ppxscal/embedding_network huggingface dataset:
Sampling plausible solutions to multi-body constraint problems
Authors: Stephen Chenney, D. A. Forsyth
Venue: Proceedings of the 27th annual conference on Computer graphics and interactive techniques (2000)

Traditional collision intensive multi-body simulations are difficult to control due to extreme sensitivity to initial conditions or model parameters. Furthermore, there may be multiple ways to achieve any one goal, and it may be difficult to codify a user's preferences before they have seen the available solutions. In this paper we extend simulation models to include plausible sources of uncertainty, and then use a Markov chain Monte Carlo algorithm to sample multiple animations that satisfy constraints. A user can choose the animation they prefer, or applications can take direct advantage of the multiple solutions. Our technique is applicable when a probability can be attached to each animation, with &ldquo;good&rdquo; animations having high probability, and for such cases we provide a definition of physical plausibility for animations. We demonstrate our approach with examples of multi-body rigid-body simulations that satisfy constraints of various kinds, for each case presenting animations that are true to a physical model, are significantly different from each other, and yet still satisfy the constraints.
Automatic parallelization of divide and conquer algorithms
Authors: Radu Rugina, Martin Rinard
Venue: Proceedings of the seventh ACM SIGPLAN symposium on Principles and practice of parallel programming (1999)

Divide and conquer algorithms are a good match for modern parallel machines: they tend to have large amounts of inherent parallelism and they work well with caches and deep memory hierarchies. But these algorithms pose challenging problems for parallelizing compilers. They are usually coded as recursive procedures and often use pointers into dynamically allocated memory blocks and pointer arithmetic. All of these features are incompatible with the analysis algorithms in traditional parallelizing compilers.This paper presents the design and implementation of a compiler that is designed to parallelize divide and conquer algorithms whose subproblems access disjoint regions of dynamically allocated arrays. The foundation of the compiler is a flow-sensitive, context-sensitive, and interprocedural pointer analysis algorithm. A range of symbolic analysis algorithms build on the pointer analysis information to extract symbolic bounds for the memory regions accessed by (potentially recursive) procedures that use pointers and pointer arithmetic. The symbolic bounds information allows the compiler to find procedure calls that can execute in parallel without violating the data dependences. The compiler generates code that executes these calls in parallel. We have used the compiler to parallelize several programs that use divide and conquer algorithms. Our results show that the programs perform well and exhibit good speedup.
Making B+- trees cache conscious in main memory
Authors: Jun Rao, Kenneth A. Ross
Venue: ACM SIGMOD Record (2000)

Previous research has shown that cache behavior is important for main memory index structures. Cache conscious index structures such as Cache Sensitive Search Trees (CSS-Trees) perform lookups much faster than binary search and T-Trees. However, CSS-Trees are designed for decision support workloads with relatively static data. Although B+-Trees are more cache conscious than binary search and T-Trees, their utilization of a cache line is low since half of the space is used to store child pointers. Nevertheless, for applications that require incremental updates, traditional B+-Trees perform well. Our goal is to make B+-Trees as cache conscious as CSS-Trees without increasing their update cost too much. We propose a new indexing technique called &ldquo;Cache Sensitive B+-Trees&rdquo; (CSB+-Trees). It is a variant of B+-Trees that stores all the child nodes of any given node contiguously, and keeps only the address of the first child in each node. The rest of the children can be found by adding an offset to that address. Since only one child pointer is stored explicitly, the utilization of a cache line is high. CSB+-Trees support incremental updates in a way similar to B+-Trees. We also introduce two variants of CSB+-Trees. Segmented CSB+-Trees divide the child nodes into segments. Nodes within the same segment are stored contiguously and only pointers to the beginning of each segment are stored explicitly in each node. Segmented CSB+-Trees can reduce the copying cost when there is a split since only one segment needs to be moved. Full CSB+-Trees preallocate space for the full node group and thus reduce the split cost. Our performance studies show that CSB+-Trees are useful for a wide range of applications.
New Fast Algorithms for Structured Linear Least Squares Problems
Authors: Ming Gu
Venue: SIAM Journal on Matrix Analysis and Applications (1999)

