ppxscal/embedding_network huggingface dataset:
Image-based visual hulls
Authors: Wojciech Matusik, Chris Buehler, Ramesh Raskar, Steven J. Gortler, Leonard McMillan
Venue: Proceedings of the 27th annual conference on Computer graphics and interactive techniques (2000)

In this paper, we describe an efficient image-based approach to computing and shading visual hulls from silhouette image data. Our algorithm takes advantage of epipolar geometry and incremental computation to achieve a constant rendering cost per rendered pixel. It does not suffer from the computation complexity, limited resolution, or quantization artifacts of previous volumetric approaches. We demonstrate the use of this algorithm in a real-time virtualized reality application running off a small number of video streams.
Principled design of the modern Web architecture
Authors: Roy T. Fielding, Richard N. Taylor
Venue: Proceedings of the 22nd international conference on Software engineering (2000)

The World Wide Web has succeeded in large part because its software architecture has been designed to meet the needs of an Internet-scale distributed hypermedia system. The modern Web architecture emphasizes scalability of component interactions, generality of interfaces, independent deployment of components, and intermediary components to reduce interaction latency, enforce security, and encapsulate legacy systems. In this paper, we introduce the Representational State Transfer (REST) architectural style, developed as an abstract model of the Web architecture to guide our redesign and definition of the Hypertext Transfer Protocol and Uniform Resource Identifiers. We describe the software engineering principles guiding REST and the interaction constraints chosen to retain those principles, contrasting them to the constraints of other architectural styles. We then compare the abstract model to the currently deployed Web architecture in order to elicit mismatches between the existing protocols and the applications they are intended to support.
Riemann Invariant Manifolds for the Multidimensional Euler Equations
Authors: Tasso Lappas, Anthony Leonard, Paul E. Dimotakis
Venue: SIAM Journal on Scientific Computing (1999)

A new approach for studying wave propagation phenomena in an inviscid gas is presented. This approach can be viewed as the extension of the method of characteristics to the general case of unsteady multidimensional flow. A family of spacetime manifolds is found on which an equivalent one-dimensional (1-D) problem holds. Their geometry depends on the spatial gradients of the flow, and they provide, locally, a convenient system of coordinate surfaces for spacetime. In the case of zero-entropy gradients, functions analogous to the Riemann invariants of 1-D gas dynamics can be introduced. These generalized Riemann invariants are constant on these manifolds and, thus, the manifolds are dubbed Riemann invariant manifolds (RIM). Explicit expressions for the local differential geometry of these manifolds can be found directly from the equations of motion. They can be space-like or time-like, depending on the flow gradients. This theory is used to develop a second-order unsplit monotonic upstream-centered scheme for conservation laws (MUSCL)-type scheme for the compressible Euler equations. The appropriate RIM are traced back in time, locally, in each cell. This procedure provides the states that are connected with equivalent 1-D problems. Furthermore, by assuming a linear variation of all quantities in each computational cell, it is possible to derive explicit formulas for the states used in the 1-D characteristic problem.
Beyond speedup: PADS, the HLA and Web-based simulation
Authors: Ernest H. Page
Venue: Proceedings of the thirteenth workshop on Parallel and distributed simulation (1999)

This year's installment of the PADS "community assessment" looks at previous assessments and considers some current directions in distributed simulation and their possible relationship to PADS.
Stochastic Shortest Path Games
Authors: Stephen D. Patek, Dimitri P. Bertsekas
Venue: SIAM Journal on Control and Optimization (1999)

We consider dynamic, two-player, zero-sum games where the "minimizing" player seeks to drive an underlying finite-state dynamic system to a special terminal state along a least expected cost path. The "maximizer" seeks to interfere with the minimizer's progress so as to maximize the expected total cost. We consider, for the first time, undiscounted finite-state problems, with compact action spaces, and transition costs that are not strictly positive. We admit that there are policies for the minimizer which permit the maximizer to prolong the game indefinitely. Under assumptions which generalize deterministic shortest path problems, we establish (i) the existence of a real-valued equilibrium cost vector achievable with stationary policies for the opposing players and (ii) the convergence of value iteration and policy iteration to the unique solution of Bellman's equation.
HMDs, caves chameleon: a human-centric analysis of interaction in virtual space
Authors: Bill Buxton, George W. Fitzmaurice
Venue: ACM SIGGRAPH Computer Graphics (1998)

