scholarly journals Coexisting with cheaters: Microbial exoenzyme production as a snowdrift game model

2021 ◽  
Author(s):  
Constantinos Xenophontos ◽  
Stanley Harpole ◽  
Kirsten Kuesel ◽  
Adam Clark
Keyword(s):  
Enzyme Production ◽  
Selection Process ◽  
Evolutionary Game ◽  
Stable States ◽  
Chemostat Model ◽  
The Public ◽  
Snowdrift Game ◽  
The Commons ◽  
Single Complex ◽  
Over Exploitation

Cheating in microbial communities is often regarded as a precursor to a “tragedy of the commons”, ultimately leading to over-exploitation by a few species, and destabilisation of the community. However, this view does not explain the ubiquity of cheaters in nature. Indeed, existing evidence suggests that cheaters are not only evolutionarily and ecologically inevitable, but also play important roles in communities, like promoting cooperative behaviour. We developed a chemostat model with two microbial species and a single, complex nutrient substrate. One of the organisms, an enzyme producer, degrades the substrate, releasing an essential and limiting resource that it can use both to grow and produce more enzymes, but at a cost. The second organism, a cheater, does not produce the enzyme but benefits from the diffused resource produced by the other species, allowing it to benefit from the public good, without contributing to it. We investigated evolutionarily stable states of coexistence between the two organisms and described how enzyme production rates and resource diffusion influence organism abundances. We found that, in the long-term evolutionary scale, monocultures of the producer drive themselves extinct because selection always favours mutant invaders that invest less in enzyme production. However, the presence of a cheater buffers this runaway selection process, preventing extinction of the producer and allowing coexistence. Resource diffusion rate controls cheater growth, preventing it from outcompeting the producer. These results show that competition from cheaters can force producers to maintain adequate enzyme production to sustain both itself and the cheater. This is known in evolutionary game theory as a “snowdrift game” – a metaphor describing a snow shoveler and a cheater following in their clean tracks. We move further to show that cheating can stabilise communities and possibly be a precursor to cooperation, rather than extinction.

scholarly journals Mining Pool Selection under Block WithHolding Attack

2021 ◽  
Vol 11 (4) ◽  
pp. 1617
Author(s):  
Kentaro Fujita ◽  
Yuanyu Zhang ◽  
Masahiro Sasabe ◽  
Shoji Kasahara
Keyword(s):  
Selection Process ◽  
Evolutionary Game ◽  
The Other ◽  
Stable States ◽  
Stable Pool ◽  
Critical Issues ◽  
Evolutionarily Stable ◽  
Pool Population

In current Proof-of-Work (PoW) blockchain systems, miners usually form mining pools to compete with other pools/miners in the mining competition. Forming pools can give miners steady revenues but will introduce two critical issues. One is mining pool selection, where miners select the pools to join in order to maximize their revenues. The other is a Block WithHolding (BWH) attack, where pools can inject part of their hash/mining power into other pools to obtain additional revenues without contributing to the mining process of the attacked pools. Reasoning that the BWH attack will have significant impacts on the pool selection, we therefore investigate the mining pool selection issue in the presence of a BWH attack in this paper. In particular, we model the pool selection process of miners as an evolutionary game and find the Evolutionarily Stable States (ESSs) of the game (i.e., stable pool population states) as the solutions. Previous studies investigated this problem from the perspective of pool managers and neglected the revenues from attacked pools (attacking revenues), leading to less accurate and insightful findings. This paper, however, focuses on the payoffs of miners and carefully takes the attacking revenues into consideration. To demonstrate how the problem is solved, we consider the scenario with two mining pools and further investigate the case where one pool attacks the other and the case where the two pools attack each other. The results in this paper show that pools can attract more miners to join by launching a BWH attack and the attack power significantly affects the stable pool populations.