We present new fast algorithms for solving the Toeplitz and the Toeplitz-plus-Hankel least squares problems. These algorithms are based on a new fast algorithm for solving the Cauchy-like least squares problem. We perform an error analysis and provide conditions under which these algorithms are numerically stable. We also develop implementation techniques that significantly reduce the execution time. While no previous fast algorithm is known to be numerically stable for very ill conditioned problems, our numerical results indicate that these new algorithms are efficient and numerically stable for problems ranging from well conditioned to very ill conditioned to numerically singular.
Pseudoknots in RNA secondary structures
Authors: Rune B. Lyngsø, Christian N. S. Pedersen
Venue: Proceedings of the fourth annual international conference on Computational molecular biology (2000)

RNA molecules are sequences of nucleotides that serve as more than mere intermediaries between DNA and proteins, e.g. as catalytic molecules. Computational prediction of RNA secondary structure is among the few structure prediction problems that can be solved satisfactory in polynomial time. Most work has been done to predict structures that do not contain pseudoknots. Allowing pseudoknots introduce modelling and computational problems. In this paper we consider the problem of predicting RNA secondary structure when certain types of pseudoknots are allowed. We first present an algorithm that in time &Ogr;(n5) and space &Ogr;(n3) predicts the secondary structure of an RNA sequence of length n in a model that allows certain kinds of pseudoknots. We then prove that the general problem of predicting RNA secondary structure containing pseudoknots is NP-complete for a large class of reasonable models of pseudoknots.
An Efficient and Scalable Approach for Implementing Fault-Tolerant DSM Architectures
Authors: Christine Morin, Anne-Marie Kermarrec, Michel Banâtre, Alain Gefflaut
Venue: IEEE Transactions on Computers (2000)

Distributed Shared Memory (dsm) architectures are attractive to execute high performance parallel applications. Made up of a large number of components, these architectures have however a high probability of failure. We propose a protocol to tolerate node failures in cache-based dsm architectures. The proposed solution is based on backward error recovery and consists of an extension to the existing coherence protocol to manage data used by processors for the computation and recovery data used for fault tolerance. This approach can be applied to both Cache Only Memory Architectures (coma) and Shared Virtual Memory (svm) systems. The implementation of the protocol in a coma architecture has been evaluated by simulation. The protocol has also been implemented in an svm system on a network of workstations. Both simulation results and measurements show that our solution is efficient and scalable.
Achieving scalability and expressiveness in an Internet-scale event notification service
Authors: Antonio Carzaniga, David S. Rosenblum, Alexander L. Wolf
Venue: Proceedings of the nineteenth annual ACM symposium on Principles of distributed computing (2000)

This paper describes the design of SIENA, an Internet-scale event notification middleware service for distributed event-based applications deployed over wide-area networks. SIENA is responsible for selecting the notifications that are of interest to clients (as expressed in client subscriptions) and then delivering those notifications to the clients via access points. The key design challenge for SIENA is maximizing expressiveness in the selection mechanism without sacrificing scalability of the delivery mechanism. This paper focuses on those aspects of the design of SIENA that fundamentally impact scalability and expressiveness. In particular, we describe SIENA's data model for notifications, the covering relations that formally define the semantics of the data model, the distributed architectures we have studied for SIENA's implementation, and the processing strategies we developed to exploit the covering relations for optimizing the routing of notifications.
The web of system properties: a general view of systems
Authors: Brian Whitworth
Venue: ACM SIGCSE Bulletin (1998)

