary games taking place on them. While the consensus is that interdependence does promote cooperation by means of organizational complexity and enhanced reciprocity that is out of reach on isolated networks, we here address the question just how much interdependence there should be. Intuitively, one might assume the more the better. However, we show that in fact only an intermediate density of sufficiently strong interactions between networks warrants an optimal resolution of social dilemmas. This is due to an intricate interplay between the heterogeneity that causes an asymmetric strategy flow because of the additional links between the networks, and the independent formation of cooperative patterns on each individual network. Presented results are robust to variations of the strategy updating rule, the topology of interdependent networks, and the governing social dilemma, thus suggesting a high degree of universality.
Ključne besede: social dilemma, cooperation, public goods, biased utility, interdependent networks, statistical physics of social systems
Objavljeno: 23.06.2017; Ogledov: 305; Prenosov: 175
.pdf Celotno besedilo (658,72 KB)
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18.
Spreading of cooperative behaviour across interdependent groups
Luo-Luo Jiang, Matjaž Perc, 2013, izvirni znanstveni članek

Opis: Recent empirical research has shown that links between groups reinforce individuals within groups to adopt cooperative behaviour. Moreover, links between networks may induce cascading failures, competitive percolation, or contribute to efficient transportation. Here we show that there in fact exists an intermediate fraction of links between groups that is optimal for the evolution of cooperation in the prisoners dilemma game. We consider individual groups with regular, random, and scale-free topology, and study their different combinations to reveal that an intermediate interdependence optimally facilitates the spreading of cooperative behaviour between groups. Excessive between-group links simply unify the two groups and make them act as one, while too rare between-group links preclude a useful information flow between the two groups. Interestingly, we find that between-group links are more likely to connect two cooperators than in-group links, thus supporting the conclusion that they are of paramount importance.
Ključne besede: social dilemma, cooperation, public goods, biased utility, interdependent networks, statistical physics of social systems
Objavljeno: 23.06.2017; Ogledov: 594; Prenosov: 166
.pdf Celotno besedilo (665,03 KB)
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19.
Sustainable institutionalized punishment requires elimination of second-order free-riders
Matjaž Perc, 2012, izvirni znanstveni članek

Opis: Although empirical and theoretical studies affirm that punishment can elevate collaborative efforts, its emergence and stability remain elusive. By peer-punishment the sanctioning is something an individual elects to do depending on the strategies in its neighborhood. The consequences of unsustainable efforts are therefore local. By pool-punishment, on the other hand, where resources for sanctioning are committed in advance and at large, the notion of sustainability has greater significance. In a population with free-riders, punishers must be strong in numbers to keep the "punishment pool" from emptying. Failure to do so renders the concept of institutionalized sanctioning futile. We show that pool-punishment in structured populations is sustainable, but only if second-order free-riders are sanctioned as well, and to a such degree that they cannot prevail. A discontinuous phase transition leads to an outbreak of sustainability when punishers subvert second-order free-riders in the competition against defectors.
Ključne besede: cooperation, public goods, punishment, institutions, phase transitions, physics of social systems
Objavljeno: 23.06.2017; Ogledov: 416; Prenosov: 157
.pdf Celotno besedilo (469,23 KB)
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20.
Wisdom of groups promotes cooperation in evolutionary social dilemmas
Attila Szolnoki, Zhen Wang, Matjaž Perc, 2012, izvirni znanstveni članek

Opis: Whether or not to change strategy depends not only on the personal success of each individual, but also on the success of others. Using this as motivation, we study the evolution of cooperation in games that describe social dilemmas, where the propensity to adopt a different strategy depends both on individual fitness as well as on the strategies of neighbors. Regardless of whether the evolutionary process is governed by pairwise or group interactions, we show that plugging into the wisdom of groups strongly promotes cooperative behavior. The more the wider knowledge is taken into account the more the evolution of defectors is impaired. We explain this by revealing a dynamically decelerated invasion process, by means of which interfaces separating different domains remain smooth and defectors therefore become unable to efficiently invade cooperators. This in turn invigorates spatial reciprocity and establishes decentralized decision making as very beneficial for resolving social dilemmas.
Ključne besede: cooperation, public goods, wisdom of crowds, phase transitions, physics of social systems
Objavljeno: 23.06.2017; Ogledov: 406; Prenosov: 143
.pdf Celotno besedilo (646,99 KB)
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