ppxscal/embedding_network huggingface dataset:
An O(Nm)-Time Network Simplex Algorithm for the Shortest Path Problem
Authors: Donald Goldfarb, Zhiying Jin Gte
Venue: Operations Research (1999)

We present an O(nm)-time network simplex algorithm for finding a tree of shortest paths from a given node to all other nodes in a network of n nodes and m directed arcs or finding a directed cycle of negative length. The worst-case running time of this algorithm is as fast as that proved for any strongly polynomial algorithm and faster than that proved for any previously proposed simplex algorithm for this problem. We also show that this algorithm can be implemented in O(n log n) time using O((m/ log n) + n) exclusive read-exclusive write processors of a parallel random access machine.
Concurrent flip-flop and repeater insertion for high performance integrated circuits
Authors: Pasquale Cocchini
Venue: Proceedings of the 2002 IEEE/ACM international conference on Computer-aided design (2002)

For many years, CMOS process scaling has allowed a steady increase in the operating frequency and integration density of integrated circuits. Only recently, however, have we reached a point where it takes several clock cycles for global signals to traverse a complex digital system such as a modern microprocessor. Thus, interconnect latency must be taken into account in current and future design tools at the architectural as well as synthesis level. To this purpose, this work proposes a new latency-aware technique for the performance-driven concurrent insertion of flip-flops and repeaters in VLSI circuits. Overwhelming evidence showing an exponential increase in the number of pipelined interconnects with process scaling, for high-performance microprocessors as well as high-end ASICs, is also presented. This increase indicates a radical change in current design methodologies to cope with this new emerging problem.
Rejoinder: Or/Ms, Electronic Commerce, and the Virtual Informs Community
Authors: Hemant K. Bhargava, Ramayya Krishnan
Venue: INFORMS Journal on Computing (1998)

We would like to begin by thanking all the commentators for their careful review and thoughtful comments. We see three themes related to OR/MS and the Web in the various comments and suggestions made by the commentators. The first relates to electronic commerce, the second to enabling technology infrastructure, and the third to the role of the Web in serving the INFORMS community. We respond to each of these points in turn.
Smoothness prior approach to explore mean structure in large-scale time series
Authors: Genshiro Kitagawa, Tomoyuki Higuchi, Fumiyo N. Kondo
Venue: Theoretical Computer Science (2003)

This article is addressed to the problem of modeling and exploring mean value structure of large-scale time series data and time-space data. A smoothness prior modeling approach (Smoothness Prior Analysis of Time Series, Lecture Notes in Statistics, vol. 116, Springer, New York, 1996.) is taken. In this approach, the observed series are decomposed into several components each of which are expressed by smoothness priors models. In the analysis of POS and GPS data, various useful information were extracted by this decomposition, and result in discoveries in these areas.
Segmentation and length estimation of 3D discrete curves
Authors: David Coeurjolly, Isabelle Debled-Rennesson, Olivier Teytaud
Venue: Digital and image geometry: advanced lectures (2001)

We propose in this paper an arithmetical definition of 3-D discrete lines as well as an efficient construction algorithm. From this notion, an algorithm of 3-D discrete lines segmentation has been developed. It is then used to calculate the length of a discrete curve. A proof of the multigrid convergence of length estimators is presented.
The shortest disjunctive normal form of a random Boolean function
Authors: Nicholas Pippenger
Venue: Random Structures Algorithms (2003)

This paper gives a new upper bound for the average length l(n) of the shortest disjunctive normal form for a random Boolean function of n arguments, as well as new proofs of two old results related to this quantity. We consider a random Boolean function of n arguments to be uniformly distributed over all 22n such functions. (This is equivalent to considering each entry in the truth-table to be 0 or 1 independently and with equal probabilities.) We measure the length of a disjunctive normal form by the number of terms. (Measuring it by the number of literals would simply introduce a factor of n into all our asymptotic results.) We give a short proof using martingales of Nigmatullin's result that almost all Boolean functions have the length of their shortest disjunctive normal form asymptotic to the average length l(n). We also give a short information-theoretic proof of Kuznetsov's lower bound l(n) ≥ (1 + o(1)) 2n/log n log log n. (Here log denotes the logarithm to base 2.) Our main result is a new upper bound l(n) ≤ (1 + o(1)) H(n) 2n/log n log log n, where H(n) is a function that oscillates between 1.38826... and 1.54169 .... The best previous upper bound, due to Korshunov, had a similar form, but with a function oscillating between 1.581411... and 2.621132 .... The main ideas in our new bound are (1) the use of Rödl's "nibble" technique for solving packing and covering problems, (2) the use of correlation inequalities due to Harris and Janson to bound the effects of weakly dependent random variables, and (3) the solution of an optimization problem that determines the sizes of "nibbles" and larger "bites" to be taken at various stages of the construction.
Investigating how individuals conceptually and physically structure file folders for electronic bookmarks: the example of the financial services industry
Authors: Lisa Gottlieb, Juris Dilevko
Venue: Journal of the American Society for Information Science and Technology (2003)