scholarly journals Instability of cooperation in finite populations

2019 ◽  
Author(s):  
Chai Molina ◽  
David J. D. Earn
Keyword(s):  
Finite Population ◽  
Selection Process ◽  
Evolutionarily Stable Strategy ◽  
Evolutionary Game ◽  
Evolution Of Cooperation ◽  
Implicit Assumption ◽  
Stable Strategy ◽  
Infinite Population ◽  
Snowdrift Game ◽  
Evolutionarily Stable

AbstractEvolutionary game theory has been developed primarily under the implicit assumption of an infinite population. We rigorously analyze a standard model for the evolution of cooperation (the multi-player snowdrift game) and show that in many situations in which there is a cooperative evolutionarily stable strategy (ESS) if the population is infinite, there is no cooperative ESS if the population is finite (no matter how large). In these cases, contributing nothing is a globally convergently stable finite-population ESS, implying that apparent evolution of cooperation in such games is an artifact of the infinite population approximation. The key issue is that if the size of groups that play the game exceeds a critical proportion of the population then the infinite-population approximation predicts the wrong evolutionary outcome (in addition, the critical proportion itself depends on the population size). Our results are robust to the underlying selection process.

Pre-Rehearsal Questions of Performance Tradition and Play-Selection

2018 ◽  
Author(s):  
Kathleen Jeffs
Keyword(s):  
Golden Age ◽  
Selection Process ◽  
The United States ◽  
Spanish Golden Age ◽  
Royal Shakespeare Company ◽  
The Public ◽  
Performance Tradition ◽  
Performance Traditions ◽  
Public Consciousness

This chapter asks the questions: ‘what is the Spanish Golden Age and why should we stage its plays now?’ The Royal Shakespeare Company (RSC) Spanish season of 2004–5 came at a particularly ripe time for Golden Age plays to enter the public consciousness. This chapter introduces the Golden Age period and authors whose works were chosen for the season, and the performance traditions from the corrales of Spain to festivals in the United States. The chapter then treats the decision taken by the RSC to initiate a Golden Age season, delves into the play-selection process, and discusses the role of the literal translator in this first step towards a season. Then the chapter looks at ‘the ones that got away’, the plays that almost made the cut for production, and other worthy scripts from this period that deserve consideration for future productions.

Komunistki

2020 ◽  
pp. 671-692
Author(s):  
Aga Skrodzka
Keyword(s):  
Public Space ◽  
Visual Memory ◽  
Women's Movement ◽  
Women’S Rights ◽  
The Public ◽  
The Status ◽  
The Commons ◽  
Communist Past ◽  
Status Of Women

This article argues for the importance of preserving the visual memory of female communist agency in today’s Poland, at the time when the nation’s relationship to its communist past is being forcefully rearticulated with the help of the controversial Decommunization Act, which affects the public space of the commons. The wholesale criminalization of communism by the ruling conservative forces spurred a wave of historical and symbolic revisions that undermine the legacy of the communist women’s movement, contributing to the continued erosion of women’s rights in Poland. By looking at recent cinema and its treatment of female communists as well as the newly published accounts of the communist women’s movement provided by feminist historians and sociologists, the project sheds light on current cultural debates that address the status of women in postcommunist Poland and the role of leftist legacy in such debates.

scholarly journals A Study of Taxi Service Mode Choice Based on Evolutionary Game Theory

2019 ◽  
Vol 2019 ◽  
pp. 1-17
Author(s):  
Zhu Bai ◽  
Mingxia Huang ◽  
Shuai Bian ◽  
Huandong Wu
Keyword(s):  
Game Theory ◽  
Evolutionary Game Theory ◽  
Mode Choice ◽  
Evolutionary Game ◽  
Payoff Matrix ◽  
Game Model ◽  
Stable States ◽  
Taxi Service ◽  
Service Mode ◽  
The Impact

The emergence of online car-hailing service provides an innovative approach to vehicle booking but has negatively influenced the taxi industry in China. This paper modeled taxi service mode choice based on evolutionary game theory (EGT). The modes included the dispatching and online car-hailing modes. We constructed an EGT framework, including determining the strategies and the payoff matrix. We introduced different behaviors, including taxi company management, driver operation, and passenger choice. This allowed us to model the impact of these behaviors on the evolving process of service mode choice. The results show that adjustments in taxi company, driver, and passenger behaviors impact the evolutionary path and convergence speed of our evolutionary game model. However, it also reveals that, regardless of adjustments, the stable states in the game model remain unchanged. The conclusion provides a basis for studying taxi system operation and management.

