Cost-Sharing Games v s - t 200 100 150 75 100 50 50 25 0 - - PowerPoint PPT Presentation

Cost-Sharing Games

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s v u t

50 100 150 200 1 2 3 4 4 8 12 16 1 2 3 4 25 50 75 100 1 2 3 4 25 50 75 100 1 2 3 4 4 8 12 16 1 2 3 4

u - t s - t

s - t

Cost-Sharing Games

• Total cost of an outcome of the game = Sum of the costs of the edges.
• Players’ decisions depend on the protocol.
• Selfish behavior of the players might lead in to inefficient equilibria.
• Our goal is to design protocols in which while players only think about their own

cost-share, the equilibrium still has low social cost (i.e. Low PoA)

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Cost-Sharing Games

• What does the protocol know in defining the cost share of player in edge
• Oblivious: Just the set of players using
• Omniscient: Everything about the game
• Resource-aware: Everything about

and set of the players using

i e e G e

Informational Power

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How to use this extra information ?

Results

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Concave Convex

Series-Parallel Graphs


(symmetric)

Directed Acyclic Graphs


(symmetric)

Multicast

PoA = 2 + ε n > 1 → PoA = 1 + ε

PoA = 1

→ PoA = Ω(n)

→ PoA = Ω( n)

Budget Balance Overcharging

PoA = 1

→ PoA = Ω(n)

→ PoA > 1.18

Budget Balance Overcharging

Incremental protocol [Moulin ’99] Generalization of the protocol for parallel links [Christodoulou et al. ’17] With overcharging