This paper considers why informed computer predictions are so often wrong. A limited perspective seems to be a factor. It is proposed that a general understanding of the nature of systems is necessary to predict and create the future of information systems. Based on a general definition, a set of system properties is proposed which can be applied equally to human-created and natural systems, i.e. to hardware and software as well as organisms and societies. Assigning values to each property allows a system "web" to be drawn representing its overall performance. The model predicts that Windows will displace DOS, but that electronic mail will not displace paper communication. It is suggested that a balanced view of system properties will not only allow better prediction of future information systems trends, but allow design of information systems which avoid the "revenge" effects common with new technologies.
Walking on Tiles
Authors: Yoram Baram
Venue: Neural Processing Letters (1999)

It is shown that a tiled floor provides continuous stabilizing visual information against stumbling and falling while walking. A steady walk, eyes at a nearly constant height, maintains a certain level of net optical flow in a tile&lsquo;s image. A stumble generates a disturbance in the net flow, which is fed back as a corrective signal to the limbs. This may explain why people with certain motoric disorders, such as those associated with Parkinson&lsquo;s disease, appear to be more comfortable walking on tiled floors than on untiled ones.
Computing with Very Weak Random Sources
Authors: Aravind Srinivasan, David Zuckerman
Venue: SIAM Journal on Computing (1999)

We give an efficient algorithm to extract randomness from a very weak random source using a small additional number t of truly random bits. Our work extends that of Nisan and Zuckerman [ J. Comput. System Sci., 52 (1996), pp. 43--52] in that t remains small even if the entropy rate is well below constant. A key application of this is in running randomized algorithms using such a very weak source of randomness. For any fixed $\gamma > 0$, we show how to simulate RP algorithms in time $n^{O(\log n)}$ using the output of a \ds\ with min-entropy $R^\gamma$. Such a weak random source is asked once for $R$ bits; it outputs an $R$-bit string according to any probability distribution that places probability at most $2^{-R^\gamma}$ on each string. If $\gamma > 1/2$, our simulation also works for BPP; for $\gamma > 1-1/(k+1)$, our simulation takes time $n^{O(\logk n)}$ (log(k) is the logarithm iterated k times). We also give a polynomial-time BPP simulation using Chor--Goldreich sources of min-entropy $R^{\Omega(1)}$, which is optimal. We present applications to time-space tradeoffs, expander constructions, and to the hardness of approximation. Of independent interest is our randomness-efficient Leftover Hash Lemma, a key tool for extracting randomness from weak random sources.
Extending use cases throughout the software lifecycle
Authors: D. Kirner, R. Porter, P. Punniamoorthy, M. Schuh, D. Shoup, S. Tindall, D. Umphress
Venue: ACM SIGSOFT Software Engineering Notes (1999)

The relevance of use cases throughout the software development life cycle is considered in the context of an actual project. Extensions, called behavior case and test cases are proposed to address design and testing activities.
Validation and test generation for oscillatory noise in VLSI interconnects
Authors: Arani Sinha, Sandeep K. Gupta, Melvin A. Breuer
Venue: Proceedings of the 1999 IEEE/ACM international conference on Computer-aided design (1999)

Inductance of on-chip interconnects gives rise to signal overshoots and undershoots that can cause logic errors. By considering technology trends, we show that in 0.13 &mgr;m technology such noise in local interconnects embedded in combinational logic can exceed the threshold voltage. We show the impact of such noise on different kinds of circuits. The magnitude of this noise can increase due to process variations. We present an algorithm for generating vectors for validation and manufacturing test to detect logic-value errors caused by inductance induced oscillation. To faciliate the vector generation method, we have derived analytical expressions, as functions of rise and fall times for (i) the magnitude of overshoots and undershoots, and (ii) the settling time, i.e., the time required for the circuit response to settle to a bound close to the final value.
Reconfigurable caches and their application to media processing
Authors: Parthasarathy Ranganathan, Sarita Adve, Norman P. Jouppi
Venue: ACM SIGARCH Computer Architecture News (2000)