Staking out an inshore commons: Pound-netting in Gilded Age America

2021 ◽  
Vol 33 (1) ◽  
pp. 3-15
Author(s):  
David Ress
Keyword(s):  
Nineteenth Century ◽  
Property Rights ◽  
Fish Species ◽  
Gilded Age ◽  
Late Nineteenth Century ◽  
Important Food ◽  
The Commons ◽  
Late Nineteenth ◽  
Over Exploitation ◽  
Specific Part

Controversy over the expansion of pound netting in the largest US fisheries of the late nineteenth century marked an early conflict between those who considered fisheries a commons and those who sought to establish property rights in a fishery. Pound-netters physically staked out a specific part of the sea for their exclusive use, and their conception of their property rights resulted in significant overfishing of important food – and oil – fish species. Here, just as with the commons that many economists argue inevitably result in over-exploitation of a resource, regulation was rebuffed and the fisheries collapsed.

scholarly journals Supervision of the Default Risk of Online Car-Hailing Platform from an Evolutionary Game Perspective

2021 ◽  
Vol 13 (2) ◽  
pp. 555
Author(s):  
Zhicheng Weng ◽  
Pinliang Luo
Keyword(s):  
Public Transportation ◽  
Default Risk ◽  
Control Mechanism ◽  
Evolutionary Game ◽  
Credit System ◽  
Credit Constraint ◽  
The Public ◽  
Supervision Mode ◽  
Public Transportation System ◽  
Internal Supervision

Online car-hailing services are becoming a key component of the public transportation system, despite there being some certain risks, especially default risk. Turning to the evolutionary game method, this research constructed an evolutionary game model of online car-hailing platform, and then analyzed the equilibrium state of three scenarios (i.e., no supervision, internal supervision of platform enterprises, and external supervision of regulators), followed by carrying out a simulation. The results showed that to realize the evolution stability strategies (ESS) of default risk control, a strong credit constraint or the establishment of a coordinated supervision mode with appropriate intensity are needed. On this basis, this research puts forward the coordinated “platform enterprise + regulator” supervision mode, as well as the following four specific strategies: Promoting the construction of a credit system, strengthening the construction of laws and regulations, establishing a service process control mechanism, and introducing innovative regulatory means.

scholarly journals Cooperation and competition between pair and multi-player social games in spatial populations

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Attila Szolnoki ◽  
Xiaojie Chen
Keyword(s):  
Public Goods ◽  
Evolutionary Game Theory ◽  
Evolutionary Game ◽  
Pair Interaction ◽  
Public Goods Game ◽  
Point Interactions ◽  
Social Games ◽  
The Public ◽  
Specific Parameter ◽  
Group Members

AbstractThe conflict between individual and collective interests is in the heart of every social dilemmas established by evolutionary game theory. We cannot avoid these conflicts but sometimes we may choose which interaction framework to use as a battlefield. For instance some people like to be part of a larger group while other persons prefer to interact in a more personalized, individual way. Both attitudes can be formulated via appropriately chosen traditional games. In particular, the prisoner’s dilemma game is based on pair interaction while the public goods game represents multi-point interactions of group members. To reveal the possible advantage of a certain attitude we extend these models by allowing players not simply to change their strategies but also let them to vary their attitudes for a higher individual income. We show that both attitudes could be the winner at a specific parameter value. Interestingly, however, the subtle interplay between different states may result in a counterintuitive evolutionary outcome where the increase of the multiplication factor of public goods game drives the population to a fully defector state. We point out that the accompanying pattern formation can only be understood via the multipoint or multi-player interactions of different microscopic states where the vicinity of a particular state may influence the relation of two other competitors.

