MultiAgent Planning
Overview
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Why multiagent planning is needed ?
Cooperation
Multibody planning
Coordination Mechanisms
Why is multiagent planning needed?
PERFORMANCE/EFFICIENCY
• If new agents are introduced to a single agent
environment, but the single agent does not
change its basic algorithms then it may perform
poorly.
• Agents are not indifferent to another agent’s
intentions (like nature is). So Agents can
cooperate, compete, or coordinate. Sometimes
distributed computations are easier to
understand and develop.
Cooperation
• Efficient plan construction is important. Both
agents must use the same plan and coordinate
their actions and communicate to help ensure
success.
• Agents share a common goal (winning in tennis),
but can also share subgoals as well. What are
some subgoals they could share in the tennis
example?
• A joint plan can be used as a solution to a MAP
problem.
Cooperation (cont.)
• joint plan- is a plan with a set of actions for
each agent and can only be considered a
solution if the goal results from the agents
carrying out their assigned actions.
Multibody Planning
Multibody planning focuses on the construction
of correct joint plans. It allows each agent to
determine which joint plans would be successful
if carried out.
Using partial-order planning approach, the
environment is fully observable and dynamic.
Synchronization is important now that there are
more than one agent in the environment
Multibody planning (cont.)
• joint action- set of concurrent actions where
each agent executes exactly one action at a
point in time.
• Example:
<Go(A[left,net]Go(B[right,baseline])>
<NoOp(A). Hit(B,ball)>
Multibody planning (cont.)
• Concurrent action list- describes actions that must or
must not be executed concurrently.
• Example:
Hit action
Action (Hit(A, Ball),
CONCURRENT:¬ Hit (B, Ball)
PRECOND: Approaching (Ball, [x,y]) Λ At(A,[x,y])
EFFECT: Returned(Ball)).
During hit action only one agent may execute hit
Coordination Mechanisms
• Agents communicate in order to achieve the
goals of themselves or of the system in which
they exist.
• Commitments and conventions are the
cornerstones of coordination.
• Commitment- provides the necessary
structure for predictable interactions.
• Convention- provide the necessary degree of
mutual support
Coordination mechanisms (cont.)
• A convention is one of the simplest ways of
ensuring that a group of agents adopts the
same joint plan before carrying out a joint
activity.
• convention- any constraint on adopting a joint
plan that it must work if all agents adhere to
it.
• social laws- conventions that are widely
adopted.
Coordination mechanisms (cont.)
• Communication can be used in times when
conventions become inflexible or breakdown
and common knowledge needs to be
reestablished.
• What are some ways agents can
communicate to one another
• plan recognition- when one agent’s actions
determine the joint plan of the group