36 research outputs found
Quasi-stationary states of game-driven systems: a dynamical approach
Evolutionary game theory is a framework to formalize the evolution of
collectives ("populations") of competing agents that are playing a game and,
after every round, update their strategies to maximize individual payoffs.
There are two complementary approaches to modeling evolution of player
populations. The first addresses essentially finite populations by implementing
the apparatus of Markov chains. The second assumes that the populations are
infinite and operates with a system of mean-field deterministic differential
equations. By using a model of two antagonistic populations, which are playing
a game with stationary or periodically varying payoffs, we demonstrate that it
exhibits metastable dynamics that is reducible neither to an immediate
transition to a fixation (extinction of all but one strategy in a finite-size
population) nor to the mean-field picture. In the case of stationary payoffs,
this dynamics can be captured with a system of stochastic differential
equations and interpreted as a stochastic Hopf bifurcation. In the case of
varying payoffs, the metastable dynamics is much more complex than the dynamics
of the means
Mutual synchronization of oscillations in a system of coupled evolutionary games
The purpose of this study is to investigate collective dynamics of coupled communities that evolve according to the population game «Battle of the Sexes». A separate community includes two interacting populations of players of opposite sex, where each player has one of two possible competing behavior strategies. It is necessary to determine the possibility of mutual synchronization of oscillations in the number of players adhering to a particular strategy, build a synchronization region, and also evaluate the dependence of the properties of oscillations on the coupling strength. Methods. In this paper, we study the system of evolutionary games «Battle of the Sexes» interacting through migration. To simulate the evolutionary game dynamics we make use of the stochastic Moran process, as well as the Monte Carlo method to sample game trajectories. Mutual synchronization is defined by the appropriately generalized criteria of frequency and phase locking. Results. It is shown that the system of coupled evolutionary games «Battle of the Sexes» demonstrates mutual synchronization of oscillations under sufficiently strong coupling. In particular, oscillation frequencies of two communities get adjusted to each other and begin to coincide at some interaction parameter, while the oscillations themselves become almost identical. A similar result was also observed for an ensemble of more than two communities. Conclusion. The dependence of the average frequencies of community oscillations on the coupling strength was determined, the adjustment of oscillations with an increase in the coupling strength was demonstrated, thereby showing the possibility of mutual synchronization in the model of coupled evolutionary games «Battle of the Sexes». The region of frequency synchronization was numerically found
Comparative statistical study of two local clustering coefficient formulations as tropical cyclone markers for climate networks
We introduce a new formulation of local clustering coefficient for weighted
correlation networks. This new formulation is based upon a definition
introduced previously in the neuroscience context and aimed at compensating for
spurious correlations caused by indirect interactions. We modify this
definition further by replacing Pearson's pairwise correlation coefficients and
three-way partial correlation coefficients by the respective Kendall's rank
correlations. This reduces statistical sample size requirements to compute the
correlations, which translates into the possibility of using shorter time
windows and hence into a shorter response time of the real-time climate network
analysis. We construct evolving climate networks of mean sea level pressure
fluctuations and analyze anomalies of local clustering coefficient in these
networks. We develop a broadly applicable statistical methodology to study
association between spatially inhomogeneous georeferenced multivariate time
series and binary-valued spatiotemporal data (or other data reducible to this
representation) and use it to compare the newly proposed formulation of local
clustering coefficient (for weighted correlation networks) to the conventional
one (for unweighted graphs) in terms of the association of these measures in
climate networks to tropical cyclones. Thus we substantiate the previously made
observation that tropical cyclones are associated with anomalously high values
of local clustering coefficient, and confirm that the new formulation shows a
stronger association
Solving the problem of credit defaults in retail sector
The article analyzes dynamics of the volume and annual rate of loan delinquency of the country’s population for intermediate quarter dates, compares default retail credit portfolios with similar portfolio of organizations, and determines the main reasons for appearance of population’s debts before banks. It is concluded that it is necessary for banks to focus on development of their own tools and technologies of payment recovery, related to determination of early problematic debt for the purpose of taking preventive measures for preventing the appearance of past-due debts, which is possible under the condition of investing money assets into own analytical and technological tools. An approach to segmentation of debts and factors that could be used as indicators in the process of accompanying and servicing of credits are offered.peer-reviewe
Dependence of progeny abundance for summer chum salmon (<i>Oncorhynchys keta</i>) in the Amur River on the parents abundance
For almost the century the landings of summer chum salmon in the Amur were approximately in 5 times lower that the landings of fall chum salmon, in spite on almost the same fishing efforts. However, its catches were very high in the 1990-2000s, even higher that for the fall chum salmon, that contradicts to conceptions on its lower absolute fecundity, smaller spawning grounds, and higher vulnerability of its reproduction on unfavorable external factors. Relationship of mature progeny abundance for summer chum salmon with number of their parents is analyzed. The data on the parents and progeny abundance were calculated from fishery statistics, including cited data, considering annual catch as 50 % of the stock. The highest recruitment of summer chum salmon is estimated as 19.08 · 106 ind. that is comparable with the strength of the fall chum salmon year-classes. The spawning stock of 1.94 · 106 ind. is enough to produce this progeny, but the population growth is much lower with the lower spawning stock, that is a real reason for slow recovery of the summer chum salmon stock, though potentially both races could be equally abundant. To maintain the stock of summer chum salmon at the highest level, an optimal number of parents should be passed to the spawning grounds, within rather narrow range, that is difficult to control in conditions of the big river
The Formation of Indicator Framework for Effective Assessment of Investment Attractiveness of the Region
Despite the in-depth study of many theoretical aspects of investment activities and assessment of investment attractiveness, today the impact of the investment policy on the development of an effective strategy and the formation of favorable investment climate is not properly reflected in the contemporary research. At the same time unstable situation in socio-economic development of Russia requires new approaches to the problem of investment activity. In this regard, the article provides indicator framework to assess properly the investment attractiveness of the region's economy relating to foreign direct investment in the current context. At that, the proposed indicator framework is based on a number of principles, which allow achieving the objective assessment of investment attractiveness of regions and feasibility of the concerned indicators.
Keywords: foreign direct investment, investment activity, investment climate, assessment of investment attractiveness, region's economy.
JEL Classifications: F21; F51; H77; O2