On axiomatizations of the Shapley value for assignment games

We consider the problem of axiomatizing the Shapley value on the class of assignment games. We first show that several axiomatizations of the Shapley value on the class of all TU-games do not characterize this solution on the class of assignment games by providing alternative solutions that satisfy these axioms. However, when considering an assignment game as a communication graph game where the game is simply the assignment game and the graph is a corresponding bipartite graph buyers are connected with sellers only, we show that Myerson's component efficiency and fairness axioms do characterize the Shapley value on the class of assignment games. Moreover, these two axioms have a natural interpretation for assignment games. Component efficiency yields submarket efficiency stating that the sum of the payoffs of all players in a submarket equals the worth of that submarket, where a submarket is a set of buyers and sellers such that all buyers in this set have zero valuation for the goods offered by the sellers outside the set, and all buyers outside the set have zero valuations for the goods offered by sellers inside the set. Fairness of the graph game solution boils down to valuation fairness stating that only changing the valuation of one particular buyer for the good offered by a particular seller changes the payoffs of this buyer and seller by the same amount.

Sztochasztikus csődjátékok - avagy hogyan osszunk szét egy bizonytalan méretű tortát? = Stochastic bankruptcy games. How can a cake of uncertain dimensions be divided?

A kooperatív játékelmélet egyik legjelentősebb eredménye, hogy számos konfliktushelyzetben stabil megoldást nyújt. Ez azonban csak statikus és determinisztikus környezetben alkalmazható jól. Most megmutatjuk a mag egy olyan kiterjesztését - a gyenge szekvenciális magot -, amely képes valós, dinamikus, bizonytalan környezetben is eligazítást nyújtani. A megoldást a csődjátékok példájára alkalmazzuk, és segítségével megvizsgáljuk, hogy a pénzügyi irodalom ismert elosztási szabályai közül melyek vezetnek stabil, fenntartható eredményre. _______ One of the most important achievements of cooperative game theory is to provide a stable solution to numerous conflicts. The solutions it presents, on the other hand, have been limited to situations in a static, deterministic environment. The paper examines how the core can be extended to a more realistic, dynamic and uncertain scenario. The bankruptcy games studied are ones where the value of the estate and of the claims are stochastic, and a Weak Sequential Core is used as the solution concept for them. The author tests the stability of a number of well known division rules in this stochastic setting and finds that most are unstable, except for the Constrained Equal Awards rule, which is the only one belonging to the Weak Sequential Core.

Stable sets in one-seller assignment games

We consider von Neumann -- Morgenstern stable sets in assignment games with one seller and many buyers. We prove that a set of imputations is a stable set if and only if it is the graph of a certain type of continuous and monotone function. This characterization enables us to interpret the standards of behavior encompassed by the various stable sets as possible outcomes of well-known auction procedures when groups of buyers may form bidder rings. We also show that the union of all stable sets can be described as the union of convex polytopes all of whose vertices are marginal contribution payoff vectors. Consequently, each stable set is contained in the Weber set. The Shapley value, however, typically falls outside the union of all stable sets.

The kernel is in the least core for permutation games

Permutation games are totally balanced transferable utility cooperative games arising from certain sequencing and re-assignment optimization problems. It is known that for permutation games the bargaining set and the core coincide, consequently, the kernel is a subset of the core. We prove that for permutation games the kernel is contained in the least core, even if the latter is a lower dimensional subset of the core. By means of a 5-player permutation game we demonstrate that, in sense of the lexicographic center procedure leading to the nucleolus, this inclusion result can not be strengthened. Our 5-player permutation game is also an example (of minimum size) for a game with a non-convex kernel.

Lexicographic allocations and extreme core payoffs: the case of assignment games

We consider various lexicographic allocation procedures for coalitional games with transferable utility where the payoffs are computed in an externally given order of the players. The common feature of the methods is that if the allocation is in the core, it is an extreme point of the core. We first investigate the general relationship between these allocations and obtain two hierarchies on the class of balanced games. Secondly, we focus on assignment games and sharpen some of these general relationship. Our main result is the coincidence of the sets of lemarals (vectors of lexicographic maxima over the set of dual coalitionally rational payoff vectors), lemacols (vectors of lexicographic maxima over the core) and extreme core points. As byproducts, we show that, similarly to the core and the coalitionally rational payoff set, also the dual coalitionally rational payoff set of an assignment game is determined by the individual and mixed-pair coalitions, and present an efficient and elementary way to compute these basic dual coalitional values. This provides a way to compute the Alexia value (the average of all lemacols) with no need to obtain the whole coalitional function of the dual assignment game.

Assignment Games with Externalities

We examine assignment games, wherematched pairs of firms and workers create some monetary value to distribute among themselves and the agents aim to maximize their payoff. In the majority of this literature, externalities - in the sense that a pair’s value depends on the pairing of the others - have been neglected. However, inmost applications a firm’s success depends on, say, the success of its rivals and suppliers. Thus, it is natural to ask how the classical results on assignment games are affected by the introduction of externalities? The answer is – dramatically. We find that (i) a problem may have no stable outcome, (ii) stable outcomes can be inefficient (not maximize total value), (iii) efficient outcomes can be unstable, and (iv) the set of stable outcomes may not form a lattice. We show that stable outcomes always exist if agents are "pessimistic." This is a knife-edge result: there are problems in which the slightest optimism by a single pair erases all stable outcomes.

