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There are infinite sequences of graphs { G} where | G| = n such that the minimal dominating sets for G × H fall into predictable patterns, in light of which γ ( G × H) may be nearly linear in n; the coefficient of linearity may be regarded as the average density of the dominating set in the H-fibers of the product. The specific cases where the sequence { G} consists of cycles or path is explored in detail, and the domination density of the Grötzsch graph is calculated. For several other sequences { G}, the limit of this density can be seen to exist; in other cases the ratio $${\frac{\gamma (G_n \times H)}{\gamma (G_n)}}$$ proves to be of greater interest, and also exists for several families of graphs. [ABSTRACT FROM AUTHOR]

Abstract: We present a slight variation on a notion of weak -groupoid introduced by Grothendieck in Pursuing Stacks and we study the homotopy theory of these -groupoids. We prove that the obvious definition for homotopy groups of Grothendieck -groupoids does not depend on any choice. This allows us to give equivalent characterizations of weak equivalences of Grothendieck -groupoids, generalizing a well-known result for strict -groupoids. On the other hand, given a model category  in which every object is fibrant, we construct, following Grothendieck, a fundamental -groupoid functor from to the category of Grothendieck -groupoids. We show that if is an object of , then the homotopy groups of  and of are canonically isomorphic. We deduce that the functor respects weak equivalences. [Copyright &y& Elsevier]

This short note considers the Białynicki-Birula decomposition of Deligne-Mumford stacks under one-dimensional torus actions and extends a result of Oprea. [ABSTRACT FROM AUTHOR]

Let $GO(2n)$ be the general orthogonal group (the group of similitudes) over any algebraically closed field of characteristic $\ne 2$. We determine the smooth-étale cohomology ring with $\mathbb F_2$ coefficients of the algebraic stack $BGO(2n)$. In the topological category, Holla and Nitsure determined the singular cohomology ring of the classifying space $BGO(2n)$ of the complex Lie group $GO(2n)$ in terms of explicit generators and relations. We extend their results to the algebraic category. The chief ingredients in this are: (i) an extension to étale cohomology of an idea of Totaro, originally used in the context of Chow groups, which allows us to approximate the classifying stack by quasi projective schemes; and (ii) construction of a Gysin sequence for the ${\mathbb G_m}$-fibration $BO(2n)\to BGO(2n)$ of algebraic stacks. [ABSTRACT FROM AUTHOR]

Abstract: We formulate a notion of “geometric reductivity” in an abstract categorical setting which we refer to as adequacy. The main theorem states that the adequacy condition implies that the ring of invariants is finitely generated. This result applies to the category of modules over a bialgebra, the category of comodules over a bialgebra, and the category of quasi-coherent sheaves on an algebraic stack of finite type over an affine base. [Copyright &y& Elsevier]

Abstract: Let S be a site. We introduce the 2-category of biextensions of strictly commutative Picard S-stacks. We define the pull-back, the push-down, and the sum of such biextensions and we compute their homological interpretation: if and are strictly commutative Picard S-stacks, the equivalence classes of biextensions of by are parametrized by the cohomology group , the isomorphism classes of arrows from such a biextension to itself are parametrized by the cohomology group and the automorphisms of an arrow from such a biextension to itself are parametrized by the cohomology group , where and are the complexes associated to and respectively. [Copyright &y& Elsevier]

We present a construction of Donaldson-Thomas invariants for three-dimensional projective Calabi-Yau Deligne-Mumford stacks. We also study the structure of these invariants for 'etale gerbes over such stacks. [ABSTRACT FROM AUTHOR]

We compute étale cohomology groups $$H_{\acute{\mathrm{e}}\mathrm{t}}^r(X, \mathbb G _m)$$ in several cases, where $$X$$ is a connected smooth tame Deligne-Mumford stack of dimension $$1$$ over an algebraically closed field. We have complete results for orbicurves (and, more generally, for twisted nodal curves) and in the case all stabilizers are cyclic; we give partial results and examples in the general case. In particular, we show that if the stabilizers are abelian then $$H_{\acute{\mathrm{e}}\mathrm{t}}^2(X, \mathbb{G }_m)$$ does not depend on $$X$$ but only on the underlying orbicurve $$Y$$ and on the generic stabilizer. We show with two examples that, in general, the higher cohomology groups $$H_{\acute{\mathrm{e}}\mathrm{t}}^r(X, \mathbb{G }_m)$$ cannot be computed knowing only the base of the gerbe $$X \rightarrow Y$$ and the banding group. [ABSTRACT FROM AUTHOR]

