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Methods for Coalition Formation in Adaptation-Based Social
NetworksLevi Barton, Vicki H. Allan
Utah State University
Overview
• Optimal Coalitions
• Dynamic Environment
• Agent Organized Network
• Agent Types
• Results
• Conclusions
• Questions
Optimal Coalition Formation
• Requires Complete Information
• Substantial Computation Time
• May Not Be Feasible
Dynamic Environment
• Incomplete Information– Limited Sensor Capabilities– Damaged Sensors– Communication Failures
Dynamic Environment
• Agents– Limited View of Environment– Discovery of Environment
• Tasks– Periodic Creation– Decreasing Value– Time Sensitive
Agent Organized Network
• Agents in Charge– Choose Neighbors– Choose Tasks
Agent Organized Network
• Network Arcs– Physical Distance– Limited Communication– Trust– Potential Team Members
Agent Organized Network
• Initial Network Arcs– Random Agent Locations– Distance Between Agents d– Arcs Added When d < 100
Agent Organized Network
• Tasks– Require Specific Skills– Specified by Array skillCount[1,…,skillMax]
Agent Organized Network
• Agents Paired to Tasks in Teams– Agent Team Connected in Network– Teams Formed Using Set of Friends of a
Friend (FOAF)– FOAF Agent Set of Preferred Neighbors
Agent Organized Network
• Agent Skills– One Skill Per Agent
• Neighborhood Skills– Skills Possessed by Neighbors and
Neighbor’s Neighbors (FOAF)
Agent Organized Network
• Agent Flow of Control
Uncommitted
Committed
Failure
Success
Active
Success
Failure
Join ProposeRewire Idle
Failure
Rewiring Strategies
• Performance– Rewire Based on Performance Estimate
• Structural– Rewire Based on Network Structure
• Diversity– Rewire Based on Skill Diversity
Task Selection
• Basic– Select First Available Task
• Strategic– Select Best Available Task (If Ratio of Skills
Needed in Task and Skills Available in Neighborhood is > 0.34)
Task Patience
• Patient– Remain Committed To Task Until Task Either
Succeeds or Fails
• Impatient– Abandon Task if Number of Uncommitted
Agents in Neighborhood is < Number of Skills Unfilled in Task
Agent Types
Agent Types
• Four Categories– Basic Task Selection and Task Patience– Basic Task Selection and Task Impatience– Strategic Task Selection and Task Patience– Strategic Task Selection and Task Impatience
0
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0.6
0 500 1000 1500 2000
perf
orm
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time
AON Performance No Adaptation
Performance agentStructural agent
StructuralStrat agentDiversityStratImpatient agent
DiversityImpatient agentStructuralStratImpatient agent
No Adaptation
Basic + Patient
Strategic + Patient
Basic + Impatient
Strategic + Impatient
0
0.1
0.2
0.3
0.4
0.5
0.6
0 500 1000 1500 2000
perf
orm
an
ce
time
AON Performance No Adaptation
Performance agentStructural agent
StructuralStrat agentDiversityStratImpatient agent
DiversityImpatient agentStructuralStratImpatient agent
No Adaptation
0
0.05
0.1
0.15
0.2
0.25
0.3
0 500 1000 1500 2000
perf
orm
an
ce
time
AON Performance
Performance agent (DegreeLimit = 5)Performance agent (DegreeLimit = 10)Performance agent (DegreeLimit = 20)
Performance Agents
0
0.1
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0 500 1000 1500 2000
perf
orm
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ce
time
AON Performance
Structural agent (DegreeLimit = 5)Structural agent (DegreeLimit = 10)Structural agent (DegreeLimit = 20)
Structural Agents
0
0.1
0.2
0.3
0.4
0.5
0 500 1000 1500 2000
perf
orm
an
ce
time
AON Performance (MaxTimeCommitted = 4)
Performance agentStructural agent
StructuralStrat agentDiversityStratImpatient agent
DiversityImpatient agentStructuralStratImpatient agent
Maximum Committed Four Time Steps
Maximum Committed Ten Time Steps
0
0.1
0.2
0.3
0.4
0.5
0 500 1000 1500 2000
perf
orm
an
ce
time
AON Performance (MaxTimeCommitted = 10)
Performance agentStructural agent
StructuralStrat agentDiversityStratImpatient agent
DiversityImpatient agentStructuralStratImpatient agent
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0.16
0 500 1000 1500 2000
perf
orm
an
ce
time
AON Performance (GenInterval = 0.5)
Performance agentStructural agent
StructuralStrat agentDiversityStratImpatient agent
DiversityImpatient agentStructuralStratImpatient agent
Two Tasks Per Time Step
0
0.02
0.04
0.06
0.08
0.1
0 500 1000 1500 2000
perf
orm
an
ce
time
AON Performance (GenInterval = 0.25)
Performance agentStructural agent
StructuralStrat agentDiversityStratImpatient agent
DiversityImpatient agentStructuralStratImpatient agent
Four Tasks Per Time Step
Degree Limit of Five
0
0.1
0.2
0.3
0.4
0.5
0.6
0 500 1000 1500 2000
perf
orm
an
ce
time
AON Performance (DegreeLimit = 5)
Performance agentStructural agent
StructuralStrat agentDiversityStratImpatient agent
DiversityImpatient agentStructuralStratImpatient agent
Degree Limit of Ten
0
0.1
0.2
0.3
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0.5
0.6
0.7
0.8
0 500 1000 1500 2000
perf
orm
an
ce
time
AON Performance (DegreeLimit = 10)
Performance agentStructural agent
StructuralStrat agentDiversityStratImpatient agent
DiversityImpatient agentStructuralStratImpatient agent
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0 500 1000 1500 2000
perf
orm
an
ce
time
AON Performance (DegreeLimit = 20)
Performance agentStructural agent
StructuralStrat agentDiversityStratImpatient agent
DiversityImpatient agentStructuralStratImpatient agent
Degree Limit of Twenty
Average Density Degree Limit of Five
0
10
20
30
40
50
60
70
0 500 1000 1500 2000
avera
ge d
en
sity
time
AON Average Density (DegreeLimit = 5)
Performance agentStructural agent
StructuralStrat agentDiversityStratImpatient agent
DiversityImpatient agentStructuralStratImpatient agent
Average Density Degree Limit of Ten
0
10
20
30
40
50
60
70
0 500 1000 1500 2000
avera
ge d
en
sity
time
AON Average Density (DegreeLimit = 10)
Performance agentStructural agent
StructuralStrat agentDiversityStratImpatient agent
DiversityImpatient agentStructuralStratImpatient agent
0
10
20
30
40
50
60
70
0 500 1000 1500 2000
avera
ge d
en
sit
y
time
AON Average Density (DegreeLimit = 20)
Performance agentStructural agent
StructuralStrat agentDiversityStratImpatient agent
DiversityImpatient agentStructuralStratImpatient agent
Average Density Degree Limit of Twenty
Conclusions
• Best Agent Type– StructuralStratImpatient Agent
• Impatience Under High Task Load
• Strategic Under High Task Load
• Degree Limit Feasible
Questions?
