Letteratura scientifica selezionata sul tema "Constant payoff"
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Articoli di riviste sul tema "Constant payoff"
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Sautmann, Anja. "Age-Dependent Payoffs and Assortative Matching by Age in a Market with Search". American Economic Journal: Microeconomics 9, n. 2 (1 maggio 2017): 263–94. http://dx.doi.org/10.1257/mic.20150237.
Testo completoAbstract (sommario):
This paper considers a matching market with two-sided search and transferable utility where match payoffs depend on age at marriage (time until match) and search is finite. We define and prove existence of equilibrium, and provide sufficient conditions for positive assortative matching that build on restricting the slope and curvature of the marriage payoff function to generate single-peaked preferences in age and therefore convex matching sets. Payoff functions that are incompatible with positive sorting by age include all strictly increasing functions and constant flow payoffs enjoyed for some finite period. (JEL C78, D83, J12)
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Kufel, Tadeusz, Sławomir Plaskacz e Joanna Zwierzchowska. "Strong and Safe Nash Equilibrium in Some Repeated 3-Player Games". Przegląd Statystyczny 65, n. 3 (30 gennaio 2019): 271–95. http://dx.doi.org/10.5604/01.3001.0014.0540.
Testo completoAbstract (sommario):
The paper examines an infinitely repeated 3-player extension of the Prisoner’s Dilemma game. We consider a 3-player game in the normal form with incomplete information, in which each player has two actions. We assume that the game is symmetric and repeated infinitely many times. At each stage, players make their choices knowing only the average payoffs from previous stages of all the players. A strategy of a player in the repeated game is a function defined on the convex hull of the set of payoffs. Our aim is to construct a strong Nash equilibrium in the repeated game, i.e. a strategy profile being resistant to deviations by coalitions. Constructed equilibrium strategies are safe, i.e. the non-deviating player payoff is not smaller than the equilibrium payoff in the stage game, and deviating players’ payoffs do not exceed the nondeviating player payoff more than by a positive constant which can be arbitrary small and chosen by the non-deviating player. Our construction is inspired by Smale’s good strategies described in Smale’s paper (1980), where the repeated Prisoner’s Dilemma was considered. In proofs we use arguments based on approachability and strong approachability type results.
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Nagel, Stefan, e Amiyatosh Purnanandam. "Banks’ Risk Dynamics and Distance to Default". Review of Financial Studies 33, n. 6 (17 ottobre 2019): 2421–67. http://dx.doi.org/10.1093/rfs/hhz125.
Testo completoAbstract (sommario):
Abstract We adapt structural models of default risk to take into account the special nature of bank assets. The usual assumption of lognormally distributed asset values is not appropriate for banks. Typical bank assets are risky debt claims with concave payoffs. Because of the payoff nonlinearity, bank asset volatility rises following negative shocks to borrower asset values. As a result, standard structural models with constant asset volatility can severely understate banks’ default risk in good times when asset values are high. Additionally, bank equity return volatility is much more sensitive to negative shocks to asset values than in standard structural models.
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Maestri, Lucas. "Bonus Payments versus Efficiency Wages in the Repeated Principal-Agent Model with Subjective Evaluations". American Economic Journal: Microeconomics 4, n. 3 (1 agosto 2012): 34–56. http://dx.doi.org/10.1257/mic.4.3.34.
Testo completoAbstract (sommario):
We study an infinitely repeated principal-agent model with subjective evaluations. We compare the surplus in efficiency-wage equilibria and in bonus-payments equilibria. The agent receives a constant wage and is motivated by the threat of dismissal in efficiency-wage equilibria. The agent receives a bonus and quits the relationship after disagreements between his self-evaluation and the principal's performance appraisal in bonus-payments equilibria. We construct a class of equilibria with bonus payments that approach efficiency as patience increases. In contrast, payoffs from efficiency-wage equilibria are bounded away from the Pareto-payoff frontier for any discount factor. (JEL D82, J33, J41)
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KÖHLER, WOLFGANG R. "UNIQUE EQUILIBRIA IN THE RUBINSTEIN BARGAINING MODEL WHEN THE PAYOFF SET IS NON-CONVEX". International Game Theory Review 08, n. 03 (settembre 2006): 469–82. http://dx.doi.org/10.1142/s0219198906001028.
