ppxscal/embedding_network huggingface dataset:
BeSS object storage manager: architecture overview
Authors: Alexandros Biliris, Euthimios Panagos
Venue: ACM SIGMOD Record (1996)

BeSS is a high performance, memory-mapped object storage manager offering distributed transaction management facilities and extensible support for persistence. In this paper, we present an overview of the peer-to-peer architecture of BeSS, and we discuss issues related to space management, inter-object references, database corruption, operation modes, cache replacement, and transaction management.
Rapid bushy join-order optimization with Cartesian products
Authors: Bennet Vance, David Maier
Venue: ACM SIGMOD Record (1996)

Query optimizers often limit the search space for join orderings, for example by excluding Cartesian products in subplans or by restricting plan trees to left-deep vines. Such exclusions are widely assumed to reduce optimization effort while minimally affecting plan quality. However, we show that searching the complete space of plans is more affordable than has been previously recognized, and that the common exclusions may be of little benefit.We start by presenting a Cartesian product optimizer that requires at most a few seconds of workstation time to search the space of bushy plans for products of up to 15 relations. Building on this result, we present a join-order optimizer that achieves a similar level of performance, and retains the ability to include Cartesian products in subplans wherever appropriate. The main contribution of the paper is in fully separating join-order enumeration from predicate analysis, and in showing that the former problem in particular can be solved swiftly by novel implementation techniques. A secondary contribution is to initiate a systematic approach to the benchmarking of join-order optimization, which we apply to the evaluation of our method.
Temporal conditions and integrity constraints in active database systems
Authors: A. Prasad Sistla, Ouri Wolfson
Venue: Proceedings of the 1995 ACM SIGMOD international conference on Management of data (1995)

In this paper, we present a unified formalism, based on Past Temporal Logic, for specifying conditions and events in the rules for active database system. This language permits specification of many time varying properties of database systems. It also permits specification of temporal aggregates. We present an efficient incremental algorithm for detecting conditions specified in this language. The given algorithm, for a subclass of the logic, was implemented on top of Sybase.
Local and global optimization algorithms for generalized learning automata
Authors: V. V. Phansalkar, M. A. L. Thathachar
Venue: Neural Computation (1995)

This paper analyzes the long-term behavior of the REINFORCE and related algorithms (Williams 1986, 1988, 1992) for generalized learning automata (Narendra and Thathachar 1989) for the associative reinforcement learning problem (Barto and Anandan 1985). The learning system considered here is a feedforward connectionist network of generalized learning automata units. We show that REINFORCE is a gradient ascent algorithm but can exhibit unbounded behavior. A modified version of this algorithm, based on constrained optimization techniques, is suggested to overcome this disadvantage. The modified algorithm is shown to exhibit local optimization properties. A global version of the algorithm, based on constant temperature heat bath techniques, is also described and shown to converge to the global maximum. All algorithms are analyzed using weak convergence techniques.
Declarative Bias for Specific-to-General ILP Systems
Authors: Hilde Adé, Luc De Raedt, Maurice Bruynooghe
Venue: Machine Learning (1995)

A comparative study is presented of language biases employed in specific-to-general learning systems within the Inductive Logic Programming (ILP) paradigm. More specifically, we focus on the biases employed in three well known systems: CLINT, GOLEM and ITOU, and evaluate both conceptually and empirically their strengths and weaknesses. The evaluation is carried out within the generic framework of the NINA system, in which bias is a parameter. Two different types of biases are considered: syntactic bias, which defines the set of well-formed clauses, and semantic bias, which imposes restrictions on the behaviour of hypotheses or clauses. NINA is also able to shift its bias (within a predefined series of biases), whenever its current bias is insufficient for finding complete and consistent concept definitions. Furthermore, a new formalism for specifying the syntactic bias of inductive logic programming systems is introduced.
Future joint warfare analysis model designs
Authors: William G. Lese,  Jr., Jim Metzger
Venue: Proceedings of the 27th conference on Winter simulation (1995)

The Joint Warfare System (JWARS) is a state-of-the-art simulation of joint warfare for analysis, to be developed as one component of the Joint Analytic Model Improvement Program recently approved by the Deputy Secretary of Defense. This paper describes the rationale, objectives, management, approach and status of JWARS.
Controlling application grain size on a network of workstations
Authors: Bruce S. Siegell, Peter A. Steenkiste
Venue: Proceedings of the 1995 ACM/IEEE conference on Supercomputing (CDROM) (1995)

