2024-03-28T13:21:37Z
http://eprints.biblio.unitn.it/cgi/oai2
oai:eprints.biblio.unitn.it:28
2012-02-28T14:14:51Z
7374617475733D696E7072657373
7375626A656374733D51:5141:5141323639
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Routines, Hierarchies of Problems, Procedural Behaviour: Some Evidence From Experiments
Egidi, Massimo
QA269 Game theory
HB Economic Theory
A laboratory experiment was performed as replication of the original one created by M. Cohen and P. Bacdayan at Michigan University. It consists in a twopersons card game played by a large number of pairs, whose actions are stored in a computer’s memory. In order to achieve the final goal each player must discover his sub-goals, and must coordinate his action with the partner’s one. The game therefore involves the division of knowledge and cooperation among players, and gives rise to the emergence of organizational routines. It is suggested that the organizational routines, i.e. the sequences of patterned actions which lead to the realization of the final goal, cannot be fully memorized because of their variety and number. It is shown that players do not possess all the knowledge needed by an hypothetical supervisor to play the best strategy: they generally explore only a limited part of the space of the potential rules, and therefore learn and memorize a simple, bounded set of "personal" meta-rules. These meta-rules, also called "production rules" in standard Cognitive Science’s language, are of the form <If "Condition" then "Action">. Each "Condition" can concern either the game configurations or the partner’s action. In the former case the identification of an appropriate "Action" depends on the sub-goals exploration. In the latter it depends on the recognition (or discovery) of interaction rules ; in this eventuality the production rule embodies a dynamic - and possibly cooperative - reaction to the partner’s action. Organizational procedures (routines) therefore emerge as the outcome of a distributed process generated by "personal" production rules . These routines, as in von Hayek’s view, "can be understood as if it were made according to a single plan, although nobody has planned it." (Hayek, 1980, p. 54). Empirical evidence is provided to support the above statements.
1995
Departmental Technical Report
NonPeerReviewed
application/pdf
http://eprints.biblio.unitn.it/28/1/CEEL95_03.pdf
Egidi, Massimo (1995) Routines, Hierarchies of Problems, Procedural Behaviour: Some Evidence From Experiments. UNSPECIFIED. (In Press)
http://eprints.biblio.unitn.it/28/
oai:eprints.biblio.unitn.it:40
2012-02-28T14:14:59Z
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The reduction of decision complexity: normative policies and the role of information
Mittone, Luigi
QA269 Game theory
HB Economic Theory
No abstract available
1997
Departmental Technical Report
NonPeerReviewed
application/pdf
http://eprints.biblio.unitn.it/40/1/CEEL97_01.pdf
Mittone, Luigi (1997) The reduction of decision complexity: normative policies and the role of information. UNSPECIFIED. (Unpublished)
http://eprints.biblio.unitn.it/40/
oai:eprints.biblio.unitn.it:47
2012-02-28T14:15:00Z
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Representing others' preferences in mixed motive games: was Schelling right?
Devetag, Giovanna
Warglien, Massimo
QA269 Game theory
HB Economic Theory
The available experimental evidence suggests that even two-person normal form games with an elementary action space present substantial degrees of cognitive difficulty. We submit that the relational structure of the players' preferences is a source of complexity of a game. We provide a formal classication of order structures in two-person normal form games, based on the two properties of monotonicity and projectivity, and present an experiment on individual ability to construct a representation of bi-ordered sets isomorphic to the preference structure of paradigmatic normal form games. Experimental results support the hypothesis that relational complexity matters. In particular, they support Schelling's intuition that `mixed motive games' are harder to represent than `pure motive' ones. In addition, the experiment shows that most subjects tend to perceive and extract monotonic relations from non-projective ones. We show that individuals' short term memory capacity limitations signicantly affect their ability to correctly represent bi-orders. Some connections with Rubinstein's analysis of binary relations in natural language are also shortly discussed. JEL codes: C70, C72
2002
Departmental Technical Report
NonPeerReviewed
application/pdf
http://eprints.biblio.unitn.it/47/1/CEEL02_08.pdf
Devetag, Giovanna and Warglien, Massimo (2002) Representing others' preferences in mixed motive games: was Schelling right? UNSPECIFIED. (Unpublished)
http://eprints.biblio.unitn.it/47/
oai:eprints.biblio.unitn.it:183
2012-02-28T14:15:29Z
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Precedent transfer in coordination games: experimental evidence
Devetag, Giovanna
QA269 Game theory
HB Economic Theory
In this work we study the power of precedent transfer in improving coordination in the minimum effort game with large groups. We test whether groups which play a different coordination game in which chances to reach the best equilibrium are higher than in the minimum effort game can then transfer the homegrown precedent of e±ciency to the minimum e®ort game, achieving better coordination results compared to baseline treatments. We also test whether the opposite holds, i.e., whether ine±cient precedents achieved by groups in the minimum effort game negatively a®ect the subsequent probability of reaching the e±cient equilibrium in similar games. Our results show that e±cient precedents are generally transferred successfully to the minimum effort game, allowing groups to achieve better equilibrium outcomes compared to standard results.
