ppxscal/embedding_network huggingface dataset:
Simulation-based comparisons of Tahoe, Reno and SACK TCP
Authors: Kevin Fall, Sally Floyd
Venue: ACM SIGCOMM Computer Communication Review (1996)

This paper uses simulations to explore the benefits of adding selective acknowledgments (SACK) and selective repeat to TCP. We compare Tahoe and Reno TCP, the two most common reference implementations for TCP, with two modified versions of Reno TCP. The first version is New-Reno TCP, a modified version of TCP without SACK that avoids some of Reno TCP's performance problems when multiple packets are dropped from a window of data. The second version is SACK TCP, a conservative extension of Reno TCP modified to use the SACK option being proposed in the Internet Engineering Task Force (IETF). We describe the congestion control algorithms in our simulated implementation of SACK TCP and show that while selective acknowledgments are not required to solve Reno TCP's performance problems when multiple packets are dropped, the absence of selective acknowledgments does impose limits to TCP's ultimate performance. In particular, we show that without selective acknowledgments, TCP implementations are constrained to either retransmit at most one dropped packet per round-trip time, or to retransmit packets that might have already been successfully delivered.
UniSQL's next-generation object-relational database management system
Authors: Albert D'Andrea, Phil Janus
Venue: ACM SIGMOD Record (1996)

Object-Relational DBMSs have been receiving a great deal of attention from industry analysts and press as the next generation of database management systems. The motivation for a next generation DBMS is driven by the reality of shortened business cycles. This dynamic environment demands fast, cost-effective, time-to-market of new or modified business processes, services, and products. To support this important business need, the next generation DBMS must: 1. leverage the large investments made in existing relational technology, both in data and skill set; 2. Take advantage of the flexibility, productivity, and performance benefits of OO modeling; and 3. Integrate robust DBMS services for production quality systems. The objective of this article is to provide a brief overview of UniSQL's commercial object-relational database management system.
Estimating the benefit of the parallelisation of discrete event simulation
Authors: Simon J. E. Taylor, Farshad Fatin, Thierry Delaitre
Venue: Proceedings of the 27th conference on Winter simulation (1995)

This paper presents a technique which attempts to aid the simulationist in the decision as to whether or not simulation should be implemented on a multiprocessing computer. The proposed technique has been used to estimate the performance of parallel discrete event simulations. This employs critical path analysis to determine the lower bound of the execution time of a parallelised simulation and has been used by other authors to study the effect that process scheduling and causality maintenance protocols have on performance. The contribution of this paper is the extension of this technique to a class of common simulation models which demand resource sharing. This forces a parallel implementation to use some kind of information exchange protocol. A case study is presented which illustrates the potential usefulness of this technique. This employs a performance analysis tool developed for this purpose which has been implemented using the simulation package SES/Workbench.
A Total Ordering Multicast Protocol Using Propagation Trees
Authors: Xiaohua Jia
Venue: IEEE Transactions on Parallel and Distributed Systems (1995)

The paper discusses a multicast mechanism using propagation trees. It guarantees the total ordering (including causal ordering) of messages in multiple groups. The mechanism introduces a concept of meta-groups (a subset of a multicast group) and organizes meta-groups into propagation trees. Compared with the existing propagation tree mechanisms, this mechanism has the following advantages: 1) Greater parallelism. Messages can be sent to destinations by using broadcast networks. 2) Less message cost and less latency time. It takes less network communication to multicast a message and less time to have the message delivered to all the destinations. 3) More flexibility to dynamic membership changes and higher reliability for message propagation. It does not need to restructure propagation trees when there is a change in membership, and a site failure does not stop the message propagation to its descendants in the tree.Index Terms¿Atomicity of group communication, distributed systems, message ordering, multicast protocols, network communication, process synchronization.
Defining InterNIC support services
Authors: Tom Newell
Venue: ACM SIGUCCS Newsletter (1995)

As a result of the changing face of the Internet and consequently, the changing demands and requirements of its users, the InterNIC is examining its role in the support it provides to Network Information Center (NIC) staff and other members of the Research and Education (R amp;E) community who supports Internet users. InterNIC Support Services is a new program aimed at investigating this potential role of the InterNIC team. The NIC Liaison, Tom Newell, is charged with developing this new service and formally presented its goals at the 1995 ACM, SIGUCCS meeting in St. Louis, both entertaining questions and inviting community participation in the effort.
Decomposition of magic rewriting
Authors: Ke Wang, Weining Zhang, Siu-Cheung Chau
Venue: Journal of the ACM (JACM) (1995)

