ppxscal/embedding_network huggingface dataset:
KDD-2002 workshop report fractals and self-similarity in data mining: issue and approaches
Authors: Jafar Adibi, Christos Faloutsos
Venue: ACM SIGKDD Explorations Newsletter (2002)

In this report we provide a summary of the first workshop on application of self-similarity and fractals in data mining: issues and approaches held in conjunction with ACM SIGKDD 2002, July 23 at Edmonton, Alberta, Canada.
Origin-Based Algorithm for the Traffic Assignment Problem
Authors: Hillel Bar-Gera
Venue: Transportation Science (2002)

We present an origin-based algorithm for the traffic assignment problem, which is similar conceptually to the algorithm proposed by Gallager and Bertsekas for routing in telecommunication networks. Apart from being origin-based, the algorithm is different from other algorithms used so far for the traffic assignment problem by its restriction to acyclic solutions and by the use of approach proportions as solution variables. Projected quasi-Newton search directions are used to shift flows effectively and to eliminate residual flows. Experimental results comparing the proposed algorithm with the state-of-the-practice algorithm of Frankand Wolfe demonstrate the algorithm's excellent convergence performance, especially when highly accurate solutions are needed. Reasonable memory requirements make this algorithm applicable to large-scale networks. The resulting solution has an immediate route flow interpretation, thus providing equivalent detail to route-based solutions.
Resolution adaptive volume sculpting
Authors: Eric Ferley, Marie-Paule Cani, Jean-Dominique Gascuel
Venue: Graphical Models (2001)

We propose a sculpture metaphor based on a multiresolution volumetric representation. It allows the user to model both precise and coarse features while maintaining interactive updates and display rates. The modelled surface is an iso-surface of a scalar field, which is sampled on an adaptive hierarchical grid that dynamically subdivides or undivides itself. Field modifications are transparent to the user: The user feels as if he were directly interacting with the surface via a tool that either adds or removes "material." Meanwhile, the tool modifies the scalar field around the surface, its size and shape automatically guiding the underlying grid subdivision. In order to give an interactive feedback whatever the tool's size, tools are applied in an adaptive way, the grid being always updated from coarse to fine levels. This maintains interactive rates even for large tool sizes. It also enables the user to continuously apply a tool, with an immediate coarse-scale feedback of the multiple actions being provided. A dynamic level-of-detail (LOD) mechanism ensures that the iso-surface is displayed at interactive rates regardeless of the zoom value; surface elements, generated and stored at each level of resolution, are displayed depending on their size on the screen. The system may switch to a coarser surface display during user actions, thus always ensuring interactive visual feedback. Two applications illustrate the use of this system: First, complex shapes with both coarse and fine features can be sculpted from scratch. Second, we show that the system can be used to edit models that have been converted from a mesh representation.
Optimal Exercise Policies and Simulation-Based Valuation for American-Asian Options
Authors: Rongwen Wu, Michael C. Fu
Venue: Operations Research (2003)

American-Asian options are average-price options that allow early exercise. In this paper, we derive structural properties for the optimal exercise policy, which are then used to develop an efficient numerical algorithm for pricing such options. In particular, we show that the optimal policy is a threshold policy: The option should be exercised as soon as the average asset price reaches a characterized threshold, which can be written as a function of the asset price at that time. By exploiting this and other structural properties, we are able to parameterize the exercise boundary, and derive gradient estimators for the option payoff with respect to the parameters of the model. These estimators are then incorporated into a simulation-based algorithm to price American-Asian options. Computational experiments carried out indicate that the algorithm is very competitive with other recently proposed numerical algorithms.
Sortability of vector partitions
Authors: F. K. Hwang, J. S. Lee, Y. C. Liu, U. G. Rothblum
Venue: Discrete Mathematics (2003)

Some combinatorial properties of partitioning points in R1 have recently been well studied. We extend this study to points in Rd with the hope to benefit clustering and optimal partition problems in Rd.
Non-isotropic Gevery hypoellipticity for Grushin operators
Authors: Yoshiaki Hashimoto, Takaaki Hoshino, Tadato Matsuzawa
Venue: Publications of the Research Institute for Mathematical Sciences (2002)