2002
Departmental Technical Report
NonPeerReviewed
application/pdf
http://eprints.biblio.unitn.it/183/1/CEEL02_07.pdf
Devetag, Giovanna (2002) Precedent transfer in coordination games: experimental evidence. UNSPECIFIED. (Unpublished)
http://eprints.biblio.unitn.it/183/
oai:eprints.biblio.unitn.it:330
2012-02-28T14:16:07Z
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Games and Phone Numbers: Do Short Term Memory Bounds Affect Strategic Behavior?
Devetag, Giovanna
Warglien, Massimo
QA269 Game theory
HB Economic Theory
Research in experimental and behavioral game theory has revealed a substantial and persistent degree of heterogeneity in the strategic behavior of real individuals. While the prevailing theoretical explanations of the observed heterogeneity typically invoke underlying differences in beliefs among the population of players, we argue that a further source of heterogeneity may consist in the individuals’ different ability to process information, of which short term memory capacity provides a measurable proxy. Research in cognitive psychology has shown that individuals typically differ in their short term memory capacity; furthermore, short term memory capacity provides a fundamental cognitive bottleneck to our ability to process information e±ciently and hence seems correlated with performance in a variety of problem solving and reasoning tasks. In this paper we conduct experiments on a set of well-known games whose solution concepts require the application of some paradigmatic forms of strategic reasoning, such as iterated dominance and backward induction. We separately conduct standard short term memory tests on our subjects to detect the presence of a correlation between individuals’ behavior in the games - here defined in terms of degrees of conformity to the standard game-theoretic prescriptions - and their short term memory score. Our results show the presence of a significant and positive correlation between subjects’ short term memory score and conformity to standard game-theoretic prescriptions in the games, thus confirming our hypothesis. While the robustness of our conjecture awaits to be confirmed by further data gathering in more interactive experimental settings, our preliminary results suggest a promising line of inquiry on the interconnections between information processing capacity and strategic behavior.
2002
Departmental Technical Report
NonPeerReviewed
application/pdf
http://eprints.biblio.unitn.it/330/1/papero02_11.pdf
Devetag, Giovanna and Warglien, Massimo (2002) Games and Phone Numbers: Do Short Term Memory Bounds Affect Strategic Behavior? UNSPECIFIED. (Unpublished)
http://eprints.biblio.unitn.it/330/
oai:eprints.biblio.unitn.it:331
2012-02-28T14:16:07Z
7374617475733D756E707562
7375626A656374733D51:5141:5141323639
7375626A656374733D48:4842
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Rethinking Bounded Rationality
Egidi, Massimo
QA269 Game theory
HB Economic Theory
[From the "Introduction"] In some contexts, like for example complex games and puzzles, the search of solutions for problems leads to discover different procedures, none of which can be considered “the best” one. In these contexts, in fact, the different solutions can be compared only in some specific well known domain of application, while in other domains the comparison is incomplete or vague, or the domain may have imperfectly known boundaries: it is therefore impossible to put the different procedures in a precise preference order over the entire domain of applicability. Moreover these procedures may be “locally stable” because small local changes in the instructions that define them do not lead to any improvement, and therefore individuals that discover one solution may remain locked in it without trying to search alternative solutions. The search of solutions in puzzles shows striking analogies with the search of new theoretical approaches that take place when a consolidated theory fails to explain new phenomena. The properties of search in puzzles – multiplicity, local stability and incompleteness of solutions – also affect the new theoretical approaches, i.e. the new solutions to a scientific puzzle, that emerge challenging a dominant theory. (...)
