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31
Truth revelation in approximately efficient combinatorial auctions
 Journal of the ACM
, 2002
"... Abstract. Some important classical mechanisms considered in Microeconomics and Game Theory require the solution of a difficult optimization problem. This is true of mechanisms for combinatorial auctions, which have in recent years assumed practical importance, and in particular of the gold standard ..."
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Cited by 182 (1 self)
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Abstract. Some important classical mechanisms considered in Microeconomics and Game Theory require the solution of a difficult optimization problem. This is true of mechanisms for combinatorial auctions, which have in recent years assumed practical importance, and in particular of the gold standard for combinatorial auctions, the Generalized Vickrey Auction (GVA). Traditional analysis of these mechanisms—in particular, their truth revelation properties—assumes that the optimization problems are solved precisely. In reality, these optimization problems can usually be solved only in an approximate fashion. We investigate the impact on such mechanisms of replacing exact solutions by approximate ones. Specifically, we look at a particular greedy optimization method. We show that the GVA payment scheme does not provide for a truth revealing mechanism. We introduce another scheme that does guarantee truthfulness for a restricted class of players. We demonstrate the latter property by identifying natural properties for combinatorial auctions and showing that, for our restricted class of players, they imply that truthful strategies are dominant. Those properties have applicability beyond the specific auction studied.
Virtual Memory Primitives for User Programs
, 1991
"... Memory Management Units (MMUs) are traditionally used by operating systems to implement diskpaged virtual memory. Some operating systems allow user programs to specify the protection level (inaccessible, readonly. readwrite) of pages, and allow user programs t.o handle protection violations. bur. ..."
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Cited by 173 (2 self)
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Memory Management Units (MMUs) are traditionally used by operating systems to implement diskpaged virtual memory. Some operating systems allow user programs to specify the protection level (inaccessible, readonly. readwrite) of pages, and allow user programs t.o handle protection violations. bur. these mechanisms are not. always robust, efficient, or wellmat. ched to the needs of applications.
Truth Revelation in Rapid, Approximately Efficient Combinatorial Auctions
 In ACM Conference on Electronic Commerce (EC99
, 1999
"... Some important classical mechanisms considered in Microeconomics and Game Theory require the solution of a difficult optimization problem. This is true of mechanisms for combinatorial auctions, which have in recent years assumed practical importance, and in particular of the gold standard for co ..."
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Cited by 77 (5 self)
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Some important classical mechanisms considered in Microeconomics and Game Theory require the solution of a difficult optimization problem. This is true of mechanisms for combinatorial auctions, which have in recent years assumed practical importance, and in particular of the gold standard for combinatorial auctions, the Generalized Vickrey Auction (GVA). Traditional analysis of these mechanisms  in particular, their truth revelation properties  assumes that the optimization problems are solved precisely. In reality, these optimization problems can usually be solved only in an approximate fashion. We investigate the impact on such mechanisms of replacing exact solutions by approximate ones. Specifically, we look at a particular greedy optimization method, which has empirically been shown to perform well. We show that the GVA payment scheme does not provide for a truth revealing mechanism. We introduce another scheme that does guarantee truthfulness for a restricted class...
Combinatorial interpretations for ranktwo cluster algebras of affine type
 Electron. J. Combin
"... Fomin and Zelevinsky [6] show that a certain twoparameter family of rational recurrence relations, here called the (b, c) family, possesses the Laurentness property: for all b, c, each term of the (b, c) sequence can be expressed as a Laurent polynomial in the two initial terms. In the case where t ..."
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Cited by 17 (7 self)
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Fomin and Zelevinsky [6] show that a certain twoparameter family of rational recurrence relations, here called the (b, c) family, possesses the Laurentness property: for all b, c, each term of the (b, c) sequence can be expressed as a Laurent polynomial in the two initial terms. In the case where the positive integers b, c satisfy bc < 4, the recurrence is related to the root systems of finitedimensional rank 2 Lie algebras; when bc> 4, the recurrence is related to KacMoody rank 2 Lie algebras of general type [9]. Here we investigate the borderline cases bc = 4, corresponding to KacMoody Lie algebras of affine type. In these cases, we show that the Laurent polynomials arising from the recurence can be viewed as generating functions that enumerate the perfect matchings of certain graphs. By providing combinatorial interpretations of the individual coefficients of these Laurent polynomials, we establish their positivity. 1
On the Counting of Fully Packed Loop Configurations: Some new conjectures
, 2004
"... New conjectures are proposed on the numbers of FPL configurations pertaining to certain types of link patterns. Making use of the Razumov and Stroganov Ansatz, these conjectures are based on the analysis of the ground state of the TemperleyLieb chain, for periodic boundary conditions and socalled ..."