An important challenge in the area of distributed computing is to automate the selection of the parameters that control the distributed computation. A performance-critical parameter is the grain size of the computation, i.e., the interval between successive synchronization points in the application. This parameter is hard to select since it depends both on compile time (loop structure and data dependences, computational complexity) and run time components (speed of compute nodes and network). On networks of workstations that are shared with other users, the run-time parameters can change over time. As a result, it is also necessary to consider the interactions with dynamic load balancing, which is needed to achieve good performance in this environment. In this paper we present a method for automatically selecting the grain size of the computation consisting of nested DO loops. The method is based on close cooperation between the compiler and the runtime system. We evaluate the method using both simulation and measurements for an implementation on the Nectar multicomputer.
The Group Inverse Associated with an Irreducible Periodic Nonnegative Matrix
Authors: Steve Kirkland
Venue: SIAM Journal on Matrix Analysis and Applications (1995)

Suppose that $\bf M$ is an irreducible stochastic matrix with period $d\geq 2$. The canonical form for $\bf M$ that exhibits its periodic structure generates a natural partitioning of $\bf M$, which in turn generates a partitioning of $({\bf I} - {\bf M})^\#$, the group generalized inverse of ${\bf I} - {\bf M}$. We derive a formula for the blocks in the partitioned form of $({\bf I} - {\bf M})^#$, discuss possible sign patterns of $({\bf I} - {\bf M})^\#$, and use the partitioned formula to obtain information about the Markov chain associated with $\bf M}.
A comparison of three strategies for computing letter oriented, minimal perfect hashing functions
Authors: John A. Trono
Venue: ACM SIGPLAN Notices (1995)

This paper will discuss improvements to Cichelli's method for computing the set of weights used for minimal perfect hashing functions[1]. The major modifications investigated here pertain to adding a "MOD number_of_keys" operation to the hashing function, and to the removal of unnecessary backtracking due to "guaranteed collisions".
Closure analysis in constraint form
Authors: Jens Palsberg
Venue: ACM Transactions on Programming Languages and Systems (TOPLAS) (1995)

Flow analyses of untyped higher-order functional programs have in the past decade been presented by Ayers, Bondorf, Consel, Jones, Heintze, Sestoft, Shivers, Steckler, Wand, and others. The analyses are usually defined as abstract interpretations and are used for rather different tasks such as type recovery, globalization, and binding-time analysis. The analyses all contain a global closure analysis that computes information about higher-order control-flow. Sestoft proved in 1989 and 1991 that closure analysis is correct with respect to call-by-name and call-by-value semantics, but it remained open if correctness holds for arbitrary beta-reduction.This article answers the question; both closure analysis and others are correct with respect to arbitrary beta-reduction. We also prove a subject-reduction result: closure information is still valid after beta-reduction. The core of our proof technique is to define closure analysis using a constraint system. The constraint system is equivalent to the closure analysis of Bondorf, which in turn is based on Sestoft's.
MASSIVE: a collaborative virtual environment for teleconferencing
Authors: Chris Greenhalgh, Steven Benford
Venue: ACM Transactions on Computer-Human Interaction (TOCHI) (1995)

We describe a prototype virtual reality teleconferencing system called MASSIVE which has been developed as part of our on-going research into collaborative virtual environments. This system allows multiple users to communicate using arbitrary combinations of audio, graphics, and text media over local and wide area networks. Communication is controlled by a so-called spatial model of interaction so that one user's perception of another user is sensitive to their relative positions and orientations. The key concept in this spatial model is the (quantitative) awareness which one object has of another. This is controlled by the observing object's focus and the observed object's nimbus, which describe regions of interest and projection, respectively. Each object's aura defines the total region within which it interacts. This is applied independently in each medium. The system (and the spatial model which it implements) is intended to provide a flexible and natural environment for the spatial mediation of conversation. The model also provides a basis for scaling to relatively large numbers of users. Our design goals include supporting heterogeneity, scalability, spatial mediation, balance of power, and multiple concurrent meetings; MASSIVE meets all of these goals. Our initial experiences show the importance of audio in collaborative VR, and they raise issues about field of view for graphical users, speed of navigation, quality of embodiment, varying perceptions of space, and scalability.
Functional test generation for delay faults in combinational circuits
Authors: Irith Pomeranz, Sudhakar M. Reddy
Venue: Proceedings of the 1995 IEEE/ACM international conference on Computer-aided design (1995)

Abstract: We propose a functional fault model for delay faults in combinational circuits and describe a functional test generation procedure based on this model. The proposed method is most suitable when a gate-level description of the circuit-under-test, necessary for employing existing gate-level delay fault test generators, is not available. It is also suitable for generating tests in early design stages of a circuit, before a gate-level implementation is selected. It can also potentially be employed to supplement conventional test generators for gate-level circuits to reduce the cost of branch and bound strategies. A parameter called /spl Delta/ is used to control the number of functional faults targeted and thus the number of tests generated. If /spl Delta/ is unlimited, the functional test set detects every robustly testable path delay fault in any gate-level implementation of the given function. An appropriate subset of tests can be selected once the implementation is known. The test sets generated for various values of /spl Delta/ are fault simulated on gate-level realizations to demonstrate their effectiveness.
Case tool integration and utilization within the joint theater level simulation (JTLS)
Authors: Robert L. Wittman,  Jr.
Venue: Proceedings of the 27th conference on Winter simulation (1995)