2002
Departmental Technical Report
NonPeerReviewed
application/pdf
http://eprints.biblio.unitn.it/331/1/papero02_12.pdf
Egidi, Massimo (2002) Rethinking Bounded Rationality. UNSPECIFIED. (Unpublished)
http://eprints.biblio.unitn.it/331/
oai:eprints.biblio.unitn.it:332
2012-02-28T14:16:07Z
7374617475733D756E707562
7375626A656374733D51:5141:5141323639
7375626A656374733D48:4842
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Overcontribution and decay in public goods experiments: a test of the heterogeneous agents hypothesis
Burlando, Roberto M.
Guala, Francesco
QA269 Game theory
HB Economic Theory
standard attempts to explain the phenomenon of decaying contribution in repeated linear public goods games are based on a ‘representative agent’ approach, with either selfish or altruist agents and an ‘error’ component. In this paper we try to test by purely experimental means the alternative hypothesis that in experimental public goods games there are at least three types of player: free riders, cooperators, and reciprocators. We try to identify the various types by means of four classification methods, and then play the public goods game with homogeneous groups. We observe that (1) the average contribution level is enhanced in this setting; (2) the decay phenomenon is replicated in groups of ‘pure’ free riders, whereas in groups of cooperative and reciprocating players the contribution is high and fairly stable throughout the game.
2002
Departmental Technical Report
NonPeerReviewed
application/pdf
http://eprints.biblio.unitn.it/332/1/papero02_13.pdf
Burlando, Roberto M. and Guala, Francesco (2002) Overcontribution and decay in public goods experiments: a test of the heterogeneous agents hypothesis. UNSPECIFIED. (Unpublished)
http://eprints.biblio.unitn.it/332/
oai:eprints.biblio.unitn.it:333
2012-02-28T14:16:08Z
7374617475733D756E707562
7375626A656374733D51:5141:5141323639
7375626A656374733D48:4842
74797065733D746563687265706F7274
Coordination and information in critical mass games: an experimental study
Devetag, Giovanna
QA269 Game theory
HB Economic Theory
We present experimental results on a repeated coordination game with Pareto-ranked equilibria in which a payoff from choosing an action is positive only if a critical mass of players choose that action. We design a baseline version of the game in which payoffs remain constant for values above the critical mass, and an increasing returns version in which payoffs keep increasing for values above the critical mass. We test the predictive power of security and payoff-dominance under different information treatments. Our results show that convergence to the payoff-dominant equilibrium is the modal limit outcome when players have full information about others’ previous round choices, while this outcome never occurs in the remaining treatments. The paths of play in some groups reveal a tacit dynamic coordination by which groups converge to the e±cient equilibrium in a step-like manner. Moreover, the frequency and speed of convergence to the payoff-dominant equilibrium are higher, ceteris paribus, when increasing returns are present. Finally, successful coordination seems to crucially depend on players’ willingness to signal to others the choice of the action supporting the effcient equilibrium.
2002
Departmental Technical Report
NonPeerReviewed
application/pdf
http://eprints.biblio.unitn.it/333/1/papero02_14.pdf
Devetag, Giovanna (2002) Coordination and information in critical mass games: an experimental study. UNSPECIFIED. (Unpublished)
http://eprints.biblio.unitn.it/333/
oai:eprints.biblio.unitn.it:334
2012-02-28T14:16:08Z
7374617475733D756E707562
7375626A656374733D51:5141:5141323639
7375626A656374733D48:4842
74797065733D746563687265706F7274
Coordination and self-organization in minority games: experimental evidence
Bottazzi, Giulio
Devetag, Giovanna
QA269 Game theory
HB Economic Theory
This work presents experimental results on a coordination game in which agents must repeatidly choose between two sides, and a positive fixed payoff is assigned only to agents who pick the minoritarian side. We conduct laboratory experiments in which stationary groups of five players play the game for 100 periods, and manipulate two treatment variables: the amount of 'memory' M that players have regarding the game history (i.e. , the length of the string of past outcomes that players can see on the screen while choosing), and the amount of information about other players' past choices. Our results show that, at the aggregate level, a quite remarkable degree of coordination is achieved. Moreover providing players with full information about other players' choice distribution does not appear to improve efficiency significantly. At the individual level, a substantial portion of subjects exhibit 'inertal' behavior.
