Distributed knowledge
Distributed knowledge is a term used in multi-agent system research that refers to all the knowledge that a community of agents possesses and might apply in solving a problem. Distributed knowledge is approximately what "a wise man knows" or what someone who has complete knowledge of what each member of the communities knows. Distributed knowledge might also be called the aggregate knowledge of a community, as it represents all the knowledge that a community might bring to bear to solve a problem. Other related phrasings include cumulative knowledge, collective knowledge, pooled knowledge, or the wisdom of the crowd. Distributed knowledge is the union of all the knowledge of individuals in a community.
Example
The logicians Alice and Bob are sitting in their dark office wondering whether or not it is raining outside. Now, none of them actually knows, but Alice knows something about her friend Carol, namely that Carol wears her blue coat if and only if it is raining. Bob does not know this, but he just saw Carol, and noticed that she was wearing her blue coat. Even though none of them knows whether or not it is raining, it is distributed knowledge amongst them that it is raining. If either one of them tells the other what they know, it will be clear to the other that it is raining.
Distributed knowledge is related to the concept The Wisdom of the Crowds. Distributed knowledge reflects the fact that "no one of us is as smart as all of us."
In contrast, common knowledge refers to knowledge that all agents know, all agents know all agents know, all agents know all agents know all agents know, ad infinitum. Distributed knowledge is often confused with the term dispersed knowledge from economics. However, dispersed knowledge is information that is widely available, and hence more like common knowledge.
References
- R. Fagin, J. Y. Halpern, Y. Moses, and M. Y. Vardi. Reasoning about Knowledge, The MIT Press, 1995. ISBN 0-262-56200-6