The second axis is the object of negotiation, i.e. what is being negotiated. For example, two agents can negotiate what to do next (negotiating action), negotiate the knowledge underlying their decisions (negotiating knowledge), negotiate how to represent this knowledge (negotiating representations), negotiate their mode of interaction (e.g. 'was that a question or a claim?', negotiating turn taking), (negotiating interaction). This dimension crosses the previous one (e.g. negotiating the next action can be done through discussion on simply by doing it). What can be considered as an object of negotiation within a specific system depends on a number of factors, principally : the nature of the task domain and the agents' respective degrees of knowledge with respect to it. Thus for domains where there exists a single 'correct' solution method, and only one of the agents knows it, then this can not (sincerely) be an object of negotiation. However, the conceptual point of view within which the domain is approached (e.g. functional, procedural, …) may still be negotiable. In more 'open' domains, where there are several possible solution methods, or where 'plausible' or 'uncertain' reasoning is required, the negotiation space on this level may be wider and more symmetrical (see below).