2002
Departmental Technical Report
NonPeerReviewed
application/pdf
http://eprints.biblio.unitn.it/334/1/papero02_15.pdf
Bottazzi, Giulio and Devetag, Giovanna (2002) Coordination and self-organization in minority games: experimental evidence. UNSPECIFIED. (Unpublished)
http://eprints.biblio.unitn.it/334/
oai:eprints.biblio.unitn.it:389
2012-02-28T14:16:25Z
7374617475733D756E707562
7375626A656374733D51:5141:5141323639
7375626A656374733D48:4842:4842313331
74797065733D61727469636C656A6F75726E616C
Adaptive learning and emergent coordination in minority games
Bottazzi, Giulio
Devetag, Giovanna
Dosi, Giovanni
QA269 Game theory
HB131 Methodology
The work studies the properties of a coordination game in which agents repeatedly compete to be in the population minority. The game re ects some essential features of those economic situations in which positive rewards are assigned to individuals who behave in opposition to the modal behavior in a population. Here we model a group of heterogeneous agents who adaptively learn and we investigate the transient and long-run aggregate properties of the system in terms of both allocative and informational efficiency. Our results show that, first, the system long-run properties strongly depend on the behavioral learning rules adopted, and, second, adding noise at the individual decision level and hence increasing heterogeneity in the population substantially improve aggregate welfare, although at the expense of a longer adjustment phase. In fact, the system achieves in that way a higher level of efficiency compared to that attainable by perfectly rational and completely informed agents.
Università degli Studi di Trento
2001-01
Article in journal
NonPeerReviewed
application/pdf
http://eprints.biblio.unitn.it/389/1/BDD_alec.pdf
Bottazzi, Giulio and Devetag, Giovanna and Dosi, Giovanni (2001) Adaptive learning and emergent coordination in minority games. In «ROCK Working Papers», Università degli Studi di Trento. (Unpublished)
http://eprints.biblio.unitn.it/389/
oai:eprints.biblio.unitn.it:391
2012-02-28T14:16:27Z
7374617475733D756E707562
7375626A656374733D51:5141:5141323639
7375626A656374733D48:4842:4842313331
74797065733D61727469636C656A6F75726E616C
An experimental investigation of fairness and reciprocal behavior in a triangular principal-multiagent relationship
Rossi, Alessandro
Warglien, Massimo
QA269 Game theory
HB131 Methodology
Issues of fairness in hierarchies have been mostly investigated - both theoretically and experimentally - within dyadic principle-agent relationships. In this paper we consider triangular principal-multiagents structures, integrating vertical hierarchical relationships with horizontal agent-to-agent ones. We explore in the laboratory a game that allows to investigate how principal's fairness affects cooperation between two interdependent agents performing a simple production task. Our experimental findings show that perceived fairness of principal's actions may trigger reciprocation in agent's behavior, affecting how agents play the production game.
Università degli Studi di Trento
2001-06
Article in journal
NonPeerReviewed
application/pdf
http://eprints.biblio.unitn.it/391/1/RW_inv.pdf
Rossi, Alessandro and Warglien, Massimo (2001) An experimental investigation of fairness and reciprocal behavior in a triangular principal-multiagent relationship. In «ROCK Working Papers», Università degli Studi di Trento. (Unpublished)
http://eprints.biblio.unitn.it/391/
oai:eprints.biblio.unitn.it:398
2012-02-28T14:16:27Z
7374617475733D756E707562
7375626A656374733D51:5141:5141323639
74797065733D61727469636C656A6F75726E616C
An experimental investigation of fairness and reciprocal behavior in a simple principal-multiagent relationship
Rossi, Alessandro
Warglien, Massimo
QA269 Game theory
Issues of fairness within the agency framework have traditionally been investigated - both theoretically and experimentally - within two alternative approaches: a "vertical", hierarchical framework (studies of fairness in the agency relationship between one principal and one single agent) and a "horizontal", agent-to-agent framework (studies of reciprocity in peers' interactions under alternative incentive schemes). We explore in the laboratory a game which integrates vertical and horizontal relationships and allows to investigate how principal's fairness affects cooperation between two interdependent agents performing a simple production game. We set a 2-stage game where, in the second stage, agents play a prisoner's dilemma game and, in the first stage, the principal can withdraw any share of the output generated by the agents in the second stage. Despite theory predicting that no fairness should be observed by the principal and no cooperation should be observed by agents, our experimental findings show that agents are to some extent sensitive to principal's fairness. When the principal plays unfair (fair) agents are frequently observed to jointly defect (cooperate). Thus, fairness considerations on principal's actions may act as a coordination device for the agents and reciprocal behavior may, as a result, affect their propensity towards cooperation or defection in the game.