The prisoners' dilemma, congestion games and correlation

Social dilemmas, in particular the prisoners' dilemma, are represented as congestion games, and within this framework soft correlated equilibria as introduced by Forgó F. (2010, A generalization of correlated equilibrium: A new protocol. Mathematical Social Sciences 60:186-190) is used to improve inferior Nash payoffs that are characteristic of social dilemmas. These games can be extended to several players in different ways preserving some important characteristics of the original 2-person game. In one of the most frequently studied models of the n-person prisoners' dilemma game we measure the performance of the soft correlated equilibrium by the mediation and enforcement values. For general prisoners' dilemma games the mediation value is ∞, the enforcement value is 2. This also holds for the class of separable prisoners’ dilemma games.

Investigation of the causes of serious injury and fatal crashes: An analysis using econometric models

The rate of fatal crashes in Florida has remained significantly higher than the national average for the last several years. The 2003 statistics from the National Highway Traffic Safety Administration (NHTSA), the latest available, show a fatality rate in Florida of 1.71 per 100 million vehicle-miles traveled compared to the national average of 1.48 per 100 million vehicle-miles traveled. The objective of this research is to better understand the driver, environmental, and roadway factors that affect the probability of injury severity in Florida. ^ In this research, the ordered logit model was used to develop six injury severity models; single-vehicle and two-vehicle crashes on urban freeways and urban principal arterials and two-vehicle crashes at urban signalized and unsignalized intersections. The data used in this research included all crashes that occurred on the state highway system for the period from 2001 to 2003 in the Southeast Florida region, which includes the Miami-Dade, Broward and Palm Beach Counties.^ The results of the analysis indicate that the age group and gender of the driver at fault were significant factors of injury severity risk across all models. The greatest risk of severe injury was observed for the age groups 55 to 65 and 66 and older. A positive association between injury severity and the race of the driver at fault was also found. Driver at fault of Hispanic origin was associated with a higher risk of severe injury for both freeway models and for the two-vehicle crash model on arterial roads. A higher risk of more severe injury crash involvement was also found when an African-American was the at fault driver on two-vehicle crashes on freeways. In addition, the arterial class was also found to be positively associated with a higher risk of severe crashes. Six-lane divided arterials exhibited the highest injury severity risk of all arterial classes. The lowest severe injury risk was found for one way roads. Alcohol involvement by the driver at fault was also found to be a significant risk of severe injury for the single-vehicle crash model on freeways. ^

The structure of games

Computer Game Playing has been an active area of research since Samuel’s first Checkers player (Samuel 1959). Recently interest beyond the classic games of Chess and Checkers has led to competitions such as the General Game Playing competition, in which players have no beforehand knowledge of the games they are to play, and the Computer Poker Competition which force players to reason about imperfect information under conditions of uncertainty. The purpose of this dissertation is to explore the area of General Game Playing both specifically and generally. On the specific side, we describe the design and implementation of our General Game Playing system OGRE. This system includes an innovative method for feature extraction that helped it to achieve second and fourth place in two international General Game Playing competitions. On the more general side, we also introduce the Regular Game Language, which goes beyond current works to provide support for both stochastic and imperfect information games as well as the more traditional games.

The Security Challenges for the 2016 Rio de Janeiro Olympic Games

Brazilians greeted the long-awaited decision of making Rio de Janeiro the host of the 2016 Olympic Games with tremendous exhilaration. Although Rio’s fantastic natural beauty certainly added to its attraction in hosting the games, its alarming rates of urban crime and violence largely associated with drug trafficking immediately triggered worldwide criticism, and put at issue its ability to guarantee the security for the games. Brazilians have been vying for a position as an emerging global economy and understand the importance of the Games for international prestige. This makes the stakes very high when hosting the Olympic Games in the wake of the 2014 Soccer World Cup, which will also be held in Brazil. This paper explores these criticisms and assesses Rio’s ability to prepare for this important event. The paper further explores the consensus that Brazilians will be more equipped to address actions taken by organized crime capable of affecting the Olympic Games than to face a terrorist attack. Brazil – and Rio – does not figure in the “terrorism map” as a region particularly linked to terrorism. Aside from uncorroborated suspicions of activities by terrorist organizations on the Tri-Border region (Argentina, Brazil, and Paraguay), Brazil does not elicit many concerns regarding terrorism.1 Yet, there is no way to guarantee that terrorist organizations will not try to make use of the 2016 Rio Olympic Games to advance their agenda. This being in mind, Rio and Brazil in general face a long road ahead to prepare, prevent, protect and respond to a possible terrorist attack during the 2016 Olympics. It is clear that prevention and preparation towards potential threats to the Games must necessarily include cooperation and exchange of best practices with other countries. 1 U.S. Department of State has confirmed that this area may have been used to transport weapons and conduct financial affairs in the past. This type of activity has been made more difficult with the fortification of border controls in more recent times.

The Dangerous Games of Fantasy, Lecture by Daína Chaviano

This flyer promotes the event "The Dangerous Games of Fantasy, Lecture by Daína Chaviano", cosponsored by the FIU Modern Languages Department and the Cuban Research Institute.

The Structure of Games

Computer Game Playing has been an active area of research since Samuel’s first Checkers player (Samuel 1959). Recently interest beyond the classic games of Chess and Checkers has led to competitions such as the General Game Playing competition, in which players have no beforehand knowledge of the games they are to play, and the Computer Poker Competition which force players to reason about imperfect information under conditions of uncertainty. The purpose of this dissertation is to explore the area of General Game Playing both specifically and generally. On the specific side, we describe the design and implementation of our General Game Playing system OGRE. This system includes an innovative method for feature extraction that helped it to achieve second and fourth place in two international General Game Playing competitions. On the more general side, we also introduce the Regular Game Language, which goes beyond current works to provide support for both stochastic and imperfect information games as well as the more traditional games.

Colgate games 200 meter race at Madison Square Garden

General note: Title and date provided by Bettye Lane.

West Point Basketball team between games

General note: Title and date provided by Bettye Lane.