There are a various approaches to implementing virtual reality (VR) systems. The head mounted display (HMD) and Cave approaches are two of the best known. In this paper, we discuss such approaches from the perspective of the types of interaction that they afford. Our analysis looks at interaction from three perspectives: solo interaction, collaborative interaction in the same physical space and remote collaboration. From this analysis emerges a basic taxonomy that is intended to help systems designers make choices that better match their implementation with the needs of their application and users.
Minimal Resolutions and the Homology of Matching and Chessboard Complexes
Authors: Victor Reiner, Joel Roberts
Venue: Journal of Algebraic Combinatorics: An International Journal (2000)

We generalize work of Lascoux and J&oacute;zefiak-Pragacz-Weyman on Betti numbers for minimal free resolutions of ideals generated by 2 &times; 2 minors of generic matrices and generic symmetric matrices, respectively. Quotients of polynomial rings by these ideals are the classical Segre and quadratic Veronese subalgebras, and we compute the analogous Betti numbers for some natural modules over these Segre and quadratic Veronese subalgebras. Our motivation is two-fold:&bull; We immediately deduce from these results the irreducible decomposition for the symmetric group action on the rational homology of all chessboard complexes and complete graph matching complexes as studied by Bj&ouml;rner, Lovasz, Vre&cacute;ica and &Zcaron;ivaljevi&cacute;. This follows from an old observation on Betti numbers of semigroup modules over semigroup rings described in terms of simplicial complexes.&bull; The class of modules over the Segre rings and quadratic Veronese rings which we consider is closed under the operation of taking canonical modules, and hence exposes a pleasant symmetry inherent in these Betti numbers.
On the generation and use of TCP acknowledgments
Authors: Mark Allman
Venue: ACM SIGCOMM Computer Communication Review (1998)

This paper presents a simulation study of various TCP acknowledgment generation and utilization techniques. We investigate the standard version of TCP and the two standard acknowledgment strategies employed by receivers: those that acknowledge each incoming segment and those that implement delayed acknowledgments. We show the delayed acknowledgment mechanism hurts TCP performance, especially during slow start. Next we examine three alternate mechanisms for generating and using acknowledgments designed to mitigate the negative impact of delayed acknowledgments. The first method is to generate delayed ACKs only when the sender is not using the slow start algorithm. The second mechanism, called byte counting, allows TCP senders to increase the amount of data being injected into the network based on the amount of data acknowledged rather than on the number of acknowledgments received. The last mechanism is a limited form of byte counting. Each of these mechanisms is evaluated in a simulated network with no competing traffic, as well as a dynamic environment with a varying amount of competing traffic. We study the costs and benefits of the alternate mechanisms when compared to the standard algorithm with delayed ACKs.
Image Thresholding by Indicator Kriging
Authors: Wonho Oh, W. Brent Lindquist
Venue: IEEE Transactions on Pattern Analysis and Machine Intelligence (1999)

We consider the problem of segmenting a digitized image consisting of two univariate populations. Assume a priori knowledge allows incomplete assignment of voxels in the image, in the sense that a fraction of the voxels can be identified as belonging to population $\Pi_0$, a second fraction to $\Pi_1$, and the remaining fraction have no a priori identification. Based upon estimates of the short length scale spatial covariance of the image, we develop a method utilizing indicator kriging to complete the image segmentation.
Using a large projection screen as an alternative to head-mounted displays for virtual environments
Authors: Emilee Patrick, Dennis Cosgrove, Aleksandra Slavkovic, Jennifer A. Rode, Thom Verratti, Greg Chiselko
Venue: Proceedings of the SIGCHI conference on Human factors in computing systems (2000)