Università degli Studi di Trento
2000-03
Article in journal
NonPeerReviewed
application/pdf
http://eprints.biblio.unitn.it/398/1/RW_Triangles.pdf
Rossi, Alessandro and Warglien, Massimo (2000) An experimental investigation of fairness and reciprocal behavior in a simple principal-multiagent relationship. In «ROCK Working Papers», Università degli Studi di Trento. (Unpublished)
http://eprints.biblio.unitn.it/398/
oai:eprints.biblio.unitn.it:399
2012-08-02T12:30:22Z
7374617475733D756E707562
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74797065733D61727469636C656A6F75726E616C
Stochastic learning in co-ordination games : a simulation approach
Zaninotto, Enrico
Rossi, Alessandro
Gaio, Loris
QA269 Game theory
In the presence of externalities, consumption behaviour depends on the solution of a co-ordination problem. In our paper we suggest a learning approach to the study of co-ordination in consumption contexts where agents adjust their choices on the basis of the reinforcement (payoff) they receive during the game. The results of simulations allowed us to distinguish the roles of different aspects of learning in enabling co-ordination within a population of agents. Our main results highlight: 1. the role played by the speed of learning in determining failures of the co-ordination process; 2. the effect of forgetting past experiences on the speed of the co-ordination process; 3. the role of experimentation in bringing the process of co-ordination into an efficient equilibrium.
Università degli Studi di Trento
1999-03
Article in journal
NonPeerReviewed
application/pdf
http://eprints.biblio.unitn.it/399/1/zrgstochastic.pdf
Zaninotto, Enrico and Rossi, Alessandro and Gaio, Loris (1999) Stochastic learning in co-ordination games : a simulation approach. In «ROCK Working Papers», Trento : Università degli Studi di Trento. (Unpublished)
http://eprints.biblio.unitn.it/399/
oai:eprints.biblio.unitn.it:400
2012-02-28T14:16:28Z
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7375626A656374733D48:4842
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On bubbling dynamics generated by a stochastic model of herd behavior
Gaio, Loris
Kaniovski, Yuri M.
Zaninotto, Enrico
QA269 Game theory
HB Economic Theory
This paper suggests a class of stochastic collective learning processes exhibiting very irregular behavior. In particular, there are multimodal long run distributions. Some of these modes may vanish as the population size increases. This may be thought of as "bubbles" persistent for a finite range of population sizes but disappearing in the limit. The limit distribution proves to be a discontinuous function of parameters determining the learn- ing process. This gives rise to another type of "bubbles": limit outcomes corresponding to small perturbations of parameters are different. Since an agent's decision rule involves imitation of the majority choice in a random sample of other members of the population, the resulting collective dynamics exhibit "herding" or "epidemic" features.
Università degli Studi di Trento
1999-03
Article in journal
NonPeerReviewed
application/pdf
http://eprints.biblio.unitn.it/400/1/techrep.pdf
Gaio, Loris and Kaniovski, Yuri M. and Zaninotto, Enrico (1999) On bubbling dynamics generated by a stochastic model of herd behavior. In «ROCK Working Papers», Università degli Studi di Trento. (Unpublished)
http://eprints.biblio.unitn.it/400/
oai:eprints.biblio.unitn.it:403
2012-02-28T14:16:29Z
7374617475733D756E707562
7375626A656374733D51:5141:5141323639
7375626A656374733D48:4842
74797065733D61727469636C656A6F75726E616C
Probabilistic learning and emergent coordination in a non-cooperative game with heterogeneous agents : an exploration of "minority game" dynamics
Bottazzi, Giulio
Devetag, Giovanna
QA269 Game theory
HB Economic Theory
In this paper we present results of simulations in which we use a general probabilistic learning model to describe the behavior of heterogeneous agents in a non-cooperative game where it is rewarding to be in the minority group. The chosen probabilistic model belongs to a well-known class of learning models developed in evolutionary game theory and experimental economics, which have been widely applied to describe human behavior in experimental games. We test the aggregate properties of this population of agents (i.e., presence of emergent cooperation, asymptotic stability, speed of convergence to equilibrium) as a function of the degree of randomness in the agents' behavior. In this way we are able to identify what properties of the system are sensitive to the precise characteristics of the learning rule and what properties on the contrary can be considered as "generic" features of the game. Our results indicate that, when the degree of "inertia" of the learning rule increases, the market reaches a higher level of allocative and informational efficiency, although on a longer time scale.
