Ontologies for Agents
Each agent has to know something about a domain he is working in and also has to communicate with other agents. An agent is able to communicate only about facts that can be expressed in some ontology. This ontology must be agreed and understood among the agent community (or at least among its part) in order to enable each agent to understand messages from other agents.
Unfortunately, the "ontology" used for communication between agents is not always expressed explicitly - the constructs used to exchange information may be hardcoded in agents, and no explicit form describing the ontology may be available. The assumptions on the meaning of the vocabulary are implicitly embedded in agents, i.e., in software programs representing agents. In this case it is harder to integrate such agents with other agents that were not programmed to communicate together.
In open multi-agents systems, where agents designed by different programmers or organizations may enter into communication, the ontology must be expressed explicitly in order to enable integration. In such environment, it is also necessary to have standard mechanisms to access and refer to explicitly defined ontologies.
When multiple ontologies are used in a system, translation between ontologies is needed for agents to be able to communicate. The summary of operations on ontologies to achieve this goal as well as the summary of relations between ontologies was already presented.