Head-mounted displays for virtual environments facilitate an immersive experience that seems more real than an experience provided by a desk-top monitor [18]; however, the cost of head-mounted displays can prohibit their use. An empirical study was conducted investigating differences in spatial knowledge learned for a virtual environment presented in three viewing conditions: head-mounted display, large projection screen, and desk-top monitor. Participants in each condition were asked to reproduce their cognitive map of a virtual environment, which had been developed during individual exploration of the environment along a predetermined course. Error scores were calculated, indicating the degree to which each participant's map differed from the actual layout of the virtual environment. No statistically significant difference was found between the head-mounted display and large projection screen conditions. An implication of this result is that a large projection screen may be an effective, inexpensive substitute for a head-mounted display.
On the Design of IEEE Compliant Floating Point Units
Authors: Guy Even, Wolfgang J. Paul
Venue: IEEE Transactions on Computers (2000)

Engineering design methodology recommends designing a system as follows: Start with an unambiguous specification, partition the system into blocks, specify the functionality of each block, design each block separately, and glue the blocks together. Verifying the correctness of an implementation then reduces to a local verification procedure. We apply this methodology for designing a provably correct IEEE rounding unit that can be used for various operations, such as addition and multiplication. First, we provide a mathematical and, hopefully, unambiguous definition of the IEEE Standard which specifies the functionality. We give explicit and concise rules for gluing the rounding unit with a floating-point adder and multiplier. We then present floating-point addition and multiplication algorithms that use the rounding unit. To the best of our knowledge, our design is the first publication that deals with detecting exceptions and trapped overflow and underflow exceptions as an integral part of the rounding unit in a floating point unit. Our abstraction level avoids bit-level representations and arguments to help clarify the functionality of the algorithm.
Systems analysis with attitude!
Authors: Maurice Abi-Raad
Venue: ACM SIGCSE Bulletin (2000)

Have you ever been overruled by your students in critical decisions relating to their learning? Have you ever attended your own classes as a guest consultant with pre-defined scope of input? Have you ever suffered from the fact that each student is different, and you have a standard program for all? Have you ever empowered your students, and watch them exceed your expectation? The only important question is whether you have the courage to throw out your safety nets and Do It. For those who are looking to be involved in an exciting, challenging, stimulating and rewarding teaching exercise, Systems Analysis with attitude is definitely it. Interested! We were too when we attempted this experiment that we do recommend to collegues in this always-evolving analysis discipline.
Similarity-Based Load Adjustment for Static Real-Time Transaction Systems
Authors: Tei-Wei Kuo, Shao-Juen Ho
Venue: IEEE Transactions on Computers (2000)

How to exploit application semantics to improve the performance of a real-time data-intensive application has been an active research topic in the past few years. Weaker correctness criteria and semantics-based concurrency control algorithms were proposed to provide more flexibility in reordering read and write events [4], [7], [8], [9], [18], [19], [22]. Distinct from past work, this paper exploits the trade-off between data consistency and system workload. The definition of similarity [8] is combined with the idea of transaction skipping to provide a theoretical foundation for reducing the workload of a transaction system. We also propose guidelines to adjust the execution frequencies of a static set of transactions and prove their correctness. The strengths of this work were verified by simulation experiments on an air traffic control example [20].
Test scheduling for core-based systems
Authors: Krishnendu Chakrabarty
Venue: Proceedings of the 1999 IEEE/ACM international conference on Computer-aided design (1999)

We present optimal solutions to the test scheduling problem for core-based systems. We show that test scheduling is equivalent to the m-processor open-shop scheduling problem and is therefore NP-complete. However, a commonly-encountered instance of this problem (m = 2) can be solved in polynomial time. For the general case (m > 2), we present a mixed-integer linear programming (MILP) model for optimal scheduling and apply it to a representative core-based system using an MILP solver. We also extend the MILP model to allow optimal test set selection from a set of alternatives. Finally, we present an efficient heuristic algorithm for handling larger systems for which the MILP model may be infeasible.
Using node merging to enhance graph coloring
Authors: Steven R. Vegdahl
Venue: ACM SIGPLAN Notices (1999)