Personal preferences in the development of categorical folders for bookmarks are examined in terms of both the choice and definition of folder domain and the overall structure of the folder system. Study participants from the financial industry were asked to organize the same set of finance-related bookmarks from a given list, as opposed to describing their organizational approaches using their own personal bookmarks, so that the organizational systems could be compared across the sample. The selection of folder domain is influenced by contextual factors such as intended use and relevancy to current projects. Similarly, the structure of the overall folder system was determined in part by participants' navigational preferences. While the majority of participants created folders that cover the topics of finance, government, accounting, news, law, and tax, the actual definition of these folders and the criteria for inclusion vary across the sample. Furthermore, these criteria cannot be readily discerned from the folder system itself. Variation in folder domain and definition could adversely affect the utility of bookmark management systems for multiple users that involve some degree of standardization. The same variation in interpretation of seemingly identical folders suggests that systems with automatic categorization would not provide users with enough flexibility in how they could organize and access their bookmarks.
A web-based support environment for software engineering experiments
Authors: Erik Arisholm, Dag I. K. Sjøberg, Gunnar J. Carelius, Yngve Lindsjørn
Venue: Nordic Journal of Computing (2002)

The software engineering communities frequently propose new software engineering technologies, such as new development techniques, programming languages and tools, without rigorous scientific evaluation. One way to evaluate software engineering technologies is through controlled experiments where the effects of the technology can be isolated from confounding factors, i.e., establishing cause-effect relationships. For practical and financial reasons, however, such experiments are often quite unrealistic, typically involving students in a class-room environment solving small pen-and-paper tasks. A common criticism of the results of the experiments is their lack of external validity, i.e., that the results are not valid outside the experimental conditions. To increase the external validity of the experimental results, the experiments need to be more realistic. The realism can be increased using professional developers as subjects who conduct larger experimental tasks in their normal work environment. However, the logistics involved in running such experiments are tremendous. More specifically, the experimental materials (e.g., questionnaires, task descriptions, code and tools) must be distributed to each programmer, the progress of the experiment needs to be controlled and monitored, and the results of the experiment need to be collected and analyzed. To support this logistics for large-scale, controlled experiments, we have developed a web-based experiment support environment called SESE. This paper describes SESE, its development and the experiences from using it to conduct a large controlled experiment in industry.
Hardware support for real-time embedded multiprocessor system-on-a-chip memory management
Authors: Mohamed Shalan, Vincent J. Mooney,  III
Venue: Proceedings of the tenth international symposium on Hardware/software codesign (2002)

The aggressive evolution of the semiconductor industry --- smaller process geometries, higher densities, and greater chip complexity --- has provided design engineers the means to create complex high-performance Systems-on-a-Chip (SoC) designs. Such SoC designs typically have more than one processor and huge memory, all on the same chip. Dealing with the global on- chip memory allocation/de-allocation in a dynamic yet deterministic way is an important issue for the upcoming billion transistor multiprocessor SoC designs. To achieve this, we propose a memory management hierarchy we call Two-Level Memory Management. To implement this memory management scheme --- which presents a paradigm shift in the way designers look at on-chip dynamic memory allocation --- we present a System-on-a-Chip Dynamic Memory Management Unit (SoCDMMU) for allocation of the global on-chip memory, which we refer to as Level Two memory management (Level One is the operating system management of memory allocated to a particular on-chip Processing Element). In this way, processing elements (heterogeneous or non-heterogeneous hardware or software) in an SoC can request and be granted portions of the global memory in a fast and deterministic time (for an example of a four processing element SoC, the dynamic memory allocation of the global on-chip memory takes sixteen cycles per allocation/deallocation in the worst case). In this paper, we show how to modify an existing Real-Time Operating System (RTOS) to support the new proposed SoCDMMU. Our example shows a multiprocessor SoC that utilizes the SoCDMMU has 440% overall speedup of the application transition time over fully shared memory that does not utilize the SoCDMMU.
Efficiency of multigrid methods for the numerical simulation of coupled fluid-solid problems
Authors: Michael Schäfer, Sebastian Meynen, Rolf Sieber, Ilka Teschauer
Venue: Scientific computing and applications (2001)

A methodology for the usage of multigrid techniques for the numerical solution of coupled fluid-solid problems is presented. The treatment of thermal and/or mechanical fluid-solid coupling is based on the concept of block-structured moving grids also allowing for the handling of complex geometries. Discretisation is performed by a second-order finite-volume approach and the resulting algebraic systems are solved with a global nonlinear multigrid method with a pressure-correction based scheme as smoother and coarse grid solver. By a number of numerical examples involving various coupling mechanisms the method is investigated with respect to its accuracy and numerical efficiency.
On Solutions of the Travelling Wave Type in a Transportation Model
Authors: N. K. Khachatryan
Venue: Automation and Remote Control (2003)