Testo completoAbstract (sommario):
I give necessary and sufficient conditions on the payoff set that guarantee uniqueness of the equilibrium in the Rubinstein bargaining model. The conditions encompass a class of non-convex or disconnected payoff sets with discontinuous Pareto frontiers. Roughly speaking, the equilibrium is unique if the objective function of the corresponding Nash-bargaining game has a unique maximum. I extend the analysis to games where the time between offers is not constant.
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Lutsenko, Mikhail M. "Generalized Integral Equations for Timing Games". Contributions to Game Theory and Management 16 (2023): 182–91. http://dx.doi.org/10.21638/11701/spbu31.2023.11.
Testo completoAbstract (sommario):
We consider timing games, the payoff functions of which have additional break lines outside the unit square diagonal. A special case of such games are games with piecewise constant payoff functions. Solving these games is reduced to solving a pair of integral equations for the distribution functions of equalizing strategies. The proposed solution methods can be used in the study of random walks on a segment in a variable environment.
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Braithwaite, R. Scott. "Can Life Expectancy and QALYs Be Improved by a Framework for Deciding Whether to Apply Clinical Guidelines to Patients With Severe Comorbid Disease?" Medical Decision Making 31, n. 4 (10 febbraio 2011): 582–95. http://dx.doi.org/10.1177/0272989x10386117.
Testo completoAbstract (sommario):
Background: Guidelines with short-term harms and long-term benefits are often applied to chronically ill patients who may not benefit. The payoff time framework has been proposed (i.e., do not apply a guideline if a patient’s life expectancy (LE) is shorter than when a guideline’s cumulative incremental benefits first exceed its cumulative incremental harms), but its health impact is unclear. Objective: To investigate whether the payoff time framework improves LE and/or quality-adjusted life-years (QALY) for chronically ill patients. Methods: I evaluate impact of the payoff time framework on LE and QALYs, assuming (1) high and constant background mortality rate from chronic illness (≥ 10% per year), (2) immediate guideline-related harm with probability < 1, and (3) constant guideline-related benefit that occurs over an extended time. I apply the framework to questions of whether to screen chronically ill 50-year-old women for colorectal cancer using colonoscopy, and whether to advocate intensive glucose control for chronically ill diabetics. Results: If a guideline’s payoff time is greater than a patient’s LE, then withholding that guideline will increase LE and QALYs for that patient. For a 50-year-old chronically ill woman with background mortality > 0.15 per year (corresponding to LE < 6.5 years), withholding CR screening will increase LE. For a diabetic with background mortality > 0.11 per year (corresponding to LE < 9.4 years), withholding CR screening will increase QALYs. Conclusion: The payoff time framework may indicate when withholding a guideline with short-term harms and long-term benefits may increase LE and/or QALY.
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CHATTERJEE, KRISHNENDU, e RUPAK MAJUMDAR. "DISCOUNTING AND AVERAGING IN GAMES ACROSS TIME SCALES". International Journal of Foundations of Computer Science 23, n. 03 (aprile 2012): 609–25. http://dx.doi.org/10.1142/s0129054112400308.
Testo completoAbstract (sommario):
We introduce two-level discounted and mean-payoff games played by two players on a perfect-information stochastic game graph. The upper level game is a discounted or mean-payoff game and the lower level game is a (undiscounted) reachability game. Two-level games model hierarchical and sequential decision making under uncertainty across different time scales. For both discounted and mean-payoff two-level games, we show the existence of pure memoryless optimal strategies for both players and an ordered field property. We show that if there is only one player (Markov decision processes), then the values can be computed in polynomial time. It follows that whether the value of a player is equal to a given rational constant in two-level discounted or mean-payoff games can be decided in NP ∩ coNP . We also give an alternate strategy improvement algorithm to compute the value.
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Szilagyi, Miklos N., e Iren Somogyi. "Agent-Based Simulation of N-Person Games with Crossing Payoff Functions". Complex Systems 17, n. 4 (15 dicembre 2008): 427–39. http://dx.doi.org/10.25088/complexsystems.17.4.427.