A Chaitin-style register allocator often blocks during its simplification phase because no node in the interference graph has a degree that is sufficiently small. Typically, this is handled by node-splitting, or by optimistically continuing---and hoping that a legal N-coloring will still be found. We observe that the merging of two nodes in a graph causes a reduction in the degree of any node that had been adjacent to both. We have enhanced Chaitin's coloring algorithm so that it attempts node-merging during graph simplification; this often allows simplification to continue, while still guaranteeing a coloring for the graph. We have tested this algorithm using Appel's database of register-coloring graphs, and have compared it with Chaitin's algorithm. The merge-enhanced algorithm yields a better coloring about 8% of the time, and a worse coloring less than 0.1% of the time.
Enhancing Concept-Based Retrieval Based onMinimal Term Sets
Authors: A. H. Alsaffar, J. S. Deogun, V. V. Raghavan, H. Sever
Venue: Journal of Intelligent Information Systems (2000)

There is considerable interest in bridging the terminological gap that exists between the way users prefer to specify their information needs and the way queries are expressed in terms of keywords or text expressions that occur in documents. One of the approaches proposed for bridging this gap is based on technologies for expert systems. The central idea of such an approach was introduced in the context of a system called Rule Based Information Retrieval by Computer (RUBRIC). In RUBRIC, user query topics (or concepts) are captured in a rule base represented by an AND/OR tree. The evaluation of AND/OR tree is essentially based on minimum and maximum weights of query terms for conjunctions and disjunctions, respectively. The time to generate the retrieval output of AND/OR tree for a given query topic is exponential in number of conjunctions in the DNF expression associated with the query topic. In this paper, we propose a new approach for computing the retrieval output. The proposed approach involves preprocessing of the rule base to generate Minimal Term Sets (MTSs) that speed up the retrieval process. The computational complexity of the on-line query evaluation following the preprocessing is polynomial in m. We show that the computation and use of MTSs allows a user to choose query topics that best suit their needs and to use retrieval functions that yield a more refined and controlled retrieval output than is possible with the AND/OR tree when document terms are binary. We incorporate p-Norm model into the process of evaluating MTSs to handle the case where weights of both documents and query terms are non-binary.
The essence of objects
Authors: Benjamin C. Pierce
Venue: ACM SIGSOFT Software Engineering Notes (2000)

"The Essence of Objects" is an ongoing program of research in programming languages, type systems, and distributed programming at the University of Pennsylvania, supported by the National Science Foundation under Career grant CCR-9701826, Principled Foundations for Programming with Objects. Papers on most of the topics discussed in this outline can be found via http://www.cis.upenn.edu/bcpierce/papers.
System Management for the Three-tiered SAP AG R&ndash;3 Environment
Authors: Katherine J. Jones
Venue: International Journal of Network Management (1996)

SAP provides software which supports many systems management needs. In addition, platform providers for R&ndash;3, the open systems business application product, have integrated the hardware and software to provide R&ndash;3 systems management.
Reifying variants in configuration management
Authors: Jean-Marc Jézéquel
Venue: ACM Transactions on Software Engineering and Methodology (TOSEM) (1999)

Using a solid software configuration management (SCM) is mandatory to establish and maintain the integrity of the products of a software project throughout the project's software life cycle. Even with the help of sophisticated tools, handling the various dimensions of SCM can be a daunting (and costly) task for many projects. The contribution of this article is to (1)propose a method (based on the use creational design patterns) to simplify SCM by reifying the variants of an object-oriented software system into language-level objects and (2)show that newly available compilation technology makes this proposal attractive with respect to performance (memory footprint and execution time) by inferring which classes are needed for a specific configuration and optimizing the generated code accordingly.
Bridging strategies for VR-based learning
Authors: Tom Moher, Andrew Johnson, Stellan Ohlsson, Mark Gillingham
Venue: Proceedings of the SIGCHI conference on Human factors in computing systems: the CHI is the limit (1999)

