An agent type is such that an agent is capable of putting forward only a subset of all possible arguments in the argumentation framework. The notion of defeat (i.e. the defeat relation) is assumed common to all agents.
The kind of manipulation (lying) considered is that wherein agents hide some of their arguments. ("By refusing to reveal certain arguments, an agent might be able to break defeat chains in the argument framework, thus changing the final set of acceptable arguments.") An external verifier is assumed so that agents cannot create new arguments that they do not have in their argument set.
Reiterating, the key assumptions are:
- There is a common language for describing/understanding arguments.
- The defeat relation is common knowledge.
- The set of all possible arguments that might be presented is common knowledge.
- Agents do not know who has what arguments.
- Not all arguments may end up being presented by their respective agents.