Università degli Studi di Trento
1999-08
Article in journal
NonPeerReviewed
application/pdf
http://eprints.biblio.unitn.it/403/1/BD_probabilistic.pdf
Bottazzi, Giulio and Devetag, Giovanna (1999) Probabilistic learning and emergent coordination in a non-cooperative game with heterogeneous agents : an exploration of "minority game" dynamics. In «ROCK Working Papers», Università degli Studi di Trento. (Unpublished)
http://eprints.biblio.unitn.it/403/
oai:eprints.biblio.unitn.it:1436
2012-02-28T14:21:47Z
7374617475733D756E707562
7375626A656374733D51:5141:5141323639
7375626A656374733D51:5141:51333630
7375626A656374733D54:544B:544B37383835
7375626A656374733D54:544B:544B353130352E35
7375626A656374733D51:5141:51413735
74797065733D746563687265706F7274
Analysis of TCP/MAC Interactions Using the Game Theory
Facchini, Christian
Granelli, Fabrizio
QA269 Game theory
TK7885 Computer Engineering
Q360 Information Theory
TK5105.5 Computer Networks
QA075 Electronic computers. Computer science
ISO/OSI and TCP/IP protocol stacks provide networks and devices interoperability by exploiting the principle of layering, where every layer is characterized by specific functionalities and is allowed to interact only with adjacent layers by means of standardized interfaces. However, while such principle provides freedom in implementation of the protocols at different layers, it limits the control on the interaction among protocols at different layers. In this framework, it is necessary to develop efficient model to capture the interaction of protocols with a single communication device in order to underline such forms of “indirect” interaction – which may lead to unforeseen performance degradations. The proposed work aims at proposing the usage of the game theory for capturing the interactions within the protocol stack of a single node, with the goal of allowing to determine the “steady state” or the operating point of the system in a given scenario (TCP over IEEE 802.11).
2008-05
Departmental Technical Report
NonPeerReviewed
application/pdf
http://eprints.biblio.unitn.it/1436/1/DISI%2D08%2D025.pdf
Facchini, Christian and Granelli, Fabrizio (2008) Analysis of TCP/MAC Interactions Using the Game Theory. UNSPECIFIED. (Unpublished)
http://eprints.biblio.unitn.it/1436/
oai:eprints.biblio.unitn.it:1660
2012-10-24T11:09:34Z
7374617475733D756E707562
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Collusion in Peer-to-Peer Systems
Lo Cigno, Renato
Ciccarelli, Gianluca
QA269 Game theory
QA075 Electronic computers. Computer science
Peer-to-peer systems have reached a widespread use, ranging from academic and industrial applications to home entertainment. The key advantage of this paradigm lies in its scalability and flexibility, consequences of the participants sharing their resources for the common welfare. Security in such systems is a desirable goal. For example, when mission-critical operations or bank transactions are involved, their effectiveness strongly depends on the perception that users have about the system dependability and trustworthiness. A major threat to the security of these systems is the phenomenon of collusion. Peers can be selfish colluders, when they try to fool the system to gain unfair advantages over other peers, or malicious, when their purpose is to subvert the system or disturb other users. The problem, however, has received so far only a marginal attention by the research community. While several solutions exist to counter attacks in peer-to-peer systems, very few of them are meant to directly counter colluders and their attacks. Reputation, micro-payments, and concepts of game theory are currently used as the main means to obtain fairness in the usage of the resources. Our goal is to provide an overview of the topic by examining the key issues involved. We measure the relevance of the problem in the current literature and the effectiveness of existing philosophies against it, to suggest fruitful directions in the further development of the field.
2009-08
Departmental Technical Report
NonPeerReviewed
application/pdf
http://eprints.biblio.unitn.it/1660/1/collp2p.pdf
Lo Cigno, Renato and Ciccarelli, Gianluca (2009) Collusion in Peer-to-Peer Systems. UNSPECIFIED. (Unpublished)
http://eprints.biblio.unitn.it/1660/