High performance general-purpose processors are increasingly being used for a variety of application domains - scientific, engineering, databases, and more recently, media processing. It is therefore important to ensure that architectural features that use a significant fraction of the on-chip transistors are applicable across these different domains. For example, current processor designs often devote the largest fraction of on-chip transistors (up to 80%) to caches. Many workloads, however, do not make effective use of large caches; e.g., media processing workloads which often have streaming data access patterns and large working sets. This paper proposes a new reconfigurable cache design. This design enables the cache SRAM arrays to be dynamically divided into multiple partitions that can be used for different processor activities. These activities can benefit applications that would otherwise not use the storage allocated to large conventional caches. Our design involves relatively few modifications to conventional cache design, and analysis using a modification of the CACTI analytical model shows a small impact on cache access time. We evaluate one representative use of reconfigurable caches - instruction reuse for media processing. We find this use gives IPC improvements ranging from 1.04X to 1.20X in simulation across eight media processing benchmarks.
Mastrovito Multiplier for All Trinomials
Authors: B. Sunar, Ç. K. Koç
Venue: IEEE Transactions on Computers (1999)

An efficient algorithm for the multiplication in $GF(2^m)$ was introduced by Mastrovito. The space complexity of the Mastrovito multiplier for the irreducible trinomial $x^m+x+1$ was given as $m^2-1$ XOR and $m^2$ AND gates. In this paper, we describe an architecture based on a new formulation of the multiplication matrix and show that the Mastrovito multiplier for the generating trinomial $x^m+x^n+1$, where $m \not=2n$, also requires $m^2-1$ XOR and $m^2$ AND gates. However, $m^2-m/2$ XOR gates are sufficient when the generating trinomial is of the form $x^m+x^{m/2}+1$ for an even $m$. We also calculate the time complexity of the proposed Mastrovito multiplier and give design examples for the irreducible trinomials $x^7+x^4+1$ and $x^6+x^3+1$.
Techniques for improving the efficiency of sequential circuit test generation
Authors: Xijiang Lin, Irith Pomeranz, Sudhakar M. Reddy
Venue: Proceedings of the 1999 IEEE/ACM international conference on Computer-aided design (1999)

New techniques are presented in this paper to improve the efficiency of a test generation procedure for synchronous sequential circuits. These techniques aid the test generation procedure by reducing the search space, carrying out non-chronological backtracking, and reusing the test generation effort. They have been integrated into an existing sequential test generation system MIX to constitute a new system, named MIX-PLUS. The experimental results for the ISCAS-89 and ADDENDUM-93 benchmark circuits demonstrate the effectiveness of these techniques in improving the fault coverage and test generation efficiency.
Computer-Mediated Communication and Majority Influence
Authors: Bernard C. Y. Tan, Kwok-Kee Wei, Richard T. Watson, Danial L. Clapper, Ephraim R. Mclean
Venue: Management Science (1998)

Strong majority influence can potentially harm organizational decisions by causing decision makers to engage in groupthink. This study examines whether and how computer-mediated communication (CMC) can reduce majority influence and thereby enhance the quality of decisions in some situations. To measure the impact of CMC on majority influence, three settings (unsupported, face-to-face CMC, and dispersed CMC) were compared. Matching laboratory experiments were carried out in an individualistic (the US) and a collectivistic culture (Singapore) to determine how the impact of CMC might be moderated by national culture. An intellective and a preference task were used to see whether the impact of CMC might be moderated by task type. The results showed that the impact of CMC on majority influence was contingent upon national culture. In the individualistic culture, majority influence was stronger in the unsupported setting than the face-to-face CMC and dispersed CMC settings. In the collectivistic culture, there were no corresponding differences. The results also revealed that the impact of CMC on majority influence was not moderated by task type. Instead, task type had a direct impact on majority influence. Regardless of the setting involved, majority influence was stronger with the preference than the intellective task. Besides demonstrating how cultural factors may moderate the impact of CMC, this study raises the broader issue of cultural relativism in current knowledge on CMC.
Threshold-Based Mechanisms to Discriminate Transient from Intermittent Faults
Authors: Andrea Bondavalli, Silvano Chiaradonna, Felicita Di Giandomenico, Fabrizio Grandoni
Venue: IEEE Transactions on Computers (2000)