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Cited by 13 (1 self)
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New conjectures are proposed on the numbers of FPL configurations pertaining to certain types of link patterns. Making use of the Razumov and Stroganov Ansatz, these conjectures are based on the analysis of the ground state of the TemperleyLieb chain, for periodic boundary conditions and socalled "identified connectivities", up to size 2n = 22.
TwoDimensional Scaling Limits via Marked Nonsimple Loops
, 2006
"... We postulate the existence of a natural Poissonian marking of the double (touching) points of SLE6 and hence of the related continuum nonsimple loop process that describes macroscopic cluster boundaries in 2D critical percolation. We explain how these marked loops should yield continuum versions of ..."
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Cited by 12 (5 self)
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We postulate the existence of a natural Poissonian marking of the double (touching) points of SLE6 and hence of the related continuum nonsimple loop process that describes macroscopic cluster boundaries in 2D critical percolation. We explain how these marked loops should yield continuum versions of nearcritical percolation, dynamical percolation, minimal spanning trees and related plane filling curves, and invasion percolation. We show that this yields for some of the continuum objects a conformal covariance property that generalizes the conformal invariance of critical systems. It is an open problem to rigorously construct the continuum objects and to prove that they are indeed the scaling limits of the corresponding lattice objects.
Experiments in dilute atomic BoseEinstein condensation
 in BoseEinstein Condensation in Atomic Gases, Proc. International School Phys. ”Enrico Fermi”, Course CXL
, 1999
"... 1. 1. Why BEC?. – In the month we began writing this paper, fourteen papers on the explicit topic of BoseEinstein condensation (BEC) in a dilute gas appeared in the pages of Physical Review. Both theoretical and experimental activity in BEC has expanded dramatically in the three years since the fir ..."
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Cited by 4 (0 self)
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1. 1. Why BEC?. – In the month we began writing this paper, fourteen papers on the explicit topic of BoseEinstein condensation (BEC) in a dilute gas appeared in the pages of Physical Review. Both theoretical and experimental activity in BEC has expanded dramatically in the three years since the first observation of BEC in a dilute atomic gas.
Effects of Random Density Fluctuations on MatterEnhanced Neutrino Flavor Transitions in Supernovae and Implications for Supernova Dynamics and Nucleosynthesis
, 1995
"... We calculate the effects of random density fluctuations on twoneutrino flavor transformations (ν τ(µ) ⇀ ↽ νe) in the postcorebounce supernova environment. In particular, we follow numerically the flavor evolution of neutrino states propagating through a stochastic field of density fluctuations. We ..."
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Cited by 3 (0 self)
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We calculate the effects of random density fluctuations on twoneutrino flavor transformations (ν τ(µ) ⇀ ↽ νe) in the postcorebounce supernova environment. In particular, we follow numerically the flavor evolution of neutrino states propagating through a stochastic field of density fluctuations. We examine the approach to neutrino flavor depolarization, and study the effects of this phenomenon in both the early shock reheating epoch and the later rprocess nucleosynthesis epoch. Our results suggest that significant fluctuationinduced neutrino flavor depolarization effects occur in these environments only when the zeroorder (without density fluctautions) evolution of the neutrino states includes adiabatic propagation through resonances (mass level crossings). In the shock reheating epoch, depolarization effects from fluctuations with amplitudes larger than 0.05 % of the local matter density can cause an increase in the heating rate of the
Studies on susceptibility to infection following ionizing radiation. Pathogenesis of endogenous bacteriemia
, 1955
"... Two questions arose in the course of a study of the fatal bacteremias which occur in mice following their exposure to moderate doses of total body xirradiation: Why is the onset of bacteremia delayed for so long after irradiation? And by what route do the causative microorganisms gain entrance to t ..."
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Cited by 3 (0 self)
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Two questions arose in the course of a study of the fatal bacteremias which occur in mice following their exposure to moderate doses of total body xirradiation: Why is the onset of bacteremia delayed for so long after irradiation? And by what route do the causative microorganisms gain entrance to the blood stream? Since the bacteremias are always caused by members of the mouse's enteric flora (1, 2), the reservoir from which they originate is presumed to be the lumen of the gut. The primary barrier against bacterial invasion from the intestinal tract, its mucosal lining, is known to be especially sensitive to xirradiation. But the microscopic evidence of injury to the mucosa resulting from the doses used (500 to 700 r) has been reported (38) to be maximal within a few hours and to have been repaired by the 4th or 5th day. Not until this time, the latter part of the first week post irradiation, do the bacteremias begin to occur. In other words, the period of maximal damage to the intestinal mucosa does not correlate in time with the period of highest incidence of bacteremia caused by microorganisms of intestinal