Massive user cooperation is essential for the performance of a P2P system. We believe incentivizing this cooperation is the key. Within Tribler we aim to create incentives for all important activities:
Such incentives can be based on very rational behavior, as studied by the field of Mechanism Design.
However, human behavior in a social context is often led by other, more emotional motivations. Social incentives provide a social reward such as higher esteem, improved group status, etc.
[MdW] For any incentivization it is important that peers know which information (about previous interactions, etc.) from which peers they can trust. There seem to be at least two directions for providing such a network of trust (also called reputation):
- use real-life social relations: you trust only opinions from your friends, and possibly (but with a lower weight) from friends of friends (etc.), or
- develop a reputation system in which bad behavior results (automatically) in a lower reputation value, and thus also in a worse quality of service provided by all peers.
For the former option quite some algorithms have been devised and this could be implemented right away. However, it requires quite some (inter)action by the users. What happens if users start adding everyone as a friend? Are users prepared to remove so-called friends when they give invalid information? Whether the latter approach provides a feasible alternative is unclear for now. The theory for centrally maintaining a reputation seems solid, see ''A Bayesian framework for online reputation systems'' by Petteri Nurmi (2006) for a survey. Whether this theory also can be applied in a distributed setting is an interesting research question. /[MdW]
Another theoretical foundation which takes into account information asymmetry, uncertainty and risk also provides a good fit. In economics, the principal-agent problem treats the difficulties that arise under conditions of incomplete and asymmetric information when a principal hires an agent. Various mechanisms may be used to try to align the interests of the agent with those of the principal, such as piece rates/commissions, profit sharing, efficiency wages, the agent posting a bond, or fear of firing. The principal-agent problem is found in most employer/employee relationships, for example, when stockholders hire top executives of corporations.
Third fit is focussed on moral hazards, incomplete contracts, etc.
Contract theory studies how economic actors can and do construct contractual arrangements, generally in the presence of asymmetric information. Contract theory is closely connected to the subfields of information economics and law and economics. One prominent field of application is managerial compensation.
David Parkes (Harvard) course on Mechanism Design with many useful documents and links
P2P Currency research
Reduction Over Time to Facilitate Peer-to-Peer Barter Relationships
"This paper describes in detail how incentive-compatibility is achieved by this extended design; we predict that the following properties will hold, which resulted from a game-theoretical analysis."
Charging in Peer-to-Peer Systems based on a Token Accounting System
Enforcing cooperative resource sharing in untrusted P2P computing environments
Off-line karma: A decentralized currency for peer-to-peer and grid applications
We present a completely decentralised, off-line karma implementation for P2P and grid systems, that detects double-spending and other types of fraud under varying adversarial scenarios. The system is based on tracing the spending pattern of coins, and distributing the normally central role of a bank over a predetermined, but random, selection of nodes.
WOT for WAT: Spinning the web of trust for peer-to-peer barter relationships
Participants spontaneously issue and circulate the tickets as needed, whose values are backed up by chains of trust. i-WAT implements the tickets electronically by exchanges of messages signed in OpenPGP . This paper clarifies the trust model of i-WAT, and investigates how it is related with that of PGP .
Light-weight currency management mechanisms in mobile and weakly-connected environments
We first give an overview of Deno, discussing its voting scheme, proxy mechanism, basic API, and commit performance. We then focus on the issue of currency management. Although there has been much work on currency management in synchronous, strongly-connected environments, this issue has not been explored in asynchronous, weakly-connected environments.