Testo completoAbstract (sommario):
We report on computer simulation experiments using our agent-based simulation tool to model uniform N-person games with crossing payoff functions. We study the case when agents are greedy simpletons who imitate the action of their neighbor that received the highest payoff for its previous action. The individual agents may cooperate with each other for the collective interest or may defect, that is, pursue their selfish interests only. After a certain number of iterations the proportion of cooperators stabilizes to either a constant value or oscillates around such a value. The payoff (reward/penalty) functions are given as two straight lines: one for the cooperators and another for the defectors. The payoff curves are functions of the ratio of cooperators to the total number of agents. Even if the payoff functions are linear, four free parameters determine them. In this investigation only crossing payoff functions are considered. We have investigated the behavior of the agents systematically. The results show that the solutions are nontrivial and in some cases quite irregular. They show drastic changes for the Leader Game in the narrow parameter range of 1.72 ≤ P ≤ 1.75. This behavior is similar to that observed in [1] for the N-Person Chicken Game. Irregular solutions were also found for the Reversed Stag Hunt Game.
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Selten, Reinhard, e Thorsten Chmura. "Stationary Concepts for Experimental 2x2-Games". American Economic Review 98, n. 3 (1 maggio 2008): 938–66. http://dx.doi.org/10.1257/aer.98.3.938.
Testo completoAbstract (sommario):
Five stationary concepts for completely mixed 2x2-games are experimentally compared: Nash equilibrium, quantal response equilibrium, action-sampling equilibrium, payoff-sampling equilibrium (Martin J. Osborne and Ariel Rubinstein 1998), and impulse balance equilibrium. Experiments on 12 games, 6 constant sum games, and 6 nonconstant sum games were run with 12 independent subject groups for each constant sum game and 6 independent subject groups for each nonconstant sum game. Each independent subject group consisted of four players 1 and four players 2, interacting anonymously over 200 periods with random matching. The comparison of the five theories shows that the order of performance from best to worst is as follows: impulse balance equilibrium, payoff-sampling equilibrium, action-sampling equilibrium, quantal response equilibrium, Nash equilibrium. (JEL C70, C91)
Tesi sul tema "Constant payoff"
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Ragel, Thomas. "Approchabilité et paiement constant dans les jeux stochastiques". Electronic Thesis or Diss., Université Paris sciences et lettres, 2024. http://www.theses.fr/2024UPSLD017.
Testo completoAbstract (sommario):
Cette thèse explore deux sujets distincts de la théorie des jeux.Premièrement, elle examine la propriété du paiement constant dans le contexte des jeux stochastiques finis à somme nulle, un sujet précédemment étudié dans le cadre des jeux absorbants et des jeux stochastiques à paiement escompté. Cette thèse se concentre sur le cas de l'horizon fini et valide une conjecture énoncée par Sorin, Venel et Vigeral : elle démontre que lorsque la durée du jeu est suffisamment longue, il existe une paire de stratégies approximativement optimales telles que le paiement moyen attendu à tout instant du jeu est proche de la valeur.Deuxièmement, cette thèse examine l'approchabilité des ensembles convexes dans les jeux absorbants avec des paiements vectoriels. Plus précisément, nous montrons qu'une condition nécessaire et une autre condition suffisante pour l'approchabilité faible d'un ensemble convexe, établies par Flesch, Laraki et Perchet, restent valides dans le cas général. Pour ce faire, nous étendons les résultats sur l'approchabilité de Blackwell à une configuration dans laquelle les poids de l'étape dépendent des actions passées ainsi que de l'action actuelle du joueur 1 (le joueur s'approchant). De plus, nous prouvons que la stratégie utilisée pour approcher l'ensemble convexe peut être définie en blocs de longueur fixe, ce qui lui confère une mémoire bornée et peut être mise en œuvre par un automate finiThis thesis explores two distinct topics within game theory.Firstly, it investigates the constant payoff property in the context of zero-sum finite stochastic games, a topic previously explored in the context of absorbing games and discounted stochastic games. This thesis focuses on the finite-horizon case and validates a conjecture stated by Sorin, Venel and Vigeral: it proves that when the duration of the game is large enough, there exists a pair of approximately optimal strategies such that the expected average payoff at any instant of the game is close to the value.Secondly, this thesis examines the approachability of convex sets in absorbing games with vector payoffs. Specifically, we show that a necessary condition and a different sufficient condition for weak approachability of a convex set, established by Flesch, Laraki, and Perchet, remain valid in the general case. To do so, we extend results on Blackwell approachability to a setup in which stage weights depend on past actions as well as the current action of Player 1 (the approaching player). Additionally, we prove that the strategy used to approach the convex set can be defined in blocks of fixed length, and so it has bounded memory and can be implemented by a finite automata
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Ismail, Munira. "Essays on the Impact of Institutional Investors on Firms' Liquidity and Payout Policy". ScholarWorks@UNO, 2015. http://scholarworks.uno.edu/td/1994.