Abstract: In the theory of the moduli-stacks of stable -pointed curves, there are two fundamental functors, contraction and stabilization. These functors are constructed in Knudsen (1983) , where they are used to show that the various ’s are DM-stacks. In the treatment of stabilization, there is a claim stated about the deformations of a pointed ordinary double point. This claim is not proved in Knudsen (1983) . The goal of this paper is to prove this claim. We decided not to use descent, so the equations are less simple than in Knudsen (1983) , but the treatment is more elementary and the results seemingly more general. [Copyright &y& Elsevier]

In this paper, we compare the virtual fundamental classes of the stacks of (g, β, μ)-stable ramified maps ,Ug, μ(X, β) and of (g, β, μ)-log stable ramified maps Ulog g,μ(X, β). For that we will see how they are identified via virtual normalization and then apply Costello's push-forward formula. [ABSTRACT FROM AUTHOR]

Abstract: We describe the first implementation of multi-prompt delimited control operators in OCaml that is direct in that it captures only the needed part of the control stack. The implementation is a library that requires no changes to the OCaml compiler or run-time, so it is perfectly compatible with existing OCaml source and binary code. The library has been in fruitful practical use since 2006. We present the library as an implementation of an abstract machine derived by elaborating the definitional machine. The abstract view lets us distill a minimalistic API, scAPI, sufficient for implementing multi-prompt delimited control. We argue that a language system that supports exception and stack-overflow handling supports scAPI. With byte- and native-code OCaml systems as two examples, our library illustrates how to use scAPI to implement multi-prompt delimited control in a typed language. The approach is general and has been used to add multi-prompt delimited control to other existing language systems. [Copyright &y& Elsevier]

Abstract: In the paper of Bonora et al. (2008) we have shown, in the context of type II superstring theory, the classification of the allowed B-field and A-field configurations in the presence of anomaly-free D-branes, the mathematical framework being provided by the geometry of gerbes. Here we complete the discussion considering in detail the case of a stack of D-branes, carrying a non-abelian gauge theory, which was just sketched in Bonora et al. (2008) . In this case we have to mix the geometry of abelian gerbes, describing the B-field, with the one of higher-rank bundles, ordinary or twisted. We describe in detail the various cases that arise according to such a classification, as we did for a single D-brane, showing under which hypotheses the A-field turns out to be a connection on a canonical gauge bundle. We also generalize to the non-abelian setting the discussion about “gauge bundles with non-integral Chern classes”, relating them to twisted bundles with connection. Finally, we analyze the geometrical nature of the Wilson loop for each kind of gauge theory on a D-brane or stack of D-branes. [Copyright &y& Elsevier]

Abstract: A convenient bicategory of topological stacks is constructed which is both complete and Cartesian closed. This bicategory, called the bicategory of compactly generated stacks, is the analogue of classical topological stacks, but for a different Grothendieck topology. In fact, there is an equivalence of bicategories between compactly generated stacks and those classical topological stacks which admit locally compact Hausdorff atlases. Compactly generated stacks are also equivalent to a bicategory of topological groupoids and principal bundles, just as in the classical case. If a classical topological stack and a compactly generated stack have a presentation by the same topological groupoid, then they restrict to the same stack over locally compact Hausdorff spaces and are homotopy equivalent. [Copyright &y& Elsevier]

Regular model checking is a generic technique for verification of infinite-state and/or parametrised systems which uses finite word automata or finite tree automata to finitely represent potentially infinite sets of reachable configurations of the systems being verified. The problems addressed by regular model checking are typically undecidable. In order to facilitate termination in as many cases as possible, acceleration is needed in the incremental computation of the set of reachable configurations in regular model checking. In this work, we describe how various incrementally refinable abstractions on finite (word and tree) automata can be used for this purpose. Moreover, the use of abstraction does not only increase chances of the technique to terminate, but it also significantly reduces the problem of an explosion in the number of states of the automata that are generated by regular model checking. We illustrate the efficiency of abstract regular (tree) model checking in verification of simple systems with various sources of infinity such as unbounded counters, queues, stacks, and parameters. We then show how abstract regular tree model checking can be used for verification of programs manipulating tree-like dynamic data structures. Even more complex data structures can be handled using a suitable tree-like encoding. [ABSTRACT FROM AUTHOR]

