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The Game Inside the Game. Karl Lieberherr based on Master Thesis of Anna Hoepli at ETH Zurich in 2007 (communicated by Emo Welzl). SDG Partial Satisfaction Game Theoretic View. 2 person game, Bob and Alice. Unsatisfiable CSP Formula F is the “board” of the game. Bob chooses a constraint C.
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The Game Inside the Game Karl Lieberherr based on Master Thesis of Anna Hoepli at ETH Zurich in 2007 (communicated by Emo Welzl)
SDG Partial SatisfactionGame Theoretic View • 2 person game, Bob and Alice. Unsatisfiable CSP Formula F is the “board” of the game. • Bob chooses a constraint C. • Alice chooses an assignment A. • If A satisfies C, Alice wins; otherwise Bob.
Traditional Game • F must be unsatisfiable, otherwise Bob would not have a chance if Alice knows a satisfying assignment. • The unsatisfiable constraint is not allowed to be in F. (Relation 0). • Both play simultaneously. • We play with symmetric formulas.
T = {(1,1) (2,0)} • Two constraint types: 1. A / 2. !A or !B • Assume F is symmetric. • Bob chooses a constraint of type 1 with prob. m1 and a constraint of type 2 with probability m2=1-m1.
Game matrix sik for symmetric F variables set 1 relation R b(n,k) = binomial(n,k)
Game matrix sik for symmetric F:General Case variables set 1 relation R b(n,k) = binomial(n,k)
General Formula • http://www.ccs.neu.edu/research/demeter/papers/evergreen/cp07-submission.pdf • page 6
Linear program (Alice maximizes t) • max t (t = satisfaction ratio) • s10*l0+s11*l1+ … +s1n*ln≥ t • s20*l0+s21*l1+ … +s2n*ln≥ t • l0+l1+ … +ln= 1 • li≥ 0 for all i in [0,1, … ,n]
Linear program (Alice maximizes t) • max t (t = satisfaction ratio) • -s10*l0-s11*l1- … -s1n*ln+t ≤ 0 • -s20*l0-s21*l1- … -s2n*ln+t ≤ 0 • l0+l1+ … +ln= 1 • li≥ 0 for all i in [0,1, … ,n]
Dual linear program(Bob minimizes t) • min t (t = satisfaction ratio) • s10*m1+s20*m2≤ t • s11*m1+s21*m2≤ t • … • s1n*m1+s2n*m2≤ t • m1+m2= 1 • mi≥ 0 for all i in [1,2]
Mechanical way of finding best price and worst raw material • Given derivative d = ((R1, … ), p?,seller) • Choose n, e.g. n = 20. • Generate matrix sik. It has one row per relation and n columns. • Create input to LP solver using dual program, because we need the the mi for the raw materials. The minimum is the break-even price.
SDG classic tpred = lim n -> ∞ min all raw materials rm of size n satisfying predicate pred max all finished products fp produced for rm q(fp) Seller approximates minimum efficiently Buyer approximates Max efficiently
Spec for RM and FP tpred = lim n -> ∞ min all raw materials rm of size n satisfying predicate pred and having property WORST(rm) max small subset of all finished products fp produced for rm q(fp)