Testo completoAbstract (sommario):
This dissertation consists of 2 essays in the area of corporate finance. The title of my first essay is “Impact of Institutional Investors on Firms’ Financial Constraint and Liquidity”. We can find ample evidences in existing literature which show that institutional investors play a vital role in the corporate world. Many researchers have linked institutional investors to activism, monitoring benefits, mitigating the cost of debt using government bond, spin off activities and improving information asymmetry problem. In the first essay, I would like to add another dimension to institutional investors’ literature by examining institutional investors’ role in mitigating financial constraint problem in the firm. Institutional investors have large financial networks and make large financial investment in firms. Their presence might help firms attract external capital. I am using 2 financial constraint measurements; KZ index (Lamont, Polk, Saa-Requejo, 2001) and bank line of credit (Sufi, 2009). I am also adding additional measurement for financial constraint using notes payable. I find evidences to support the hypotheses that institutional investors’ presence and ownership mitigate financial constraints. The title of my second essay is “Long- and Short-Term Institutional Investors and Payout Policy”. In the second essay, I examine the relationship between the firms’ payout policy and the presence/ownership of certain type of institutional investors. I classify the types of institutional investors using Bushee’s (1998, 2001) classification of institutional investors. I find that the presence and the magnitude of long term institutional investors positively affect the likelihood and the magnitude of dividend. I also find that the presence and the magnitude of short term institutional investors positively affect the likelihood and the magnitude of share repurchases. This study suggests that the presence of different types of institutional investors can affect certain type of payout policy.
Keywords: Transient; dedicated; monitoring; trading
Libri sul tema "Constant payoff"
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Back, Kerry E. Continuous-Time Markets. Oxford University Press, 2017. http://dx.doi.org/10.1093/acprof:oso/9780190241148.003.0013.
Testo completoAbstract (sommario):
A continuous‐time model of a securities market is introduced. The intertemporal budget constraint is defined. SDF processes and prices of risks are defined and characterized. Many properties of SDF process are analogous to those in a single‐period model, including the relation to the risk‐free rate, orthogonal projections, the Hansen‐Jagannathan bound, and factor pricing. To value future cash flows using an SDF process, we need to assume a local martingale is a martingale. Sufficient conditions including Novikov’s condition are discussed. Use of the martingale representation theorem in a complete market to derive a portfolio that replicates a payoff is explained. A Markovian model is introduced, in which the investment opportunity set depends on state variables that form a Markov process.
Capitoli di libri sul tema "Constant payoff"
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Young, H. Peyton, Heinrich H. Nax, Maxwell N. Burton-Chellew e Stuart A. West. "Learning in a Black Box". In Spontaneous Order, 190–218. Oxford University PressOxford, 2024. http://dx.doi.org/10.1093/oso/9780198892908.003.0013.
Testo completoAbstract (sommario):
Abstract This chapter studies strategic behavior when agents have no information about the structure of the underlying game and they cannot observe other agents’ actions or payoffs. Even when players have no such information, there are simple payoff-based learning rules that lead to Nash equilibrium in many types of games, as shown in Chapter 8. A key feature of these trial-and-error rules is that subjects search differently depending on whether their payoffs increase, stay constant, or decrease. This chapter analyzes learning behavior in a laboratory setting and finds strong empirical confirmation for these asymmetric search behaviors in the context of voluntary contribution games. By varying the amount of information, we show that these behaviors are also present even when subjects have full information about the game.
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Young, H. Peyton, Itai Arieli, Yakov Babichenko e Ron Peretz. "The Speed of Innovation Diffusion in Social Networks". In Spontaneous Order, 342–74. Oxford University PressOxford, 2024. http://dx.doi.org/10.1093/oso/9780198892908.003.0020.
Testo completoAbstract (sommario):
Abstract New ways of doing things often get started through the actions of a few innovators, then diffuse rapidly as more and more people come into contact with prior adopters in their social network. Much of the literature focuses on the speed of diffusion as a function of the network topology. In practice, the topology may not be known with any precision, and it is constantly in flux as links are formed and severed. This chapter establishes an upper bound on the expected waiting time until a given proportion of the population has adopted that holds independently of the network structure. The bound holds for directed and undirected networks of arbitrary size and degree distribution, and for multiple competing innovations with different payoffs.