Illustrates the initial integration of CASE technology into the JTLS software lifecycle. The Software Engineering Institute's (SEI) software process maturity model is used to measure the utility of CASE integration. Current CASE integration focuses on several areas within the JTLS software process. The software development areas include some of the lower components of software production, testing and configuration management. Areas for future integration include the upper phases of software production. These areas include: requirements analysis, software design, software development scheduling and quality assurance. The main purpose of this paper is to provide simulation managers with a reference point for CASE integration into their projects.
Application-aware adaptation for mobile computing
Authors: M. Satyanarayanan, Brian Noble, Puneet Kumar, Morgan Price
Venue: ACM SIGOPS Operating Systems Review (1995)

This paper identifies application-aware adaptation as an essential capability of mobile clients, and provides an overview of Odyssey, an architecture that supports this capability. Functionality that has hitherto been implemented monolithically must now be split between the operating system and individual applications. The role of the operating system is to sense external events, and to monitor and allocate scarce resources. In contrast, the role of individual applications is to adapt to changing conditions by using the information and resources provided by the operating system.
Programming pedagogy&mdash;a psychological overview
Authors: Leon E. Winslow
Venue: ACM SIGCSE Bulletin (1996)

Can we turn novices into experts in a four year undergraduate program? If so, how? If not, what is the best we can do? While every teacher has his/her own opinion on these questions, psychological studies over the last twenty years have started to furnish scientific answers. Unfortunately, little of these results have been incorporated into curricula or textbooks. This report is a brief overview of some of the more important results concerning computer programming and how they can affect course design.
Visualization of the microcirculation by laser Doppler perfusion imaging
Authors: Karin Wȧrdell, Chris Anderson, Thomas Andersson
Venue: ACM SIGBIO Newsletter (1995)

Over the last decade a number of emerging technologies have become available for the study of microvascular blood flow. Some of these methods traumatize the tissue and seriously disturb the microcirculation; others have practical limitations in clinical use. Methods for clinical studies of the blood flow in small vessels should therefore preferably be non-invasive, versatile and easy to use. Most of the available methods that fulfill these conditions are based on optical measurement technology e.g. videomicroscopy [Fagrell et al., 1977], photopletysmography [Challoner 1979] and laser Doppler flowmetry [Nilsson et al., 1980 a,b]. Among these methods, the fiber based laser Doppler technique is the most common. This technique makes possible continuous recording of tissue blood flow at one or several sites. Because of the large spatial variation in tissue blood flow [Braverman et al., 1990] it would, however, be preferable to record the perfusion from a larger area allowing visualization of the spatial variations in tissue blood flow. This paper describes a non-invasive and nocontact system for mapping tissue perfusion, laser Doppler perfusion imaging (LDI). In addition, some potential clinical applications are illustrated.
Let-floating: moving bindings to give faster programs
Authors: Simon Peyton Jones, Will Partain, André Santos
Venue: Proceedings of the first ACM SIGPLAN international conference on Functional programming (1996)

Virtually every compiler performs transformations on the program it is compiling in an attempt to improve efficiency. Despite their importance, however, there have been few systematic attempts to categorise such transformations and measure their impact.In this paper we describe a particular group of transformations --- the "let-floating" transformations --- and give detailed measurements of their effect in an optimizing compiler for the non-strict functional language Haskell. Let-floating has not received much explicit attention in the past, but our measurements show that it is an important group of transformations (at least for lazy languages), offering a reduction of more than 30% in heap allocation and 15% in execution time.
Boundary Layer Resolving Pseudospectral Methods for Singular Perturbation Problems
Authors: Tao Tang, Manfred R. Trummer
Venue: SIAM Journal on Scientific Computing (1996)

Pseudospectral methods are investigated for singularly perturbed boundary value problems for ordinary differential equations (ODEs) which possess boundary layers. It is well known that if the boundary layer is very small then a very large number of spectral collocation points is required to obtain accurate solutions. We introduce here a new effective procedure based on coordinate stretching and the Chebyshev pseudospectral method to resolve the boundary layers. Stable and accurate results are obtained for very thin boundary layers with a fairly small number of spectral collocation points.
Copy detection mechanisms for digital documents
Authors: Sergey Brin, James Davis, Héctor García-Molina
Venue: Proceedings of the 1995 ACM SIGMOD international conference on Management of data (1995)

