ppxscal/embedding_network huggingface dataset:
Hierarchical timing analysis using conditional delays
Authors: Hakan Yalcin, John P. Hayes
Venue: Proceedings of the 1995 IEEE/ACM international conference on Computer-aided design (1995)

We present a novel method to perform timing analysis of hierarchical circuits. It is based on the representation of circuit modules by conditional delay matrices (CDMs) which combine module delays with event propagation conditions. The CDM model is independent of module complexity and allows automatic identification of false paths. We exploit hierarchy information to perform efficient delay computation. The effectiveness of the method is demonstrated on a high-level model of the ISCAS-85 circuit c6288, which is difficult to analyze using traditional approaches. The method has been implemented in a symbolic timing analysis program called CAT. The application of CAT to carry-skip adders shows that hierarchical timing analysis is faster by an order of magnitude than gate-level analysis.
Search Problems in the Decision Tree Model
Authors: Laszlo Lovasz, Moni Naor, Ilan Newman, Avi Wigderson
Venue: SIAM Journal on Discrete Mathematics (1995)

The relative power of determinism, randomness, and nondeterminism for search problems in the Boolean decision tree model is studied. It is shown that the gaps between the nondeterministic, the randomized, and the deterministic complexities can be arbitrarily large for search problems. An interesting connection of this model to the complexity of resolution proofs is also mentioned.
Reducing multidatabase query response time by tree balancing
Authors: Weimin Du, Ming-Chien Shan, Umeshwar Dayal
Venue: Proceedings of the 1995 ACM SIGMOD international conference on Management of data (1995)

Execution of multidatabase queries differs from that of traditional queries in that sort merge and hash joins are more often favored, as nested loop join requires repeated accesses to external data sources. As a consequence, left deep join trees obtained by traditional (e.g., System-R style) optimizers for multidatabase queries are often suboptimal, with respect to response time, due to the long delay for a sort merge (or hash) join node to produce its last result after the subordinate join node did. In this paper, we present an optimization strategy that first produces an optimal left deep join tree and then reduces the response time using simple tree transformations. This strategy has the advantages of guaranteed minimum total resource usage, improved response time, and low optimization overhead. We describe a class of basic transformations that is the cornerstone of our approach. Then we present algorithms that effectively apply basic transformations to balance a left deep join tree, and discuss how the technique can be incorporated into existing query optimizers.
On the Removal of Boundary Errors Caused by Runge--Kutta Integration of Nonlinear Partial Differential Equations
Authors: Saul Abarbanel, David Gottlieb, Mark H. Carpenter
Venue: SIAM Journal on Scientific Computing (1996)

The temporal integration of hyperbolic partial differential equations (PDEs) has been shown to lead sometimes to the deterioration of accuracy of the solution because of boundary conditions. A procedure for removal of this error in the linear case has been established previously.In this paper we consider hyperbolic PDEs (linear and nonlinear) whose boundary treatment is accomplished via the simultaneous approximation term (SAT) procedure. A methodology is presented for recovery of the full order of accuracy and has been applied to the case of a fourth-order explicit finite-difference scheme.
CYC: a large-scale investment in knowledge infrastructure
Authors: Douglas B. Lenat
Venue: Communications of the ACM (1995)

Since 1984, a person-century of effort has gone into building CYC, a universal schema of roughly 105 general concepts spanning human reality. Most of the time has been spent codifying knowledge about these concepts; approximately 106 commonsense axioms have been handcrafted for and entered into CYC's knowledge base, and millions more have been inferred and cached by CYC. This article examines the fundamental assumptions of doing such a large-scale project, reviews the technical lessons learned by the developers, and surveys the range of applications that are or soon will be enabled by the technology.
Relative debugging and its application to the development of large numerical models
Authors: David Abramson, Ian Foster, John Michalakes, Rok Sosic
Venue: Proceedings of the 1995 ACM/IEEE conference on Supercomputing (CDROM) (1995)