A distributed immersive virtual environment was deployed as a component of a pedagogical strategy for teaching third grade children that the Earth is round. The displacement strategy is based on the theory that fundamental conceptual change requires an alternative cognitive starting point which doesnt invoke the features of pre-existing models. While the VR apparatus helped to establish that alternative framework, conceptual change was strongly influenced by the bridging activities which related that experience to the target domain. Simple declarations of relevance proved ineffective. A more articulated bridging process involving physical models was effective for some children, but the multiple representations employed required too much model-matching for others.
Applying the RMON standard to switched environments
Authors: Nathan Kalowski
Venue: International Journal of Network Management (1997)

As today&rsquo;s enterprise networks become increasingly complex, so Network Managers have an increasing need for effective tools to monitor and analyse them. This article discusses the RMON standard, and the groups it defines, from a practical persperspective. &copy; 1997 John Wiley & Sons, Ltd.
On the Maximum Scatter Traveling Salesperson Problem
Authors: Esther M. Arkin, Yi-Jen Chiang, Joseph S. B. Mitchell, Steven S. Skiena, Tae-Cheon Yang
Venue: SIAM Journal on Computing (1999)

We study the problem of computing a Hamiltonian tour (cycle) or path on a set of points in order to maximize the minimum edge length in the tour or path. This "maximum scatter" traveling salesperson problem (TSP) is closely related to the bottleneck TSP and is motivated by applications in manufacturing (e.g., sequencing of rivet operations) and medical imaging. In this paper, we give the first algorithmic study of these problems, including complexity results, approximation algorithms, and exact algorithms for special cases. In an attempt to model more accurately the real problems that arise in practice, we also generalize the basic problem to consider a more general measure of "scatter" in which points on a tour or path should be far not only from their immediate predecessor and successor, but also from other near-neighbors along the tour or path.
Procedure-Level Verification of Real-time Concurrent Systems
Authors: Farn Wang, Chia-Tien Lo
Venue: Real-Time Systems (1999)

We want to develop verification techniques for real-time concurrent system specifications with high-level behavior structures. This work identifies two common engineering guidelines respected in the development of real-world software projects, structured programming and local autonomy in concurrent systems, and experiments with special verification algorithm based on those engineering wisdoms. The algorithm we have adopted respects the integrity of program structures, treats each procedure as an entity instead of as a group of statements, allows local state space search to exploit the local autonomy in concurrent systems without calculating the Cartesian products of local state spaces, and derives from each procedure declaration characteristic information which can be utilized in the verification process anywhere the procedure is invoked. We have endeavored to implement our idea, test it against an abstract extension of a real-world protocol in a mobile communication environment, and report the data.
Convex Optimization Via Feedbacks
Authors: Arkadii V. Kryazhimskii
Venue: SIAM Journal on Control and Optimization (1999)

Three dynamical systems are associated with a problem of convex optimization in a finite-dimensional space. For system trajectories $ x(t) $, the ratios $ x(t)/t $ are, respectively, (i) solution tracking (staying within the solution set $ X^0 $), (ii) solution abandoning (reaching $ X^0 $ as time $ t $ goes back to the initial instant), and (iii) solution approaching (approaching $ X^0 $ as time $ t $ goes to infinity). The systems represent a closed control system with appropriate feedbacks. In typical cases, the structure of the trajectories is simple enough. For instance, for a problem of quadratic programming with linear and box constraints, solution-approaching dynamics are described by a piecewise-linear ODE with a finite number of polyhedral domains of linearity. Finding the order of visiting these domains yields an analytic resolution of the original problem; a detailed analysis is given for a particular example. A discrete-time approach is outlined.