In a digital library system, documents are available in digital form and therefore are more easily copied and their copyrights are more easily violated. This is a very serious problem, as it discourages owners of valuable information from sharing it with authorized users. There are two main philosophies for addressing this problem: prevention and detection. The former actually makes unauthorized use of documents difficult or impossible while the latter makes it easier to discover such activity.In this paper we propose a system for registering documents and then detecting copies, either complete copies or partial copies. We describe algorithms for such detection, and metrics required for evaluating detection mechanisms (covering accuracy, efficiency, and security). We also describe a working prototype, called COPS, describe implementation issues, and present experimental results that suggest the proper settings for copy detection parameters.
Optimization of functional programs by grammar thinning
Authors: Adam Webber
Venue: ACM Transactions on Programming Languages and Systems (TOPLAS) (1995)

We describe a new technique for optimizing first-order functional programs. Programs are represented as graph grammars, and optimization proceeds by counterexample: when a graph generated by the grammar is found to contain an unnecessary computation, the optimizer attempts to reformulates the grammar so that it never again generates any graph that contains that counterexample. This kind of program reformulation corresponds to an interesting problem on context-free grammars. Our reformulation technique is derived from an (approximate) solution to this CFG problem. An optimizer called Thinner is the proof of concept for this technique. Thinner is a fully automatic, source-to-source optimizer for a Lisp-like language of purely functional, first-order programs. Thinner rediscovers a wide variety of common compiler optimizations. It also finds other more exotic transformations, including the well-known Fibonacci reformulation and the Knuth-Morris-Pratt optimization.
Rectilinear Path Problems Among Rectilinear ObstaclesRevisited
Authors: Chung-Do Yang, D. T. Lee, C. K. Wong
Venue: SIAM Journal on Computing (1995)

Efficient algorithms are presented for finding rectilinear collision-free paths between two given points among a set of rectilinear obstacles. The results improve the time complexity of previous results for finding the shortest rectilinear path, the minimum-bend shortest rectilinear path, the shortest minimum-bend rectilinear path and the minimum-cost rectilinear path. For finding the shortest rectilinear path, a graph-theoretic approach is used and an algorithm is obtained with $O(m\log t+ t\log^{3/2} t)$ running time, where $t$ is the number of extreme edges of given obstacles and $m$ is the number of obstacle edges. Based on this result an $O(N\log N+(m+N)\log t + (t+N)\log^2 (t+N))$ running time algorithm for computing the $L_1$ minimum spanning tree of given $N$ terminals among rectilinear obstacles is obtained. For finding the minimum-bend shortest path, the shortest minimum-bend rectilinear path, and the minimum-cost rectilinear path, we devise a new dynamic-searching approach and derive algorithms that run in $O(m\log^2m)$ time using $O(m\log m)$ space or run in $O(m\log^{3/2}m)$ time and space.
Object oriented experiences
Authors: John Hunt
Venue: ACM SIGPLAN OOPS Messenger (1995)

I have been involved in developing diagnostic and in particular Failure Mode effects Analysis (FMEA) software2 using a variety of Object Oriented Languages (CLOS Smalltalk and POP-11 with a set of Flavours like langauge extensions termed POP++). These applications have concentrated on the electrical domain which has traditionally been dominated by Fortran and C.
Scheduling and mapping: software pipelining in the presence of structural hazards
Authors: Erik R. Altman, R. Govindarajan, Guang R. Gao
Venue: Proceedings of the ACM SIGPLAN 1995 conference on Programming language design and implementation (1995)

Recently, software pipelining methods based on an ILP (Integer Linear Programming) framework have been successfully applied to derive rate-optimal schedules for architectures involving clean pipelines - pipelines without structural hazards. The problem for architectures beyond such clean pipelines remains open. One challenge is how, under a unified ILP framework, to simultaneously represent resource constraints for unclean pipelines, and the assignment or mapping of operations from a loop to those pipelines. In this paper we provide a framework which does exactly this, and in addition constructs rate-optimal software pipelined schedules. The proposed formulation and a solution method have been implemented and tested on a set of 1006 loops taken from various scientific and integer benchmark suites. The formulation found a rate-optimal schedule for 75% of the loops, and required a median time of only 2 seconds per loop on a Sparc 10/30.
An open abstract-object storage system
Authors: Stephen Blott, Lukas Relly, Hans-Jörg Schek
Venue: ACM SIGMOD Record (1996)

Database systems must become more open to retain their relevance as a technology of choice and necessity. Openness implies not only databases exporting their data, but also exporting their services. This is as true in classical application areas as in non-classical (GIS, multimedia, design, etc).This paper addresses the problem of exporting storage-management services of indexing, replication and basic query processing. We describe an abstract-object storage model which provides the basic mechanism, 'likeness', through which these services are applied uniformly to internally-stored, internally-defined data, and to externally-stored, externally-defined data. Managing external data requires the coupling of external operations to the database system. We discuss the interfaces and protocols required of these to achieve correct resource management and admit efficient realisation. Throughout, we demonstrate our solutions in the area of semi-structured file management; in our case, geospatial metadata files.