Memory Management Units (MMUs) are traditionally used by operating systems to implement disk-paged virtual memory. Some operating systems allow user programs to specify the protection level (inaccessible, readonly. read-write) of pages, and allow user programs t.o handle protection violations. bur. these mechanisms are not. always robust, efficient, or well-mat. ched to the needs of applications.

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.

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...

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 Temperley-Lieb chain, for periodic boundary conditions and so-called "identified connectivities", up to size 2n = 22.

Fomin and Zelevinsky [6] show that a certain two-parameter 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 finite-dimensional rank 2 Lie algebras; when bc> 4, the recurrence is related to Kac-Moody rank 2 Lie algebras of general type [9]. Here we investigate the borderline cases bc = 4, corresponding to Kac-Moody 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

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 near-critical 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.

Contents 0 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 I Endomorphism rings and character tables 6 1 Endomorphisms of monomial representations . . . . . . . . . . . . . . 6 2 Fitting correspondence . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 3 Characters of endomorphism rings . . . . . . . . . . . . . . . . . . . . 17 4 Krein parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 5 Coverings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 6 Condensation functors . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 7 Orbital graphs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 II Computational techniques 58 8 Intersection numbers and character tables . . . . . . . . . . . . . . . . 58 9 Condensation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67 10 Enumeration of long orbits . . . . . . . . . . . . . . . . . . . . . . . . 73 III Explicit results 79 1

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 x-irradiation: 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 x-irradiation. But the microscopic evidence of injury to the mucosa resulting from the doses used (500 to 700 r) has been reported (3-8) 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

Abstract not found

The reaction e + e \Gamma ! flfl is an ideal process to test QED in e + e \Gamma collisions, since it does not receive tree level contribution from the exchange of weak bosons. It can thus be used to set limits on the energy scale of new interactions. In this note we review two technical aspects related to the study of the e + e \Gamma ! flfl reaction: the definition of the scattering angle, which is affected by the presence of radiative corrections, and the methods used to set limits on the energy scale of new interactions. We also show an application of these methods to the LEP 1 dataset. 1 Introduction The reaction e + e \Gamma ! flfl is an ideal process to test QED in e + e \Gamma collisions, since it does not receive tree level contributions from the exchange of weak bosons. In the framework of the Standard Model this reaction can only proceed through the exchange of a virtual electron, the decay of a massive spin 1 particle (the Z 0 ) into two photon...