Because large scientific codes are rarely static objects, developers are often faced with the tedious task of accounting for discrepancies between new and old versions. In this paper, we describe a new technique called relative debugging that addresses this problem by automating the process of comparing a modified code against a correct reference code. We examine the utility of the relative debugging technique by applying a relative debugger called Guard to a range of debugging problems in a large atmospheric circulation model. Our experience confirms the effectiveness of the approach. Using Guard, we are able to validate a new sequential version of the atmospheric model, and to identify the source of a significant discrepancy in a parallel version in a short period of time.
Bounded-skew clock and Steiner routing under Elmore delay
Authors: Jason Cong, Andrew B. Kahng, Cheng-Kok Koh, C.-W. Albert Tsao
Venue: Proceedings of the 1995 IEEE/ACM international conference on Computer-aided design (1995)

We study the minimum-cost bounded-skew routing tree problem under the Elmore delay model. We present two approaches to construct bounded-skew routing trees: (i) the Boundary Merging and Embedding (BME) method which utilizes merging points that are restricted to the boundaries of merging regions, and (ii) the Interior Merging and Embedding (IME) algorithm which employs a sampling strategy and dynamic programming to consider merging points that are interior to, rather than on the boundary of, the merging regions. Our new algorithms allow accurate control of Elmore delay skew, and show the utility of merging points inside merging regions.
Approximating grammar probabilities: solution of a conjecture
Authors: R. Chaudhuri, A. N. V. Rao
Venue: Journal of the ACM (JACM) (1986)

It is proved that the production probabilities of a probabilistic context-free grammar may be obtained as the limit of the estimates inferred from an increasing sequence of randomly drawn samples from the language generated by the grammar.
How Far 3D Shapes Can Be Understood from 2D Silhouettes
Authors: Aldo Laurentini
Venue: IEEE Transactions on Pattern Analysis and Machine Intelligence (1995)

Each 2D silhouette of a 3D unknown object O constrains O inside the volume obtained by back-projecting the silhouette from the corresponding viewpoint. A set of silhouettes specifies a boundary volume R, obtained by intersecting the volumes due to each silhouette. R more or less closely approximates O, depending on the viewpoints and the object itself. This approach to the reconstruction of 3D objects is usually referred to as volume intersection. This correspondence addresses the problem of inferring the shape of the unknown object O from the reconstructed object R. For doing this, we divide the points of the surface of R into hard points, which belong to the surface of any possible object originating R, and soft points, which may or may not belong to O. We consider two cases: In the first case R is the closest approximation of O which can be obtained from its silhouettes, i.e., its visual hull; in the second case, R is a generic reconstructed object. In both cases we supply necessary and sufficient conditions for a point to be hard and give rules for computing the hard surfaces.
Two Packet Routing Algorithms on a Mesh-Connected Computer
Authors: Qian-Ping Gu, Jun Gu
Venue: IEEE Transactions on Parallel and Distributed Systems (1995)

In this paper, we give two algorithms for the 1-1 routing problems on a mesh-connected computer. The first algorithm, with queue size 28, solves the 1-1 routing problem on an $n\times n$ mesh-connected computer in $2n+O(1)$ steps. This improves the previous queue size of $75$. The second algorithm solves the 1-1 routing problem in $2n-2$ steps with queue size $12t_s/s$ where $t_s$ is the time for sorting an $s\times s$ mesh into a row major order for all $s\geq 1$. This result improves the previous queue size $18.67t_s/s$.Index Terms¿Parallel algorithms, mesh-connected computer, packet routing, queue size, time complexity.
The role of simulation in operational planning and control of flexible machining cells
Authors: Shahin Rahimifard, Stephen T. Newman
Venue: Proceedings of the 27th conference on Winter simulation (1995)

The use of simulation as a solution to the operational planning and control problems of flexible machining cells is now well established. This paper describes the role of simulation models as: a decision support tool, a scheduler and as an aid to develop appropriate control procedures. To illustrate the ideas presented a novel framework for the simultaneous management and control of parts, fixtures and cutting tools is outlined which is termed multi-flow control. Three simulation models have been designed and implemented to carry out specific tasks within this framework. These models and their respective functionality are also described in this paper.
Joint integration of the object-oriented paradigm at Amarillo College and Texas Tech University
Authors: Donald J. Bagert, H. Paul Haiduk
Venue: 3C ON-LINE (1995)