Atti di convegni sul tema "Constant payoff"
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Wesson, Elizabeth N., e Richard H. Rand. "Alternate Models of Replicator Dynamics". In ASME 2013 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/detc2013-12046.
Testo completoAbstract (sommario):
Models of evolutionary dynamics are often approached via the replicator equation, which in its standard form is given by x.i=xifix-ϕ,i = 1,…, n, where xi is the frequency, or relative abundance, of strategy i, fi is its fitness, and ϕ=∑i=1nxifi is the average fitness. A game-theoretic aspect is introduced to the model via the payoff matrix A, where Ai,j is the expected payoff of i vs. j, by taking fi(x) = (A·x)i. This model is based on the exponential model of population growth, ẋi = xifi, with ϕ introduced in order both to hold the total population constant and to model competition between strategies. We analyze the dynamics of analogous models for the replicator equation of the form x.i=gxifi-ϕ, for selected growth functions g.
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Shi, Zheyuan Ryan, Ziye Tang, Long Tran-Thanh, Rohit Singh e Fei Fang. "Designing the Game to Play: Optimizing Payoff Structure in Security Games". In Twenty-Seventh International Joint Conference on Artificial Intelligence {IJCAI-18}. California: International Joint Conferences on Artificial Intelligence Organization, 2018. http://dx.doi.org/10.24963/ijcai.2018/71.
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We study Stackelberg Security Games where the defender, in addition to allocating defensive resources to protect targets from the attacker, can strategically manipulate the attacker’s payoff under budget constraints in weighted L^p-norm form regarding the amount of change. For the case of weighted L^1-norm constraint, we present (i) a mixed integer linear program-based algorithm with approximation guarantee; (ii) a branch-and-bound based algorithm with improved efficiency achieved by effective pruning; (iii) a polynomial time approximation scheme for a special but practical class of problems. In addition, we show that problems under budget constraints in L^0 and weighted L^\infty-norm form can be solved in polynomial time.
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Tran, Anh, Elena Asparouhova, Peter Bossaerts e Dan Lu. "The Role of Financial Markets in Mitigating Credit Market Bubbles". In 5th World Conference on Business, Management, Finance, Economics, and Marketing, 63. Eurasia Conferences, 2024. http://dx.doi.org/10.62422/978-81-968539-6-9-041.
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We investigate how long an insolvent debtor can avoid default when survival is beneficial to creditors collectively, but individual creditors gain by forcing early repayment. Theory predicts that the debt is not rolled over and default is immediate. With 23 experimental sessions, default is never immediate, with or without secondary debt markets. With markets, prices do not reveal survival length but correlate with payoffs. Creditors are better off with markets, but markets exacerbate wealth inequality. Survival length is reduced upon repetition with the same cohort. When new creditors are introduced, survival length remains constant, even with access to default history.
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Avşar, Alkim Z., Jordan L. Stern e Paul T. Grogan. "Measuring Risk Attitudes for Strategic Decision-Making in a Collaborative Engineering Design Process". In ASME 2022 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/detc2022-90216.
Testo completoAbstract (sommario):
Abstract This paper evaluates a questionnaire-based risk attitude assessment method to quantify individual risk attitudes for strategic, multi-actor design decisions. A lottery-equivalence questionnaire elicits a utility curve for risky payoffs which is fit to a Constant Absolute Risk Aversion (CARA) model. Secondary data from a multi-actor design experiment provides observations of strategic decisions in two-actor design games for validation. 124 participants complete the risk attitude questionnaire and a series of 29 experimental tasks. Assuming participants follow the risk dominance equilibrium selection criterion, a risk-neutral utility function accurately predicts 62.2% of decisions. Incorporating risk attitudes elicited from the questionnaire only increases the accuracy to 63.3% while incorporating risk attitudes inferred from observations increases the accuracy to 77.5%. While participants exhibit differential risk attitudes in design tasks, results show the lottery-equivalent questionnaire does not provide risk attitudes consistent with strategic design decisions. Results support findings that risk in the engineering domain is contextual. This paper concludes that risk attitude is an important factor in understanding strategic decisions in interactive engineering design settings and understanding risk attitudes can help create more efficient design processes.