A model of long-distance railway freight traffic with multiple intermediate stations and a given system of monitoring was described. The ACM Portal is published by the Association for Computing Machinery. Copyright © 2010 ACM, Inc. Terms of Usage Privacy Policy Code of Ethics Contact Us Useful downloads: Adobe Acrobat QuickTime Windows Media Player Real Player
Deciding the guarded fragments by resolution
Authors: Hans de Nivelle, Maarten de Rijke
Venue: Journal of Symbolic Computation (2003)

The guarded fragment (GF) is a fragment of first-order logic that has been introduced for two main reasons: first, to explain the good computational and logical behaviour of propositional modal logics. Second, to serve as a breeding ground for well-behaved process logics. In this paper we give resolution-based decision procedures for the GF and for the loosely guarded fragment (LGF) (sometimes also called the pairwise guarded fragment). By constructing an implementable decision procedure for the GF and for the LGF, we obtain an effective procedure for deciding modal logics that can be embedded into these fragments. The procedures have been implemented in the theorem prover Bliksem.
A Second Order Stochastic Network Equilibrium Model, I: Theoretical Foundation
Authors: David Watling
Venue: Transportation Science (2002)

Existing models of stochastic network equilibrium route choice in transport networks are able to represent exogenously specified variations in drivers' actual or perceived travel costs, but assume throughout that flows are deterministic. In this paper, a new notion of equilibrium is presented based on stochastic flow variables, in which the impact of variable flows on the variability in travel costs is endogenously handled. Firstly, a very general notion of equilibrium is deduced as a fixed point condition on the joint probability distribution of network flows. Then, an approximation to this condition is derived, which operates by equilibrating moments of ordern and below of the joint flow probability distribution, and is termed a Generalized Stochastic User Equilibrium of ordern, being denoted GSUE( n). The GSUE(1) model is seen to be a conventional Stochastic User Equilibrium. The paper goes on to focus on the second order model, GSUE(2). Conditions are presented to guarantee the existence of GSUE(2) solutions. Conditions are deduced to guarantee (a) uniqueness of solutions in networks with a single interzonal movement, and (b) proximity of solutions in networks with multiple interzonal movements. Finally, a simple example is presented.
A Simple KNN Algorithm for Text Categorization
Authors: Pascal Soucy, Guy W. Mineau
Venue: Proceedings of the 2001 IEEE International Conference on Data Mining (2001)

Text categoriztion (also called text classification) is the process of identifying the class to which a text document belongs. This paper proposes to use a simple non-weighted feature KNN algorithm for text caegoriztion. We propose to use a feature selection method that finds the relevant features for the learning task at hand using feature interaction (based on word interdependencies).
Specification of parameterized programs: persistency revisited
Authors: Yngve Lamo, Michal Walicki
Venue: Nordic Journal of Computing (2001)

We revisit the concept of persistent functor pointing out its well known limitations for the purpose of describing the semantics of specifications of parameterized data types (PDTs). We introduce a more general notion of a semantic functor F which requires only that the parameter algebra A is a subalgebra of its image F(A). We illustrate the flexibility and advantages of the proposed construction by examples.The main part of the paper concerns the syntactic restrictions on the specifications which allow one to define the semantics of PDTs in this way. One obtains the possibilities to: 1) preserve the carriers of the parameter algebras (corresponding to the classical persistency), or 2) extending carriers of the parameter algebras. The later situation means that one can, typically, use free functor semantics. In this case, one also has two further options: either 2a) to restrict the validity of the axioms from the parameter specification to apply only to the old elements (from the carriers of the parameter algebras), or 2b) to extend them to apply also to the new elements added to the carrier.We discuss the mechanism of actual parameter passing, actualization of the semantic functors and refer to an earlier work for the counterparts of the vertical and horisontal composition theorems, as well as the notion of refinement of PDTs which amounts to the refinement of the structure of the specified data type.
Graphical interaction with heterogeneous databases
Authors: T. Catarci, G. Santucci, J. Cardiff
Venue: The VLDB Journal &mdash; The International Journal on Very Large Data Bases (1997)