Abstract: We prove some finiteness theorems for the Picard functor of an algebraic stack, in the spirit of SGA 6, exp. XII and XIII. In particular, we give a stacky version of Raynaudʼs relative representability theorem, we give sufficient conditions for the existence of the torsion component of the Picard functor, and for the finite generation of the Néron–Severi groups or of the Picard group itself. We give some examples and applications. In Appendix A, we prove the semicontinuity theorem for a (non-necessarily tame) algebraic stack. [Copyright &y& Elsevier]

One of the key challenges in 3D Stacked-ICs (3D-SIC) is to guarantee high product quality at minimal cost. Quality is mostly determined by the applied tests and cost trade-offs. Testing 3D-SICs is very challenging due to several additional test moments for the mid-bond stacks, i.e., partially created stacks. The key question that this paper answers is what is the best test flow to be used in order to optimize the overall cost while realizing the required quality? We first present a framework covering different test flows for 3D Die-to-Wafer (D2W) stacked ICs. Thereafter, we present a cost model that allows us to evaluate these test flows. The impact of different test flows on the overall 3D-SIC cost for several die yields and stack sizes are investigated; a breakdown of the cost into test, manufacturing and packaging cost is also provided. Our simulation results show that both the test cost and the overall cost in D2W stacking strongly depends on the selected test flow; test flows with pre-bond and mid-bond stacking tests (performed during the stacking process) show a higher test cost share, but significantly reduce the overall 3D-SIC cost. [ABSTRACT FROM AUTHOR]

The article discusses the continuous analogue of stacking identical bricks in constructing a tower of maximal overhang. It states that the overhang can be arranged to be as large as desired since the harmonic series diverges by using a large number of blocks. It says that the harmonic staircases and all stacks in the interest are simply figures in the xy-plane which are orthogonally extended in the z-direction.

Abstract: We give an introduction to Joyceʼs construction of the motivic Hall algebra of coherent sheaves on a variety M. When M is a Calabi–Yau threefold we define a semi-classical integration map from a Poisson subalgebra of this Hall algebra to the ring of functions on a symplectic torus. This material will be used in Bridgeland (2011) to prove some basic properties of Donaldson–Thomas curve-counting invariants on Calabi–Yau threefolds. [Copyright &y& Elsevier]

In this paper we consider questions of the following type. Let k be a base field and K/k be a field extension. Given a geometric object X over a field K (e.g. a smooth curve of genus g) what is the least transcendence degree of a field of definition of X over the base field k? In other words, how many independent parameters are needed to define X? To study these questions we introduce a notion of essential dimension for an algebraic stack. Using the resulting theory, we give a complete answer to the question above when the geometric objects X are smooth, stable or hyperelliptic curves. The appendix, written by Najmuddin Fakhruddin, answers this question in the case of abelian varieties. [ABSTRACT FROM AUTHOR]

We prove two flat descent results in the setting of Artin n-stacks. First of all, a stack for the etale topology which is an Artin n-stack (in the sense of Simpson and Toën–Vezzosi) is also a stack for the flat (fppf) topology. Moreover, an n-stack, for the fppf topology, which admits a flat (fppf) n-atlas is an Artin n-stack (i.e. possesses a smooth n-atlas). We deduce from these two results a comparison between etale and fppf cohomologies (with coefficients in non-smooth group schemes and also non-abelian). This work is written in the setting of the derived stacks of Toën and Vezzosi, and all of these results are therefore also valid for derived Artin n-stacks. [ABSTRACT FROM AUTHOR]

Abstract: We show that the pushout of an étale morphism and an open immersion exists in the category of algebraic stacks and show that such pushouts behave similarly to the gluing of two open substacks. For example, quasi-coherent sheaves on the pushout can be described by a simple gluing procedure. We then outline a powerful dévissage method for representable étale morphisms using such pushouts. We also give a variant of the dévissage method for representable quasi-finite flat morphisms. [Copyright &y& Elsevier]

Abstract: Let S be a site. We introduce the notion of extensions of strictly commutative Picard S-stacks. We define the pull-back, the push-down, and the sum of such extensions and we compute their homological interpretation: if and are two strictly commutative Picard S-stacks, the equivalence classes of extensions of by are parametrized by the cohomology group , where and are the complex associated to and respectively. [Copyright &y& Elsevier]