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Liu, Zeyang, Lipeng Wan, Xue Sui, Zhuoran Chen, Kewu Sun e Xuguang Lan. "Deep Hierarchical Communication Graph in Multi-Agent Reinforcement Learning". In Thirty-Second International Joint Conference on Artificial Intelligence {IJCAI-23}. California: International Joint Conferences on Artificial Intelligence Organization, 2023. http://dx.doi.org/10.24963/ijcai.2023/24.
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Sharing intentions is crucial for efficient cooperation in communication-enabled multi-agent reinforcement learning. Recent work applies static or undirected graphs to determine the order of interaction. However, the static graph is not general for complex cooperative tasks, and the parallel message-passing update in the undirected graph with cycles cannot guarantee convergence. To solve this problem, we propose Deep Hierarchical Communication Graph (DHCG) to learn the dependency relationships between agents based on their messages. The relationships are formulated as directed acyclic graphs (DAGs), where the selection of the proper topology is viewed as an action and trained in an end-to-end fashion. To eliminate the cycles in the graph, we apply an acyclicity constraint as intrinsic rewards and then project the graph in the admissible solution set of DAGs. As a result, DHCG removes redundant communication edges for cost improvement and guarantees convergence. To show the effectiveness of the learned graphs, we propose policy-based and value-based DHCG. Policy-based DHCG factorizes the joint policy in an auto-regressive manner, and value-based DHCG factorizes the joint value function to individual value functions and pairwise payoff functions. Empirical results show that our method improves performance across various cooperative multi-agent tasks, including Predator-Prey, Multi-Agent Coordination Challenge, and StarCraft Multi-Agent Challenge.
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Żychowski, Adam, Jacek Mańdziuk, Elizabeth Bondi, Aravind Venugopal, Milind Tambe e Balaraman Ravindran. "Evolutionary Approach to Security Games with Signaling". In Thirty-First International Joint Conference on Artificial Intelligence {IJCAI-22}. California: International Joint Conferences on Artificial Intelligence Organization, 2022. http://dx.doi.org/10.24963/ijcai.2022/88.
Testo completoAbstract (sommario):
Green Security Games have become a popular way to model scenarios involving the protection of natural resources, such as wildlife. Sensors (e.g. drones equipped with cameras) have also begun to play a role in these scenarios by providing real-time information. Incorporating both human and sensor defender resources strategically is the subject of recent work on Security Games with Signaling (SGS). However, current methods to solve SGS do not scale well in terms of time or memory. We therefore propose a novel approach to SGS, which, for the first time in this domain, employs an Evolutionary Computation paradigm: EASGS. EASGS effectively searches the huge SGS solution space via suitable solution encoding in a chromosome and a specially-designed set of operators. The operators include three types of mutations, each focusing on a particular aspect of the SGS solution, optimized crossover and a local coverage improvement scheme (a memetic aspect of EASGS). We also introduce a new set of benchmark games, based on dense or locally-dense graphs that reflect real-world SGS settings. In the majority of 342 test game instances, EASGS outperforms state-of-the-art methods, including a reinforcement learning method, in terms of time scalability, nearly constant memory utilization, and quality of the returned defender's strategies (expected payoffs).
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Fonseca, S. Hassig, C. Bridge, Z. Liu, W. Brouwer, N. Vodnikov e P. Spesivtsev. "New Coiled Tubing Fatigue Management System with Real-Time Vessel Data: Step-Change to Cost and Reliability in Open-Water Interventions". In SPE/ICoTA Well Intervention Conference and Exhibition. SPE, 2024. http://dx.doi.org/10.2118/218297-ms.