During the past few years our research efforts have been inspired by two different needs. On one hand, the number of non-expert users accessing databases is growing apace. On the other, information systems will no longer be characterized by a single centralized architecture, but rather by several heterogeneous component systems. In order to address such needs we have designed a new query system with both user-oriented and multidatabase features. The system's main components are an adaptive visual interface, providing the user with different and interchangeable interaction modalities, and a &ldquo;translation layer&rdquo;, which creates and offers to the user the illusion of a single homogeneous schema out of several heterogeneous components. Both components are founded on a common ground, i.e. a formally defined and semantically rich data model, the Graph Model, and a minimal set of Graphical Primitives, in terms of which general query operations may be visually expressed. The Graph Model has a visual syntax, so that graphical operations can be applied on its components without unnecessary mappings, and an object-based semantics. The aim of this paper is twofold. We first present an overall view of the system architecture and then give a comprehensive description of the lower part of the system itself. In particular, we show how schemata expressed in different data models can be translated in terms of Graph Model, possibly by exploiting reverse engineering techniques. Moreover, we show how mappings can be established between well-known query languages and the Graphical Primitives. Finally, we describe in detail how queries expressed by using the Graphical Primitives can be translated in terms of relational expressions so to be processed by actual DBMSs.
CCAM: A Connectivity-Clustered Access Method for Aggregate Queries on Transportation Networks: A Summary of Results
Authors: Shashi Shekhar, Duen-Ren Liu
Venue: Proceedings of the Eleventh International Conference on Data Engineering (1995)

CCAM is an access method for general networks. It uses connectivity clustering. The nodes of the network are assigned to disk pages via the graph partitioning approach to maximize the CRR, i.e., the chances that a pair of connected nodes are allocated to a common page of the file. CCAM supports the operations of insert, delete, create, and find as well as the new operations, get-A-successor and get-successors, which retrieve one or all successors of a node to facilitate aggregate computations on networks. CCAM includes methods for static clustering, as well as dynamic incremental reclustering, to maintain, high CRR, in the face of updates without incurring high overheads. Experimental analysis indicates that CCAM can outperform many other access methods for network operations.
Dynamics in high-dimensional model gene networks
Authors: K. Kappler, R. Edwards, L. Glass
Venue: Signal Processing (2003)

We consider dynamics in a class of ordinary differential equations representing a simplified model of a genetic network. In this network, the model genes control the production rates of products of other genes by a logical function. Thus, the concentration of a particular gene's product is driven either up or down depending on the particular combination of activity states (active or inactive, i.e., gene product above or below threshold) of a set of relevant 'input' genes. The interactions are based on binary functions but the evolution of gene product concentrations is continuous in time, unlike the discrete-time Boolean networks of Kauffman and others. Numerical methods allow rapid and accurate integration of the model equations. Also, theory now allows analytic confirmation of numerically observed attractors. This enables us to determine changes in the distribution of dynamical properties (attractor types) of random networks as the size of the networks increase and as the number of inputs to each gene increases.
Organizations As Adaptive Systems in Complex Environments: the Case of China
Authors: Max Boisot, John Child
Venue: Organization Science (1999)

This paper treats organizations as adaptive systems that have to match the complexity of their environments. The nature of this complexity is analyzed by linking an institutional InformationSpace (I-Space) framework to the work of complexity theorists. The I-Space framework identifies the codification, abstraction, and diffusion of information as cultural attributes. Codification involves the assignment of data to categories, thus giving them form. Abstraction involves a reduction in the number of categories to which data needs to be assigned for a phenomenon to be apprehended. Information is diffused through populations of data-processing agents, thus constituting the diffusion dimension. Complexity theorists have identified the stability and structure of algorithmic information complexity in a way that corresponds to levels of codification and abstraction. Their identification of system parts and the richness of cross-coupling draws attention to the fabric of information diffusion. We discuss two modes of adaptation to complex environments: complexity reduction and complexity absorption. Complexity reduction entails getting to understand the complexity and acting on it directly, including attempts at environmental enactment. Complexity absorption entails creating options and risk hedging strategies, often through alliances. The analysis, and its practical utility, is illustrated with reference to China, the world's largest social system. Historical factors have shaped the nature of complexity in China, giving it very different characteristics than those typical of Western industrial countries. Its organizations and other social units have correspondingly handled this complexity through a strategy of absorption rather than the reduction strategy characteristic of Western societies. Western firms operating in China therefore face a choice between maintaining their norms of complexity reduction or adopting a strategy of complexity absorption that is more consistent with Chinese culture. The specifics of these policy alternatives are explored, together with their advantages and disadvantages. The paper concludes with the outlines of a possible agenda for future research, focusing on the investigation of complexity handling modes and the contingencies which may bear upon the choice between them.
2D large Eddy simulation of highly stratified flow: the stepwise structure effect
Authors: Sabeur Berrabaa Philippe Fraunie Michel Crochet
Venue: Scientific computing and applications (2001)

Large Eddy Simulations (LES) of the evolution of a stratified flow are presented for an horizontally towed grid in a linearly stratified flow, and indication of the well known stepwise effect are apparent and show a clear temporal variation.Detailed analysis of the unsteady turbulent stratified flow is given at the light of Phillips [17] and Posmentier [18] mechanism, in function of values of the Richardson number, and the influence of an initial internal wave is pointed out.