Game Authority for Robust and Scalable Distributed Selfish-Computer Systems
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Transcript of Game Authority for Robust and Scalable Distributed Selfish-Computer Systems
Game Authority for Robust and Scalable
Distributed Selfish-Computer Systems
Shlomi Dolev, BGU (Israel)Elad M. Schiller, Chalmers
(Sweden)Paul G. Spirakis, CTI (Greece)
Philippas Tsigas, Chalmers (Sweden)
The system designer
Distributed computing assumes identical programs.
How to design distributed algorithms for the wild
internet?
Let’s play the prisoner dilemma game.
Use game theory for selfish-computer systems.
The system designer
BA Silent Betray
Silent
Betray
(+1,
+1)
(+3,
–1)
(–1,
+3)
( 0, 0
)
John Nash
Game theory predicts: selfish-computer choose
betray!
Yes, I trust game theory.OK... Let’s play
in a real system.
The system designer
We need a distributed game authority.
O.K., we should explicitly enforce the implicit rules of the game.
In a real system, where I am the only
authority…
they would be free to escape!
The Society Moral Code
• Complete anarchy exists without moral codes• Game authority founded over the moral majority
– choose and enforces the rules of the game– promote freedom of choice for the society’s benefit
• We promote honestly selfish behavior for the sake of:• end-point creativity• motivation for success
The Society Moral Code
• Complete anarchy exists without moral codes• Game authority founded over the moral majority
– choose and enforces the rules of the game– promote freedom of choice for the society’s benefit
Benefits • End-point success
• that yields global success
• Provable scalability• from the days of
Greece • Provable robustness, still
Technical Contributions
Cost Reduction: • We replace the higher price of anarchy
with the lower price of stability!
Technical Contributions
Cost Reduction: • We replace the higher price of anarchy
with the lower price of stability!
Price of anarchy (PoA) • Worst case ratio
between:
NE’s social cost, and
the social optimum
Koutsoupias & Papadimitriou STACS’99
Social optimum
Worst NE
PoA
Good Bad
Technical Contributions
Social optimum Best NE
PoS
Good Bad
Price of stability (PoS)• Best case ratio between:
NE’s social cost, and
the social optimum
Anshelevich et al. FOCS'04
Worst NE
PoA
Cost Reduction: • We replace the higher price of anarchy
with the lower price of stability!
Game Authority Implementation
• Can we assume that all components are selfish?– impossible: Phy. layer game & Mac layer game &, … ,
& possible failures & imprecise utility • how to bound the PoA?
Social optimum Best NE
PoS
Good Bad
• Honest and moral based middleware tolerating • Byzantine faults• transient faults
• Facilitates interaction among honestly selfish agents
Worst NE
PoA Explicit
∞
Moral Code
Middleware: Game Authority
Application-layer:
Honestly selfish agents (majority)
Implementation (cont.)
• Byzantine agreement • Cryptographic primitives• Game theory analysis
• How to decide on the preferable game? • How does the honest majority audit the game?• How to preserve privacy in simultaneous plays?
Your attention is appreciated
More details:Technical report number TR-2006:9Computer Science and Engineering Chalmers University of technology, 2006Also, technical report, DELIS, 2006. Accessible via http://delis.upb.de/docs/
Rabbi Akiva said: All is foreseen, but freedom of choice is given. The world is judged in goodness, yet all is proportioned to one's work. (Mishnah Pirkei Avot, Chapter 3, 19)
הכול צפוי, והרשות נתונה; ובטוב העולם נידון. והכול פרקי (. לפי רוב המעשה, אבל לא על פי המעשה
אבות, ג` ט"ו)