The current debate over whether and where to include the object-oriented paradigm in undergraduate computing science curricula is strikingly similar to another debate not yet finished. Anyone who has been involved in CS curricula for over ten years will recall that we are still sometimes debating where to first present concepts of procedural and functional abstraction, although hardly anyone debates that we should not do so at all. Thus, there is a real sense of deja vu with respect to the current debate over the Object-Oriented Paradigm (OOP). That is, virtually everyone feels that it should be included, but there is still a wide variety of opinions as to where and how it should be done. This paper discusses how the teaching of the object-oriented paradigm has evolved over the last several years in the two-year program at Amarillo College and at the four-year undergraduate program at Texas Tech University, which are 120 miles apart.
Computing the MDMT decomposition
Authors: Linda Kaufman
Venue: ACM Transactions on Mathematical Software (TOMS) (1995)

The MDMT factorization of an n&times;n symmetric indefinite matrix A can be used to solve a linear system with A as the coefficient matrix. This factorization can be computed efficiently using an algorithm given in 1977 by Bunch and Kaufman. The LAPACK project has been implementing block versions of well-known algorithms for solving dense linear systems and eigenvalue problems. The block version of the MDMT decomposition algorithm in LAPACK requires the user to specify a block size b by supplying an n&times;b scratch array. It then makes (n/b&minus;2)2/2 invocations of a matrix-matrix product subroutine with one matrix no larger than b&times;b, n2/(2b)&minus;b invocations of a matrix-vector product routine with a matrix no larger than b&times;b, and between n&minus;n/b and 2(n&minus;n/b) invocations of a matrix-vector product routine with matrices with less than b columns. Because the user can query LAPACK about an optimal block size, our concern is focused on users who cannot change the amount of available scratch space or who neglect to use this facility and are unaware of a performance degradation with small block sizes. This article suggests two alternative algorithms. The first is a block algorithm requiring b&times;b scratch space and is about 5% slower than LAPACK's current block algorithm with large b. The user does not have to specify the block size. The second algorithm is a rejuvenation of an old implementation of the MDMT decomposition algorithm that requires n matrix-vector products. The performance of the various algorithms on a specific machine is dependent on the manufacturer's implementation of the different basic linear algebra subroutines that they each invoke. Our data indicate that on the Cray Y-MP, Alliant, and Convex the time for the rejuvenated algorithm is either less than or within 10% of that of LAPACK's block algorithm with large b.
Non-repudiation with mandatory proof of receipt
Authors: Tom Coffey, Puneet Saidha
Venue: ACM SIGCOMM Computer Communication Review (1996)

Non-repudiation allows an exchange of data between two principals in such a manner that the principals cannot subsequently deny their participation in the exchange. Current non-repudiation schemes, while providing a mandatory proof of origin service, generally provide only discretionary proof of receipt since it is difficult to enforce the return of the proof of receipt by the recipient.In this paper a new scheme for achieving mandatory mutual non-repudiation is proposed, encompassing both mandatory proof of origin and mandatory proof of receipt. The fundamental feature of the scheme is that the proofs of origin and receipt are not exchanged until both principals have submitted their digitally signed evidence to a trusted third party intermediary. This ensures that if the non-repudiation protocol is not completed, neither principal can gain from the exchange. An added advantage is that the process of dispute arbitration is considerably simplified since a small number of rules are required to decide whether an alleged data exchange took place.
Optimal incremental parsing
Authors: J.-M. Larchevêque
Venue: ACM Transactions on Programming Languages and Systems (TOPLAS) (1995)