We shall determine non-isotropic Gevrey exponents for general Grushin operators based on the results given in the paper [26], where a method to determine isotropic (worst) Gevrey exponents was given. The ideas of the bracket calculus given in the paper [2] and FBI-transformation given in the paper [5] are also useful.
Quantitative Analysis of a Hybrid Replication with Forwarding Strategy for Efficient and Uniform Location Management in Mobile Wireless Networks
Authors: Ing-Ray Chen, Baoshan Gu
Venue: IEEE Transactions on Mobile Computing (2003)

A location management scheme in wireless networks must effectively handle both user location update and search operations. Replication and forwarding are two well-known techniques to reduce user search and update costs, respectively, with replication being most effective when the call to mobility ratio (CMR) of the user is high, while forwarding is most effective when the CMR value is low. Thus, based on the user's CMR, the system can adopt a CMR threshold-based scheme such that if the user's CMR is lower than a threshold, then the system applies the forwarding scheme; otherwise, it applies the replication scheme. Applying different location management schemes based on per-user CMR values introduces undesirable high complexity in managing and maintaining location-related information stored in the system as different system support mechanisms must be applied to different users. In this paper, we quantitatively analyze a hybrid replication with forwarding scheme that can be uniformly applied to all users. The most striking feature of the hybrid scheme is that it can determine and apply the optimal number of replicas and forwarding chain length on a per-user basis to minimize the communication cost due to location management operations while still being able to use the same data structure and algorithm to execute location management operations in a uniform way for all users. We develop a stochastic Petri net model to help gather this information and show how the information obtained statically can be used efficiently by the system at runtime to determine the optimal number of replicas and forwarding chain length when given a user's profile. We show that the proposed hybrid scheme outperforms both pure replication and forwarding schemes, as well as the CMR threshold-based scheme under all CMR values.
L-proximities and totally bounded pointwise L-uniformities
Authors: Fu-Gui Shi, Jie Zhang, Chong-You Zheng
Venue: Fuzzy Sets and Systems (2003)

In this paper, we shall develop the study of connections between L-(quasi-)proximities in the sense of Katsaras-Liu-Artico--Moresco and pointwise L-(quasi-)uniformities in the sense of Shi. We shall prove that there exists a one-to-one correspondence between L-(quasi-)proximity spaces and totally bounded pointwise L-(quasi-)uniform spaces.
Combining Problem Structure with Basis Reduction to Solve a Class of Hard Integer Programs
Authors: Quentin Louveaux, Laurence A. Wolsey
Venue: Mathematics of Operations Research (2002)

Recently Aardal et al. (2000) have successfully solved some small, difficult, equality-constrained integer programs by using basis reduction to reformulate the problems as inequality-constrained integer programs in a different space. Here, we adapt their method to solve integer programs that are larger but have special structure. The practical problem motivating this work is a variant of the market share problem. More formally, the problem can be viewed as finding a matrixX ? Z mn+ satisfyingXA =C,BX =D, whereA,B,C,D are matrices of compatible dimensions, and the approach requires us to find a reduced basis of the lattice L = { X ? Zm x n :XA = 0,BX = 0}.The main topic of this paper is a study of the lattice L. It is shown that an integer basis of L can be obtained by taking the Kronecker product of vectors from integer bases of two much smaller lattices. Furthermore, the resulting basis is a reduced basis if the integer bases of the two small lattices are reduced bases and a suitable ordering is chosen.Finally, some limited computational results are presented showing the benefits of making use of the problem structure.
XML-enabled workflow management for e-services across heterogeneous platforms
Authors: German Shegalov, Michael Gillmann, Gerhard Weikum
Venue: The VLDB Journal &mdash; The International Journal on Very Large Data Bases (2001)