Abstract: We study stacks of slope-semistable twisted sheaves on orbisurfaces with projective coarse spaces and prove that in certain cases they have many of the asymptotic properties enjoyed by the moduli of slope-semistable sheaves on smooth projective surfaces. [Copyright &y& Elsevier]

Abstract: We are given a stack of pancakes of different sizes and the only allowed operation is to take several pancakes from the top and flip them. The unburnt version requires the pancakes to be sorted by their sizes at the end, while in the burnt version they additionally need to be oriented burnt-side down. We are interested in the largest value of the number of flips needed to sort a stack of pancakes, both in the unburnt version () and in the burnt version (). We present exact values of up to and of up to and disprove a conjecture of Cohen and Blum by showing that the burnt stack is not the hardest to sort for . We also show that sorting a random stack of unburnt pancakes can be done with at most flips on average. The average number of flips of the optimal algorithm for sorting stacks of burnt pancakes is shown to be between and and we conjecture that it is . Finally we show that sorting the stack needs at least flips, which slightly increases the lower bound on . This bound together with the upper bound for sorting found by Heydari and Sudborough in 1997  gives the exact number of flips to sort it for and . [ABSTRACT FROM AUTHOR]

Abstract: This paper investigates vortex shedding processes occurring at the end of a stack of parallel plates, due to an oscillating flow induced by an acoustic standing wave. Here the hot-wire anemometry measurement technique is applied to detect the velocity fluctuations due to vortex shedding near the end of the stack. The hot-wire fast time response enables detailed frequency spectra of the velocity signal to be obtained, which can be used for identifying the dominant frequencies associated with vortex shedding, and thus allow calculation of the corresponding Strouhal numbers. By varying the stack configuration (the plate thickness and spacing) and the acoustic excitation level (the so-called drive ratio), the impact of the stack blockage ratio and the Reynolds number on the Strouhal number has been studied in detail. Furthermore, in the range of Reynolds numbers between 200 and 5000 a correlation between the Strouhal number and Reynolds number has been obtained and compared with analogous relationships in the steady flow. Particle Image Velocimetry (PIV) is also used to visualize the vortex shedding processes within an acoustic cycle, phase-by-phase, in particular during the part of the cycle when the fluid flows out of the stack—selected cases are shown for comparisons with hot-wire measurements. [Copyright &y& Elsevier]

Abstract: In this paper we consider deformations of an algebroid stack on an étale groupoid. We construct a differential graded Lie algebra (DGLA) which controls this deformation theory. In the case when the algebroid is a twisted form of functions we show that this DGLA is quasiisomorphic to the twist of the DGLA of Hochschild cochains on the algebra of functions on the groupoid by the characteristic class of the corresponding gerbe. [ABSTRACT FROM AUTHOR]

Abstract: A membraneless microfluidic fuel cell stack architecture is presented that reuses reactants from one cell to a subsequent one, analogous to PEMFC stacks. On-chip reactant reuse improves fuel utilization and power densities relative to single cells. The reactants flow separately through porous electrodes and interface with a non-reacting and conductive electrolyte which maintains their separation. The reactants remain separated downstream of the interface and are used in subsequent downstream cells. This fuel cell uses porous carbon for electrocatalysts and vanadium redox species as reactants with a sulfuric acid supporting electrolyte. The overall power density of the fuel cell increases with reactant flow rate and decreasing the separating electrolyte flow rate. The peak power, maximum fuel utilization, and efficiency nearly double when electrically connecting the cells in parallel. [ABSTRACT FROM AUTHOR]

Abstract: Herein, three-dimensional optical metamaterials consisting of metal-dielectric stacks are fabricated using a bottom-up approach. In this method, silver dendritic nanostructure was prepared as “meta-atom”, and then stacked up multilayered structure with dielectric films. Morphology of the metamaterials was examined by scanning electron microscopy. These bulk metamaterials exhibit pass-bands at optical frequencies and the slab focusing experiment reveals a clear point image. From a practical point of view, our findings point to a simpler avenue to fabricate thick, low-loss metamaterials. [Copyright &y& Elsevier]

Abstract: In this paper we give a construction of algebraic (Artin) stacks endowed with a modular map onto the moduli stack of stable curves of genus g with n marked points. The stacks we construct are smooth, irreducible and have dimension , yielding a geometrically meaningful compactification of the universal Picard stack parametrizing n-pointed smooth curves together with a line bundle. [ABSTRACT FROM AUTHOR]

