Here we sketch on some possible mechanisms for social control that are inspired by establishing opinions about the other group members. These are either local to each individual, distributed or trusted to a third part.
Figure 9: The seller is offering money back, using a trusted third part
When a new agent is introduced to the market it has no reputation and therefore it is highly unlikely that anyone will use it. The agent can promote itself by giving a ``money back guarantee'' and leaving the money to a third, trusted part. Therefore the agent needs some initial capital as an insurance for its client, but gradually, as the reputation builds up, this will be less and less necessary. The value will be in the reputation, and loss of this reputation will be at least to the cost of the interest of lending the money to build up the reputation (not counting the cost of the profitable deals that could be made using that reputation).
Figure 10: The actors can themselves spread the rumour about bad agents.
If an agent discovered a good cooperating partner it could inform the other agents about it, and likewise if it had been cheated. The agents gossip about each other. This quickly ruins the local market for a malicious agent.
However, in ecologic systems, the ones who are to gain the most from this information is by large probability the competitors to the gossiping agent, and therefore an agent might be better of by lying. This is the paradox of altruistic communication, which usually ends up in no communication at all.
The question about how the gossip spreads in the global society is also unclear. If the agents have low or none incentive to move around, actors who move faster that its rumour can find new clients.
Figure 11: A reviewer can maintains a list of reputations
If we introduce actors who are concerned with the maintenance of reputation of others they can charge others for giving them advice on whom to choose for a particular task. These reputation agents can use the money to buy services from the vending agents. This idea is very similar to that of restaurant critics, and for them, as well as for agents, it is very important that they act incognito. If they weren't incognito they might get a special treatment and they would be unable to give a correct judgment.
It has been suggested [6] that for ideal critics reviews the buyer has a large incentive to be anonymous (otherwise he/she can't trust reviews as a means to find good deals), and the (non-malicious) seller has every reason to prove his identity to the buyers. Otherwise he/she won't get the credit he/she deserves.
Reputation is in many cases a subjective measure, as was exemplified above with the example about music. By permitting different reputation scales to co-exist and compete, it will be possible to use the reputation mechanism as a tool for finding and categorising information. Variations of this idea is today tried for filtering Usenet news.
Possibly reputation can be used in self-improving systems where the reputation corresponds to how well a service is performed [5]. Actors who's services perform badly compared to others' will gradually be replaced by the services of actors with better reputation.
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Lars Rasmusson