This communication sets the problem of incremental parsing in the context of a complete incremental compiling system. It turns out that, according to the incrementally paradigm of the attribute evaluator and data-flow analyzer to be used, two definitions of optimal incrementality in a parser are possible. Algorithms for achieving both forms of optimality are given, both of them based on ordinary LALR(1) parse tables. Optimality and correctness proofs, which are merely outlined in this communication, are made intuitive thanks to the concept of a well-formed list of threaded trees, a natural extension of the concept of threaded tree found in earlier works on incremental parsing.
Ambitious evaluation: a new reading of an old issue
Authors: Kent M. Pitman
Venue: ACM SIGPLAN Lisp Pointers (1995)

Much has been written about Lazy Evaluation in Lisp---less about the other end of the spectrum---Ambitious Evaluation. Ambition is a very subjective concept, though, and if you have some preconceived idea of what you think an Ambitious Evaluator might be about, you might want to set it aside for a few minutes because this probably isn't going to be what you expect.
The quickhull algorithm for convex hulls
Authors: C. Bradford Barber, David P. Dobkin, Hannu Huhdanpaa
Venue: ACM Transactions on Mathematical Software (TOMS) (1996)

The convex hull of a set of points is the smallest convex set that contains the points. This article presents a practial convex hull algorithm that combines the two-dimensional Quickhull algorithm with the general-dimension Beneath-Beyond Algorithm. It is similar to the randomized, incremental algorithms for convex hull and delaunay triangulation. We provide empirical evidence that the algorithm runs faster when the input contains nonextreme points and that it used less memory. computational geometry algorithms have traditionally assumed that input sets are well behaved. When an algorithm is implemented with floating-point arithmetic, this assumption can lead to serous errors. We briefly describe a solution to this problem when computing the convex hull in two, three, or four dimensions. The output is a set of &ldquo;thick&rdquo; facets that contain all possible exact convex hulls of the input. A variation is effective in five or more dimensions.
Generating binary trees using rotations
Authors: David Zerling
Venue: Journal of the ACM (JACM) (1985)

A new algorithm that, for the first time, exploits the rotational geometry of binary trees is developed in order to allow for the lexicographic generation of computer representations of these trees in average time O(1) per tree. &ldquo;Rotation&rdquo; codewords for these trees (in average time O(1) per tree) are also generated. It is shown how these codewords relate to lattice paths, and, using this relationship, that n(n - 1)/(n + 2) is the average number of rotations needed to generate a binary tree on n nodes. Finally, a necessary and sufficient condition that a codeword represent a full binary tree (each node has 0 or 2 sons) on n = 2m + 1 nodes is given and how to contract this codeword to obtain the codeword for the binary tree on m nodes for which this full tree is the extended binary tree is shown.
A software infrastructure to support introductory computer science courses
Authors: Kenneth A. Reek
Venue: Proceedings of the twenty-seventh SIGCSE technical symposium on Computer science education (1996)

This paper describes the software developed to support the first two years of the Computer Science curriculum at the Rochester Institute of Technology. The system supports student retrieval of files and data; on-line submission with immediate, automated testing and archiving of student work; and assists in grading the work and the associated record keeping.
A decomposition of multidimensional point sets with applications to k-nearest-neighbors and n-body potential fields
Authors: Paul B. Callahan, S. Rao Kosaraju
Venue: Journal of the ACM (JACM) (1995)

We define the notion of a well-separated pair decomposition of points in d-dimensional space. We then develop efficient sequential and parallel algorithms for computing such a decomposition. We apply the resulting decomposition to the efficient computation of k-nearest neighbors and n-body potential fields.
Visual metaphors for interacting with databases
Authors: Tiziana Catarci, Maria F. Costabile, Maristella Matera
Venue: ACM SIGCHI Bulletin (1995)

The need for better human-computer interaction (HCI) has been widely recognized and discussed, even in the database area. It is generally accepted that the quality of the interaction mainly depends on the interface characteristics. How does one recognize "good" interfaces? The use of a suitable metaphor is crucial. Unfortunately, to put it as a metaphor, speaking about metaphors in HCI is like walking on a slippery floor.We would like to come up with a definition of metaphor that is specific to the particular needs of the database area, and, of course, of the database users. Thus, we will highlight some peculiarities of the database interaction. The following considerations should constitute a basis towards a formal approach for the construction of effective metaphors for interacting with databases.
Architectural principles and techniques for distributed multimedia application support in operating systems
Authors: Geoff Coulson, Gordon Blair
Venue: ACM SIGOPS Operating Systems Review (1995)