Abstract: Processor Allocator (PA) is a crucial factor in modern Chip MultiProcessors (CMPs). A modern CMP uses Network on Chip (NoC) as communication technique between cores. Thus, the topology of the implemented NoC has also significant impact on the CMP’s performance. A good processor allocation technique needs to be fast and ensure the highest possible system utilization. In this paper, we propose a processor allocation technique for such an efficient and fast PA. The PA is driven by a Bit Map Allocation for Torus (BMAT) algorithm, which is a technique designed for k-ary 2-cube topology. The proposed BMAT scheme is presented and described along with a new Busy List Allocation for Torus (BLAT), Sorting Allocation for Torus (SAT) and Stack Based Allocation for Torus (SBAT) algorithms. The presented techniques are compared with previously known important schemes for k-ary 2-mesh topology. The research ideas have been verified using experiments that have also been described in the paper. The presented simulation results reveal that the proposed processor allocation algorithm for k-ary 2-cube, as a technique for PA, achieves better allocation time than all other existing algorithms while the CMP with such a PA is characterized by very high system utilization. [ABSTRACT FROM AUTHOR]

We give a geometric definition of smooth toric Deligne-Mumford stacks using the action of a ''torus''. We show that our definition is equivalent to the one of Borisov, Chen and Smith in terms of stacky fans. In particular, we give a geometric interpretation of the combinatorial data contained in a stacky fan. We also give a bottom up classification in terms of simplicial toric varieties and fiber products of root stacks. [ABSTRACT FROM AUTHOR]

Two new complexes constructed by 1,4-phenylenediacetic acid (H2PDA) and 2,2'-bipyridine (2,2'-bpy), namely [Cu(PDA)(2,2'-bpy)]·5H2O (1) and [Zn2(PDA)(2,2'-bpy)2Cl2] (2), have been synthesized and characterized by single-crystal X-ray diffraction, elemental analysis, IR, and UV-Vis spectrum. Single-crystal X-ray diffraction reveals that they both crystallize in the triclinic space group of P-1. In complex 1, the Cu atom is hexa-coordinated and each asymmetric unit contains five uncoordinated water molecules that form a water cluster (H2O)10 with their symmetric equivalent. Complex 2 is a simple dimer and the Zn atom is penta-coordinated. Both in complex 1 and 2 there are π-π stacking interactions. [ABSTRACT FROM AUTHOR]

A new bisupporting metal-oxygen cluster with bicapped pseudo-Keggin compound [CuII{Cl0.5Cl(phen)}]2 {[PMoV6MoVI6O40(VIVO)2][CuII(phen)2]2}·2H2O (phen = 1,10-phenathroline) has been synthesized by hydrothermal method and characterized by elemental analysis, IR spectroscopy, TGA, XRPD, and single-crystal X-ray diffraction. The polyoxoanion consists of a bicapped vanadium Keggin polyoxoanion and two {[Cu(phen)]2}2+ subunits producing bisupporting bicapped Keggin-polyoxometalate structure. The isolated dinuclear unit [CuII{Cl0.5Cl(phen)}2]+ acts as the countercation in title compound. In the crystal structure π - π stacking interactions, multiform C-H···O and O-H···O hydrogen bonds lead to a three-dimensional network. [ABSTRACT FROM AUTHOR]

A novel copper(II) coordination polymer with the formula [Cu(pmt)(Cl)]n (pmtH=N-(2-pyridylmethylidene)taurine) has been synthesized and characterized by elemental analysis, IR and single-crystal X-ray diffraction. Each CuII atom is six-coordinated with a distorted '4+2' octahedral geometry and a pair of chlorides and sulfonates act as μ2-bridges to head the [Cu(pmt)] subunits together. The two types of rings with sharing apex Cu are alternately created and interconnected to form an interesting 1-D zigzag chain propagating along the a axis. Also, the significant weak C-H...Cl hydrogen bonds and π-π stacking interactions between the adjacent chains expanded the 1-D structure to 2-D network in the ac plane. [ABSTRACT FROM AUTHOR]

Abstract: The plasmon-mediated lasing with orders of magnitude amplification is available for a double-fishnet structure, however, it gradually disappears for multilayered fishnet stacks because of the layer-to-layer plasmon hybridization, while instead a broadened incoherent transmission with full loss compensation can always be obtained regardless of the stacking layers. [Copyright &y& Elsevier]

