social welfare. It does not consider how much the other agent
would potentially gain as a result of a special commitment,
because the other agent’s potential gain is not thought by this
agent as a reliable factor that indicates of social welfare, this
agent rather leaves the information out of its consideration.
We feel that as the sophistication of multi-agent systems
increases, MAS will be neither simple market systems where
each agent is purely self-interested, seeking to maximize its
local utility, nor distributed problem solving systems where all
agents are completely cooperative working to maximize their
joint utility. This will occur for the following reasons. First,
agents from different separate organizational entities will come
together to dynamically form virtual organizations/teams for
solving specific problems that are relevant to each of their
organizational entities [10]. How these agents work in their
teams will often be dependent on the existence of both longterm
and short-term relationships that are based on the goals
of their underlying organizational entities. Secondly, even
for agents from organizations with meta-goals that indicate
self-interestedness, it might be beneficial for them to be
partially externally-directed when they are in the situations
where they will have repeated transactions with other agents
from other organizational entities. Additionally, even agents
working solely with agents of their own organizational entities
will take varying negotiation attitudes in the spectrum of
completely externally-directed to completely self-directed in
order for the organization to best achieve its overall goal. The
latter perspective is based on a bounded-rational argument: it
is not possible from a computational or communicational
perspective for an agent to be fully cooperative, because
the agent needs to take into account the current and expected
change in the utilities of all agents in the organization and
the state of achievement of all organizational goals to be
fully cooperative. Thus, it may be best for the organization
to have agents being partially externally-directed in their local
negotiation with other agents rather than being completely
externally-directed in order to deal more effectively with the
uncertainty of not having a more informed view of the state
of the entire agent organization. We feel a similar argument
can be made for self-interested agents. It may not always
be advantageous for them to take the negotiation attitude of
completely self-directed. Rather, in some context, the more
external-directed attitude will lead to an increase in their own
local utility.
Note that this work pertains to deliberate agents situated in
an agent society where there are organizational relationships
among agents. The agents can make choices about with whom
to collaborate, how to negotiate, what to charge for services,
etc. Further, the negotiation attitude will be dependent on the
relationships among the negotiating parties and the particular
negotiation issue, and the state of achievement of relevant
organizational goals. In the experimental work reported in this
paper, we are also assuming that agents are not acting in a
hostile manner nor gaming the situation based on the metalevel
information transferred among agents. However, we feel
that by adding some additional mechanisms that allow an agent
to adjust the character of the meta-level information that is
exchanged, hostile/gaming agents can be handled within the
basic framework laid out in this paper.
Let’s consider the supply chain example in Figure 1. There
are different organizational relationships among agents. For
instance, there is an agent (agent IBM 2) who produces hard
drives, belonging to the IBM Company. It provides hard drives
for three different agents, with the following organizational
relationships to it:
1) Agent IBM 2 provides hard drives for the other agent
(agent IBM 1), which also belongs to IBM but assembles
PCs.
2) Agent IBM 2 provides hard drives to an NEC agent
(agent NEC), and as the transactions between them
become more frequent and regular, they form a virtual
organization based on the recent transactions.
3) Agent IBM 2 occasionally provides hard drives for a
distributor center (agent DIS) based on a simple marketlike
mechanism.
When agent IBM 2 negotiates with these three agents, it
should use different negotiation attitudes that reflects the
different relationships. For instance, when it negotiates with
agent IBM 1, it may need to be more externally-directed than
it is towards the other two agents if its most important metagoal
is to increase the utility of IBM. However, even for the
good of IBM’s benefit, it may not be the best choice for
agent IBM 2 always to be completely externally-directed towards
agent IBM 1. Sometimes it may bring IBM more profit
for agent IBM 2 to provide hard drives to agent DIS rather
than to agent IBM 1, if agent IBM 1 is not certain whether it
really needs the hard drive.
When agent IBM 2 negotiates with agent NEC, it may need
to be more externally-directed than it is towards agent DIS
given the virtual organization it has formed with agent NEC.
The appropriate level of local cooperation depends on how
important the utility increase of this virtual organization is to
agent IBM 2, how the goal to increase the utility of this virtual
organization relates to its other goals, and how certain the
information provided by agent DIS compares to the information
received from other sources. Also, as we noticed before,
the formation of this virtual organization is dynamic; it may
also disappear sometime later as the environment changes, so
agent IBM 2 should adapt its negotiation attitude dynamically
too.
From the above examples we find it necessary to have
a mechanism that supports agents choosing from among
many different negotiation attitudes in the spectrum from
completely self-directed to completely externally-directed, and
easily switching from one attitude to another. The choice of negotiation
attitude should depend on the agent’s organizational
goals, the current environmental circumstance, which agent it
is negotiating with, and what issue is under negotiation. There
should also be no requirement of a centralized controller that
coordinates the agent’s behavior.
So far, there has been no such negotiation mechanism which
provides the above capabilities for agents (see related work in
Section VI). In this paper, we introduce an negotiation mechanism
which enables agents to construct negotiation attitudes
in the spectrum from completely self-directed to completely
externally-directed in a uniform reasoning framework called