scholarly journals Staphylococcus aureuscoagulases are exploitable yet stable public goods in clinically relevant conditions

2018 ◽  
Vol 115 (50) ◽  
pp. E11771-E11779 ◽  
Author(s):  
Urvish Trivedi ◽  
Jonas S. Madsen ◽  
Jake Everett ◽  
Cody Fell ◽  
Jakob Russel ◽  
...  
Keyword(s):  
Public Goods ◽  
Social Evolution ◽  
Defense Mechanism ◽  
Critical Role ◽  
Local Population ◽  
Coagulation Cascade ◽  
The Public ◽  
Innate Defense ◽  
The Commons

Coagulation is an innate defense mechanism intended to limit blood loss and trap invading pathogens during infection. However,Staphylococcus aureushas the ability to hijack the coagulation cascade and generate clots via secretion of coagulases. Although manyS. aureushave this characteristic, some do not. The population dynamics regarding this defining trait have yet to be explored. We report here that coagulases are public goods that confer protection against antimicrobials and immune factors within a local population or community, thus promoting growth and virulence. By utilizing variants of a methicillin-resistantS. aureuswe infer that the secretion of coagulases is a cooperative trait, which is subject to exploitation by invading mutants that do not produce the public goods themselves. However, overexploitation, “tragedy of the commons,” does not occur at clinically relevant conditions. Our micrographs indicate this is due to spatial segregation and population viscosity. These findings emphasize the critical role of coagulases in a social evolution context and provide a possible explanation as to why the secretion of these public goods is maintained in mixedS. aureuscommunities.

Management of Publicly Owned Forests

1988 ◽  
Vol 64 (3) ◽  
pp. 193-198 ◽  
Author(s):  
G. Baskerville
Keyword(s):  
Productive Capacity ◽  
The Public ◽  
Management Actions ◽  
Proper Form ◽  
The People ◽  
Resource Dynamics ◽  
Industrial Use ◽  
Publicly Owned ◽  
Over Exploitation ◽  
Public Forests

For two reasons, planning and implementing management for publicly-owned forests is conducted in an environment that almost guarantees failure. First, group ownership is associated with a strong tendency towards over-exploitation (the tragedy of the commons), and second public ownership entails a heavy administrative overhead.The public allows industry to use publicly-owned forests and spends the revenue from exploitation on roads, schools health care, unemployment insurance and so on. The public owners are unwilling to limit industrial use of the forest to keep it in balance with the productive capacity of the forests because this would limit the benefits they receive and because they do not as individuals experience the shared cost of exploitation. Meanwhile, the people who own 90% of Canada's forests have until recently seen fit to spend only 5% of the taxes derived from their industrial use for maintaining their productive capacity. In effect the people of Canada are slum landlords. Like slum landlords, they have not returned to their properties enough money for their basic maintenance. The biggest problem in managing our public forests is in overcoming the owners' resistance to spending enough of the money generated by the forests to manage them in a technically adequate way over long period of time.The second major problem is the tendency of the agencies managing publicly-owned forests to shift from managing the forest to managing its use. This arises partly from the way in which the owners (the public) participate in the management process and partly because public money is used for management.The public owns the resource and must set goals. Unfortunately because they are so remote from the property and their understanding of resource dynamics is so trivial, the public tend to state vague goals accompanied by specific management actions with little thought to the cause/effect connections between them. Technically designed management tends to be over-ridden by socially comfortable solutions that do not solve the real management problems existing in the woods.Use of public funds necessitates creating a paper trail satisfactory to auditors. Consequently professionals responsible for managing the public forests find themselves spending more and more time ensuring that the administrative reporting of actions taken is up to date and in the proper form, and less and less time ensuring that the actions taken are the technically right ones to achieve the stated goals in the forest.

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