We generalize and clarify Gerstenhaber and Schack's ``Special Cohomology Comparison Theorem''. More specifically we obtain a fully faithful functor between the derived categories of bimodules over a prestack over a small category $ \mathcal{U}$ $ \mathcal{U}$ [ABSTRACT FROM AUTHOR]

Abstract: We show that near closed points with linearly reductive stabilizer, Artin stacks are formally locally quotient stacks by the stabilizer. We conjecture that the statement holds étale locally and we provide some evidence for this conjecture. In particular, we prove that if the stabilizer of a point is linearly reductive, the stabilizer acts algebraically on a miniversal deformation space, generalizing the results of Pinkham and Rim. We provide a generalization and stack-theoretic proof of Luna’s étale slice theorem which shows that GIT quotient stacks are étale locally quotients stacks by the stabilizer. [Copyright &y& Elsevier]

We give a construction of the moduli space of stable maps to the classifying stack Bμr of a cyclic group by a sequence of rth root constructions on $\overline {M}_{0, n}$. We prove a closed formula for the total Chern class of μr-eigenspaces of the Hodge bundle, and thus of the obstruction bundle of the genus-zero Gromov–Witten theory of stacks of the form [ℂN/μr]. We deduce linear recursions for genus-zero Gromov–Witten invariants. [ABSTRACT FROM PUBLISHER]

Abstract: Rewriting systems working on words with a center marker are considered. The derivation is done by erasing a prefix or a suffix and then adding a prefix or a suffix. This models a communication of two stacks according to a fixed protocol defined by the choice of rewriting rules. The paper systematically considers different cases of these systems and determines their expressive power. Several cases are identified where very restricted communication surprisingly yields computational universality. [ABSTRACT FROM AUTHOR]

This is the second in a series of three papers in which we investigate the rational Chow ring of the stack 0 consisting of nodal curves of genus 0. Here we define the basic classes: the classes of strata and the Mumford classes. [ABSTRACT FROM AUTHOR]

Operating systems for sensor networks must provide energy and memory-space efficient execution environments for applications because of the resource constraints of the sensor nodes. The shared-stack cooperative threads have been proposed to conserve stack memory-space and to minimize the possibility of stack overflow in the sensor operating systems. However, stack switching brings about external fragmentations in the stack space. Compaction may remove the fragmentation but the compaction overhead could degrade the performance. In this paper, we propose an efficient scheme to determine the compaction time of a shared-stack to reduce the number of compactions. For determining the time of a compaction, we evaluated the expected stack overflow time according to our stack model, which is based on the continuous time Markov chain. Our simulation results show that the number of compactions is greatly reduced and the lifetime of the sensor networks is increased with using our proposed scheme. [ABSTRACT FROM AUTHOR]

Abstract: This paper is largely concerned with constructing coarse moduli spaces for Artin stacks. The main purpose of this paper is to introduce the notion of stability on an arbitrary Artin stack and construct a coarse moduli space for the open substack of stable points. Also, we present an application to coherent cohomology of Artin stacks. [Copyright &y& Elsevier]

The transmission through a stack of identical slabs that are separated by gaps with random widths is usually treated by calculating the average of the logarithm of the transmission probability. We show how to calculate the average of the transmission probability itself with the aid of a recurrence relation and derive analytical upper and lower bounds. The upper bound, when used as an approximation for the transmission probability, is unreasonably good and we conjecture that it is asymptotically exact. [ABSTRACT FROM AUTHOR]

Abstract: The literature describes two high performance concurrent stack algorithms based on combining funnels and elimination trees. Unfortunately, the funnels are linearizable but blocking, and the elimination trees are non-blocking but not linearizable. Neither is used in practice since they perform well only at exceptionally high loads. The literature also describes a simple lock-free linearizable stack algorithm that works at low loads but does not scale as the load increases. The question of designing a stack algorithm that is non-blocking, linearizable, and scales well throughout the concurrency range, has thus remained open. This paper presents such a concurrent stack algorithm. It is based on the following simple observation: that a single elimination array used as a backoff scheme for a simple lock-free stack is lock-free, linearizable, and scalable. As our empirical results show, the resulting elimination-backoff stack performs as well as the simple stack at low loads, and increasingly outperforms all other methods (lock-based and non-blocking) as concurrency increases. We believe its simplicity and scalability make it a viable practical alternative to existing constructions for implementing concurrent stacks. [Copyright &y& Elsevier]