Advanced e-services require efficient, flexible, and easy-to-use workflow technology that integrates well with mainstream Internet technologies such as XML and Web servers. This paper discusses an XML-enabled architecture for distributed workflow management that is implemented in the latest version of our Mentor-lite prototype system. The key asset of this architecture is an XML mediator that handles the exchange of business and flow control data between workflow and business-object servers on the one hand and client activities on the other via XML messages over http. Our implementation of the mediator has made use of Oracle's XSQL servlet. The major benefit of the advocated architecture is that it provides seamless integration of client applications into e-service workflows with scalable efficiency and very little explicit coding, in contrast to an earlier, Java-based, version of our Mentor-lite prototype that required much more code and exhibited potential performance problems.
Specifying a role-based guide for learning to work with an enterprise framework
Authors: Wilhelm Hasselbring, Ralph van den Houdt
Venue: Software&mdash;Practice Experience (2002)

Learning to work with enterprise frameworks requires considerable effort, because of the inherent complexity of all the knowledge that is needed. However, different roles in project teams need to learn different knowledge components according to the different tasks to be performed. A role-based guide that has been developed for new developers in the California projects at the software house International Business Systems, Inc. (IBS) Consist is presented. The California projects develop financial applications based on the IBM SanFrancisco enterprise framework. The requirement for this guide originates in the need to guide (new) project members in learning the required skills for being able to work productively after focused training for the California projects.The starting point for this guide is the IBS development process. The individual tasks during the different phases in the process are specified by means of the Unified Modeling Language (UML) use case diagrams. An important property is that the guide is role-based to allow new project members to focus on their roles in the project, while learning to work with the framework. For each role, a UML activity diagram guides one to find the right paths for learning the required skills (which we call knowledge components) for the particular project role. The knowledge components are related to the tasks in the development process and to the roles. For all roles, at least some basic knowledge of the UML is required. Therefore, it is reasonable to specify this learning guide by means of the UML. This paper illustrates the use of the UML for specifying such a guide in a specific setting, namely the California projects of IBS Consist.
Examples of non-uniqueness of almost-unidirectional gas flow
Authors: Pavel Šolín, Karel Segeth
Venue: Mathematics and Computers in Simulation (2003)

Modeling of non-linear phenomena always brings the question of uniqueness of the exact as well as numerical solution. The paper is devoted to the non-unique behavior of gases, which has been observed in special axisymmetric nozzles at transonic flow regimes. We describe the flow by means of the compressible Euler equations. Surprisingly, the non-uniqueness is recorded already by the simplest stationary quasi-one-dimensional model. In this case, we prove the non-uniqueness analytically. The non-unique behavior is present also in the three-dimensional model, which we illustrate numerically using an original mass-conserving axisymmetric finite volume scheme. Numerical example of non-unique solutions corresponding to an axisymmetric nozzle of a complicated geometry shows a good agreement between the quasi-one-dimensional analytical and axisymmetric three-dimensional numerical results.
Case study: cellar scaffold extraction using crest point for volume rendering
Authors: Jiuxiang Hu, Page D. Baluch, Anshuman Razdan, Gregory M. Nielson, Gerald E. Farin, David G. Capco
Venue: Proceedings of the symposium on Data visualisation 2003 (2003)

Extraction of scaffolds, such as the meiotic spindles, a 3D tubular framework consisting of the microtubules, from conforcal laser scanning microscopy (CLSM) data of a cell is a challenge in biological image processing. It is of major importance in the research of microtubule anchor proteins, and molecular motor mechanics. However, the scaffold is hidden within CLSM data due to the nature of light excitation, and is difficult to visualize using traditional opacity and color transfer functions that depend only on local intensity. In this paper, we treat 3D CLSM data as a hyper-surface in R4, and show that the crest points of the hyper-surface correspond to the centerline of the hidden scaffold. We propose an automatic approach to extract the hidden scaffold from CLSM data. First, the spindle from the large data set is segmented using Weibull E-SD fields. We, next, apply the Savitzky-Golay (S-G) filter and Gaussian convolution to reduce the noise in the data and calculate the first and second derivatives. Lastly, direct volume rendering using ray casting is applied to visualize the volume data. We combine the local intensity and maximum curvature information to decide the opacity transfer function. Promising results are shown on simulated data sets as well as real CLSM data of mouse egg.
A Dynamic Airline Seat Inventory Control Model and Its Optimal Policy
Authors: Youyi Feng, Baichun Xiao
Venue: Operations Research (2001)

