Gaton, M.E. and desJardins, M., In
Proceedings of AAMAS-2005, pp. 230-237.
Agent-Organized Networks for
Dynamic Team Formation
Seo, Young-Woo
Introduction
• Agent-Oriented Network (AON)
– An organizational network structure, or agent-to-agent
interaction topology that is the result of local rewiring decisions
made by the individual agents in a networked multi-agent
system.
– Goal of the individual agents:
• Increase the collective performance of the agent organization by
rewiring of an initial (arbitrary) network topology instead of creating
and removal of connections
• Strategy Design Issues
– Local estimation of global performance
– When/How to perform network adaptation (or rewiring)
• Effectiveness of a Strategy
– Learning rate, stability, global structure
2
Dynamic Multi-Agent Formation
• A Simple Model of Multi-Agent System
– Team of agents forms a structure (or a
topology) on the fly in decentralized fashion
– Individual decision making is based on local
information
– Tasks are generated periodically and
broadcasted globally
3
A  a1 ,..., a N ,
ki 
e ,
a j A
uncommitted
ij
 i  1, |  |
Tk : task
RTk | Tk |~ U 1,  
M k : member of a team
committed
active
si: States of an individual agent ai on the
team formation
-uncommitted: available, but not assigned to any task
-committed: assigned to a task,
but the team works on the skill fulfillment on a task
-active: the team is working on the task
 : interval between ta sks
 : number tim e step of task advertisem ent
 : availabili ty period of active agents
4
A valid team is a set of agents that induce a connected subgraph of the agent
Social network and whose skill set fulfills the skill requirements for a given task.
An uncommitted agent is only eligible to a task either
initiate a team or
join a team
1
 e I s , uncommitted 
IPi 
a j A
ij
i
e
a j
i
2
ij
|Mk|
Mk
5
Rewiring Strategies (1/2)
• Structure-based
– Preferential attachment
• “Rich-Get-Richer”: A connectivity phenomenon observed in a
scale-free network
• Probability of connecting to a given node in a network is
proportional to that node’s degree
Pai  a j  
kj
k
l
al N i2
6
Rewiring Strategies (2/2)
• Performance-based
– Consider the local performance and referral
– Rewire if the local performance is below the average
of its immediate neighbors’ performance measures
1
Y ai  
ki
 Y a 
a j  A,eij 1
j
| valid team joined |
Y a j  
| team joined |
• Disconnect from the neighbor that has the lowest
performance
• Establish connection to neighbor with the highest
performance by requesting referrals
7
Experiments
• Setting
– Random geographic graph
• Randomly placing N agents in the unit square and
connecting two agents if they are within a
predefined distance d
– Actions of an individual agent
• Adapt the network / join teams
– Parameters
• N=100,  =  = σ = |T|=10, μ=2
8
| valid teams |
TFP 
| tasks |
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10
11
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