Testo completoAbstract (sommario):
Abstract Early attempts to monitor coiled tubing (CT) fatigue in open-water interventions relied on basic statistical methods with a constant damage rate and broad generalizations of sea conditions. The new CT fatigue management system (FMS) comprises hardware and software that improve fatigue tracking. It tracks high-cycle fatigue (HCF) and low-cycle fatigue (LCF) simultaneously and in real time, elevating the accuracy, immediacy, and reliability of CT fatigue monitoring in open-water interventions. The hardware monitors vessel pitch and roll in real time and relays the data to an acquisition system where they are combined with CT depth and circulating pressure. The new acquisition software consumes these data as well as a CT string fatigue life database and geometry and positions of the CT string, work drum, and payout sheave. LCF and HCF are accurately modeled, and the string fatigue life is updated in real time. That information allows the operation to strategically cycle the CT pipe to manage fatigue more efficiently and extend the time before a trim is necessary. The traditional statistical method recorded a cumulative CT fatigue damage of 16% over a 14-hour job. In that same timeframe, the CT FMS measured a cumulative fatigue of 3.8%. Since the CT FMS updates damage rate continuously in response to vessel dynamics and uses a nonlinear methodology to combine HCF and LCF, it reduces inaccuracy and eliminates unnecessary safety factors associated with the statistical method. By improving precision and reliability, the real-time CT FMS safely extended the useful life of CT pipes by 75%. The CT FMS also improves operational integrity by introducing alarm threshold settings and custom material parameters. Alarms are raised reflecting fatigue life growth, tubing payout, and changes to sea conditions. This provides the operator with real-time, actionable data to ensure a more even distribution of the fatigue along the CT. Besides extending useful life, this reduces the risk of CT failure, which can lead to costly downtime, reputational damage, and production losses. The string's operating limits are more accurately monitored, which extends the capacity of the CT into harsher environments, longer operations, and riserless interventions of wider workscope. The CT FMS automates workflows that previously required a dedicated technician, reducing crew size on board. The introduction of CT in open-water interventions brought with it the risk of CT failure, which is inherent to any operation that handles CT pipe. This industry first, real-time CT FMS combines HCF and LCF monitoring and is a step change from the traditional methods to address these CT-related risks. Furthermore, the CT FMS elevates overall operational integrity, increases operational efficiency, and extends the operational envelope and application of CT in open-water interventions.
Rapporti di organizzazioni sul tema "Constant payoff"
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Atuesta, Laura, e Juan Manuel Puerta. IDB-9: Competitive Regional and Global International Integration. Inter-American Development Bank, marzo 2013. http://dx.doi.org/10.18235/0010513.
Testo completoAbstract (sommario):
Trade and regional integration in Latin America and the Caribbean (LAC) have been constant goals of the Inter-American Development Bank (IDB, or Bank) since its inception. While the Bank has historically had a very active role in policy discussions with and technical assistance to countries on these issues, it has not had a substantial regional lending program in this area. Indeed, the trade and integration portfolio is divided between the nonlending part, mostly led by the Trade and Integration Sector, and the infrastructure integration part (where the bulk of the lending is concentrated), led by the infrastructure sector. However, this lending portfolio is composed almost exclusively of national projects with typically no proven regional benefits beyond the purely national ones. The main reason for the paucity of projects with regional benefits is that working regionally is associated with higher transaction costs for both the Bank and the countries, and the Bank still lacks a concessional lending instrument. Under the IDB-9 Agreement, the Bank reiterated regional integration as one of the priorities, attaching a specific lending target to it. Management was required to produce a new regional integration strategy and an action plan to guide the actions of the Bank. The new Integration Strategy has a thorough understanding of the nature of the challenges to regional integration and contains a complete and sound diagnosis of trade issues in LAC. Although the diagnosis of infrastructure integration and regional public goods is weaker, the Strategy remains relevant to identify the main challenges and the recent evolution of trade and integration in LAC. The Strategy and Action Plan provide little guidance, however, beyond outlining the main ideas. Although a first draft identified the need for concessional instruments, the final version proposed only a "smart mix" of existing instruments. The Strategy does not clearly define and build on the Bank¿s comparative advantage or record of past experience. The definition and classification of "regional integration projects" are confused; depending on the source chosen, regional integration projects represent between 0.6% and 25% of Bank lending in 2011. The baseline for lending in the IDB-9 Agreement (10%) is unrealistic given the Bank's historic performance, and projects without any connection with either regional integration or the Integration Strategy are being labeled as regional. The Strategy and the Action Plan mostly describe what the Bank currently does rather than provide strategic leadership or direction. The Bank is now at a crossroads. Different options are available depending on the risk appetite of Governors and the willingness of the LAC Region to advance toward regional integration. Instead of pursuing the current low-risk and low-payoff strategy, Governors may wish to tackle the problems that have precluded lending for regional integration, including providing preferential access to resources for regional integration projects with clear eligibility guidelines. In any case Management should revisit its classification system for regional lending and provide a more transparent and more accurate picture of actual Bank work in this area.