We consider an airline seat inventory control problem with multiple origins, one hub, and one destination. Passengers from the origins fly to the destination via the hub. Seat capacity of the hub-destination flight is fixed. Demands at origins are assumed to obey the Poisson process. To maximize the expected revenue, management faces decisions on allocating seats among competing origin-destination routes. This study presents a stochastic control model and develops optimal control rules. The basic model is subsequently distended to consider multiple fares on each route, time-dependent demands, and booking control on an extended network. A numerical example shows that optimal seat control is simple and efficient.
Lower Bounds for the Quadratic Assignment Problem Based Upon a Dual Formulation
Authors: Peter Hahn, Thomas Grant
Venue: Operations Research (1998)

A new bounding procedure for the Quadratic Assignment Problem (QAP) is described which extends the Hungarian method for the Linear Assignment Problem (LAP) to QAPs, operating on the four dimensional cost array of the QAP objective function. The QAP is iteratively transformed in a series of equivalent QAPs leading to an increasing sequence of lower bounds for the original problem. To this end, two classes of operations which transform the four dimensional cost array are defined. These have the property that the values of the transformed objective function Z' are the corresponding values of the "old" objective function Z, shifted by some amount C. In the case that all entries of the transformed cost array are nonnegative, then C is a lower bound for the initial QAP. If, moreover, there exists a feasible solution U to the QAP, such that its value in the transformed problem is zero, then C is the optimal value of Z and U is an optimal solution for the original QAP. The transformations are iteratively applied until no significant increase in constant C as above is found, resulting in the so called Dual Procedure (DP). Several strategies are listed for appropriately determining C, or equivalently, transforming the cost array. The goal is the modification of the elements in the cost array to obtain new equivalent problems that bring the QAP closer to solution. In some cases the QAP is actually solved, though solution is not guaranteed. The close relationship between the DP and the Linear Programming formulation of Adams and Johnson is presented. The DP attempts to solve Adams and Johnson's CLP, a continuous relaxation of a linearization of the QAP. This explains why the DP produces bounds close to the optimum values for CLP calculated by Johnson in her dissertation and by Resende, et al. in their Interior Point Algorithm for Linear Programming. The benefit of using DP within a branch-and-bound algorithm is described. Then, two versions of DP are tested on the Nugent test instances from size 5 to size 30, as well as several other test instances from QAPLIB. These compare favorably with earlier bounding methods.
A Scaling Scheme and Optimization Methodology for Deep Sub-Micron Interconnect
Authors: Soo-Youn Oh, Khalid Rahmat, O. Sam Nakagawa, J. Moll
Venue: Proceedings of the 1996 International Conference on Computer Design, VLSI in Computers and Processors (1996)

Significant increases in chip yield can result if faulty logic cells and wiring in Field Programmable Gate Arrays (FPGAs) can be isolated from the remainder of the circuitry to retain a completely usable chip. Utilizing the principle of node-covering, a routing discipline has been developed that allows each logic cell in an FPGA to cover -- to be able to replace -- its neighbor in a row. An FPGA is factory-reconfigured such that a faulty cell is replaced by its cover, which in turn is replaced by its own cover, and so on until a spare cell in the row is reached. Since wiring channel area is a major portion of chip area in an FPGA, new techniques are also proposed for tolerating wiring faults. As with faulty logic cells, faulty wiring portions are replaced by adjacent ones, until eventually a spare wiring portion is reached. Compared to other techniques for fault tolerance in FPGAs, these methods are shown to provide significantly greater yield improvement.
Using JessTab to Integrate Protégé and Jess
Authors: Henrik Eriksson
Venue: IEEE Intelligent Systems (2003)

Integration with external systems such as problem solvers is becoming increasingly important for ontology development and knowledge-modeling tools. JessTab is an extension to the Protégé framework that allows you to take advantage of the Jess performance system. JessTab supports declarative mapping of sections of Protégé knowledge bases to the Jess knowledge representation and adds functionality for operations on ontologies and knowledge bases.
Real-time taxi dispatching using Global Positioning Systems
Authors: Ziqi Liao
Venue: Communications of the ACM (2003)