This paper presents a class of count-and-threshold mechanisms, collectively named $\alpha$-count, which are able to discriminate between transient faults and intermittent faults in computing systems. For many years, commercial systems have been using transient fault discrimination via threshold-based techniques. We aim to contribute to the utility of count-and-threshold schemes, by exploring their effects on the system. We adopt a mathematically defined structure, which is simple enough to analyze by standard tools. $\alpha$-count is equipped with internal parameters that can be tuned to suit environmental variables (such as transient fault rate, intermittent fault occurrence patterns). We carried out an extensive behavior analysis for two versions of the count-and-threshold scheme, assuming, first, exponentially distributed fault occurrencies and, then, more realistic fault patterns.
A software synthesis tool for distributed embedded system design
Authors: D.-I. Kang, R. Gerber, L. Golubchik, J. K. Hollingsworth, M. Saksena
Venue: Proceedings of the ACM SIGPLAN 1999 workshop on Languages, compilers, and tools for embedded systems (1999)

We present a design tool for automated synthesis of embedded systems on distributed COTS-based platforms. Our synthesis tool consists of (1) a graphical user interface for input of software layouts, which maps tasks to resources and (2) a constraints solving engine, which allocates local resources to tasks, all with the goal of meeting specified performance criteria. Our tool differs from previous work in that it allows (a) use of stochastic (rather than worst-case) models of resource usage and (b) resource sharing among components. Our approach uses analytical approximate solutions for quick estimates of the desired performance measures. These estimates permit an efficient search of the possible design space. Once candidate designs are determined, they are validated through a simulation model. We demonstrate the efficiency and robustness of this tool on a synthetic aperture radar benchmark.
Adaptive Mesh Refinement and Front-Tracking for Shear Bands in an Antiplane Shear Model
Authors: F. Xabier Garaizar, John Trangenstein
Venue: SIAM Journal on Scientific Computing (1998)

In this paper we describe a numerical algorithm for the study of shear-band formation and growth in a two-dimensional antiplane shear of granular materials. The algorithm combines front-tracking techniques and adaptive mesh refinement. Tracking provides a more careful evolution of the band when coupled with special techniques to advance the ends of the shear band in the presence of a loss of hyperbolicity. The adaptive mesh refinement allows the computational effort to be concentrated in important areas of the deformation, such as the shear band and the elastic relief wave. The main challenges are the problems related to shear bands that extend across several grid patches and the effects that a nonhyperbolic growth rate of the shear bands has in the refinement process. We give examples of the success of the algorithm for various levels of refinement.
A New Model of Computation for Learning Vision Modules from Examples
Authors: Rhys A. Newman
Venue: Journal of Mathematical Imaging and Vision (1999)

This paper addresses an important class of mimicry problems, where the goal is to construct a computer program which is functionally equivalent to an observed behaviour. Computer vision research can be considered such a challenge, where a researcher attempts to impart human visual abilities to a computer. Unfortunately this has proved a difficult task, not least because our vision processes occur mostly at a subconscious level. It is therefore useful to study the general mimicry problem in order to develop tools which may assist computer vision research.This paper formalises a mimicry problem as one in which a computer learning system (L) constructs a solution from a given program structure (i.e. template or outline) by posing questions to an Oracle. The latter is an entity which, when given an input value, produces the corresponding output of the function which is to be mimicked.In order to define a program&lsquo;s structure, particularly one which can be extracted from any computer program automatically, a new model of computation is developed. Based on this a fast algorithm which determines the best questions to pose to the Oracle is then described. Thus L relieves the human programmer of the difficulties faced in choosing the examples from which to learn. This is important because a human programmer might inadvertently choose biased, redundant or otherwise unhelpful examples. Results are shown which demonstrate the utility of a complete learning system (L) based on this work.This paper represents background theory and initial algorithms which further work will extend into powerful automatic learning systems, examples of which are found in [36] and [38].