We propose some architectural principles we have found useful for the support of continuous media applications in a microkernel environment. In particular, we discuss i) the principle of upcall-driven application structuring whereby communications events are system rather than application initiated, ii) the principle of split-level system structuring whereby key system functions are carried out co-operatively between kernel and user level components and iii) the principle of decoupling of control transfer and data transfer. Under these general headings a number of particular mechanisms and techniques are discussed. Our suggestions arise from experiences in implementing a Chorus based real-time and multimedia support infrastructure within the SUMO project.
MONSTER&mdash;the ghost in the connection machine: modularity of neural systems in theoretical evolutionary research
Authors: Nigel Snoad, Terry Bossomaier
Venue: Proceedings of the 1995 ACM/IEEE conference on Supercomputing (CDROM) (1995)

Both genetic algorithms (GAs) and artificial neural networks (ANNs) (connectionist learning models) are effective generalisations of successful biological techniques to the artificial realm. Both techniques are inherently parallel and seem ideal for implementation on the current generation of parallel supercomputers. We consider how the two techniques complement each other and how combining them (i.e. evolving artificial neural networks with a genetic algorithm), may give insights into the evolution of structure and modularity in biological brains. The incorporation of evolutionary and modularity concepts into artificial systems has the potential to decrease the development time of ANNs for specific image and information processing applications. General considerations when genetically encoding ANNs are discussed, and a new encoding method developed, which has the potential to simplify the generation of complex modular networks. The implementation of this technique on a CM-5 parallel supercomputer raises many practical and theoretical questions in the application and use of evolutionary models with artificial neural networks.
Heraclitus: elevating deltas to be first-class citizens in a database programming language
Authors: Shahram Ghandeharizadeh, Richard Hull, Dean Jacobs
Venue: ACM Transactions on Database Systems (TODS) (1996)

Traditional database systems provide a user with the ability to query and manipulate one database state, namely the current database state. However, in several emerging applications, the ability to analyze &ldquo;what-if&rdquo; scenarios in order to reason about the impact of an update (before committing that update) is of paramount importance. Example applications include hypothetical database access, active database management systems, and version management, to name a few. The central thesis of the Heraclitus paradigm is to provide flexible support for applications such as these by elevating deltas, which represent updates proposed against the current database state, to be first-class citizens. Heraclitus[Alg,C] is a database programming language that extends C to incorporate the relational algebra and deltas. Operators are provided that enable the programmer to explicitly construct, combine, and access deltas. Most interesting is the when operator, that supports hypothetical access to a delta: the expression E when &sgr; yields the value that side effect free expression E would have if the value of delta expression &sgr; were applied to the current database state. This article presents a broad overview of the philosophy underlying the Heraclitus paradigm, and describes the design and prototype implementation of Heraclitus[Alg, C]. A model-independent formalism for the Heraclitus paradigm is also presented. To illustrate the utility of Heraclitus, the article presents an in-depth discussion of how Heraclitus[Alg, C] can be used to specify, and thereby implement, a wide range of execution models for rule application in active databases; this includes both prominent execution models presented in the literature, and more recent &ldquo;customized&rdquo; execution models with novel features.
Coordination in software development
Authors: Robert E. Kraut, Lynn A. Streeter
Venue: Communications of the ACM (1995)

Since its inception, the software industry has been in crisis. As Blazer noted 20 years ago, &ldquo;[Software] is unreliable, delivered late, unresponsive to change, inefficient, and expensive &hellip; and has been for the past 20 years&rdquo; [4]. In a survey of software contractors and government contract officers, over half of the respondents believed that calendar overruns, cost overruns, code that required in-house modifications before being usable, and code that was difficult to modify were common problems in the software projects they supervised [22]. Even today, problems with software systems are common and highly-publicized occurrences.