Hailing a taxi in Singapore now employs the latest positioning technology for matching passengers with the nearest available cabs, thus achieving greater productivity and customer satisfaction.
Mastering leadership
Authors: Ubiquity staff
Venue: Ubiquity (2002)

Richard Strozzi-Heckler on moving to the next level.
The Fractional Representation Approach to Synthesis Problems: An Algebraic Analysis Viewpoint Part II: Internal Stabilization
Authors: A. Quadrat
Venue: SIAM Journal on Control and Optimization (2003)

In this second part of the paper [A. Quadrat, SIAM J. Control Optim., 40 (2003), pp. 266--299], we show how to reformulate the fractional representation approach to synthesis problems within an algebraic analysis framework. In terms of modules, we give necessary and sufficient conditions for internal stabilizability. Moreover, we characterize all the integral domains A of SISO stable plants such that every MIMO plant---defined by means of a transfer matrix whose entries belong to the quotient field K=Q(A) of A---is internally stabilizable. Finally, we show that this algebraic analysis approach allows us to recover on the one hand the approach developed in [M. C. Smith, IEEE Trans. Automat. Control, 34 (1989), pp. 1005--1007] and on the other hand the ones developed in [K. Mori and K. Abe, SIAM J. Control Optim., 39 (2001), pp. 1952--1973; S. Shankar and V. R. Sule, SIAM J. Control Optim., 30 (1992), pp. 11--30; V. R. Sule, SIAM J. Control Optim., 32 (1994), pp. 1675--1695; M. Vidyasagar, H. Schneider, and B. A. Francis, IEEE Trans. Automat. Control, 27 (1982), pp. 880--894; M. Vidyasagar, Control System Synthesis: A Factorization Approach, MIT Press, Cambridge, MA, 1985].
High-level net processes
Authors: Hartmut Ehrig, Kathrin Hoffmann, Julia Padberg, Paolo Baldan, Reiko Heckel
Venue: Formal and natural computing (2002)

The notion of processes for low-level Petri nets based on occurrence nets is well known and it represents the basis for the study of the non-sequential behavior of Petri nets. Processes for high-level nets N are often defined as processes of the low level net Flat(N) which is obtained from N via a construction called "flattening". In this paper we define high-level processes for high-level nets based on a suitable notion of high-level occurrence nets. The flattening of a high-level occurrence net is in general not a low-level occurrence net, due to so called "assignment conflicts" in the high-level net. The main technical result is a syntactical characterization of assignment conflicts. But the main focus of this paper is a conceptual discussion of future perspectives of high-level net processes including concurrency and data type aspects. Specifically, in the second part of the paper, we discuss possible extensions of high-level net processes, which are formally introduced for algebraic high-level nets in the first part of this paper. Of special interest are high-level processes with data type behavior, amalgamation, and other kinds of constructions, which are essential aspects for a proposed component concept for high-level nets.
Efficient computation of location depth contours by methods of computational geometry
Authors: Kim Miller, Suneeta Ramaswami, Peter Rousseeuw, J. Antoni Sellarès, Diane Souvaine, Ileana Streinu, Anja Struyf
Venue: Statistics and Computing (2003)

The concept of location depth was introduced as a way to extend the univariate notion of ranking to a bivariate configuration of data points. It has been used successfully for robust estimation, hypothesis testing, and graphical display. The depth contours form a collection of nested polygons, and the center of the deepest contour is called the Tukey median. The only available implemented algorithms for the depth contours and the Tukey median are slow, which limits their usefulness. In this paper we describe an optimal algorithm which computes all bivariate depth contours in O(n2) time and space, using topological sweep of the dual arrangement of lines. Once these contours are known, the location depth of any point can be computed in O(log2 n) time with no additional preprocessing or in O(log n) time after O(n2) preprocessing. We provide fast implementations of these algorithms to allow their use in everyday statistical practice.