The magic rewriting focuses on relevant data but suffers from additional rules, predicates, and tuples that are generated in search for the relevant data. Reducing the arity of predicates can cut down the number of such rules, predicates, and tuples by an exponential factor. In this paper, we consider a subclass of linear single-IDB programs and show that the magic rewriting can be decomposed in such a way that it is applied to only programs having smaller arities and fewer recursive rules, without losing the binding capacity. The decomposed rewriting is shown to be much more efficient than the standard one and amenable to distributed and parallel environments. The considered subclass significantly generalizes recursions previously proposed for efficient implementation. The decomposed rewriting and the standard generalized magic rewriting are extended to multi-binding queries in such a way that data relevant to one binding is not necessarily considered as relevant to other bindings. The work in this paper shows the use of tuple ID as an important technique in optimizing logic programs.
An experience teaching formal methods in discrete mathematics
Authors: J. Stanley Warford
Venue: ACM SIGCSE Bulletin (1995)

In spite of recent calls to incorporate formal methods into the computer science curriculum, the effort is still controversial and proceeding slowly. This paper presents our experience in restructuring the undergraduate Discrete Mathematics course to include formal methods. It concludes with some philosophical ruminations about the place of formal methods in the computer science curriculum in general.
Drawing graphs nicely using simulated annealing
Authors: Ron Davidson, David Harel
Venue: ACM Transactions on Graphics (TOG) (1996)

The paradigm of simulated annealing is applied to the problem of drawing graphs &ldquo;nicely.&rdquo; Our algorithm deals with general undirected graphs with straight-line edges, and employs several simple criteria for the aesthetic quality of the result. The algorithm is flexible, in that the relative weights of the criteria can be changed. For graphs of modest size it produces good results, competitive with those produced by other methods, notably, the &ldquo;spring method&rdquo; and its variants.
On designing ULM-based FPGA logic modules
Authors: Shashidhar Thakur, D. F. Wong
Venue: Proceedings of the 1995 ACM third international symposium on Field-programmable gate arrays (1995)

In this paper, we give a method to design FPGA logic modules, based on an extension of classical work on designing Universal Logic Modules (ULM). Specifically, we give a technique to design a class of logic modules that specialize to a large number of functions under complementations and permutations of inputs, bridging of inputs and assignment of 0/1 to inputs. Thus, a lot of functions can be implemented using a single logic module. The significance of our work lies in our ability to generate a large set of such logic modules. A choice can be made from this set based on design criteria. We demonstrate the technique by generating a set of 471 8-input functions that have a much higher coverage than the 8-input cells employed by Actel's FP-GAs. Our functions can specialize to up to 23 times the number of functions that Actel functions can. We also show that by carefully optimizing these functions one can obtain multi-level implementations of them that have delays within 10% of the delays of Actel modules. We demonstrates the effectiveness of these modules in mapping benchmark circuits. We observed a 16% reduction in area and a 21% reduction in delay using our logic modules instead of Actel's on these circuits.
Simultaneous depth and area minimization in LUT-based FPGA mapping
Authors: Jason Cong, Yean-Yow Hwang
Venue: Proceedings of the 1995 ACM third international symposium on Field-programmable gate arrays (1995)

In this paper, we present an improvement of the FlowMap algorithm, named CutMap, which combines depth and area minimization during the mapping process by computing min-cost min-height K-feasible cuts for critical nodes for depth minimization and computing min-cost K-feasible cuts for non-critical nodes for area minimization. CutMap guarantees depth-optimal mapping solutions in polynomial time as the FlowMap algorithm but uses considerably fewer K-Luts. We have implemented CutMap and tested it on the MCNC logic synthesis benchmarks. For depth-optimal mapping solutions, CutMap uses 15% fewer K-LUTs than FlowMap. We also tested CutMap followed by the depth relaxation routines in FlowMap_r algorithm, which achieves area minimization by depth relaxation. CutMap followed FlowMap_r performs better than FlowMap_r.
Reducing false sharing on shared memory multiprocessors through compile time data transformations
Authors: Tor E. Jeremiassen, Susan J. Eggers
Venue: Proceedings of the fifth ACM SIGPLAN symposium on Principles and practice of parallel programming (1995)

We have developed compiler algorithms that analyze explicitly parallel programs and restructure their shared data to reduce the number of false sharing misses. The algorithms analyze per-process shared data accesses, pinpoint the data structures that are susceptible to false sharing and choose an appropriate transformation to reduce it. The transformations either group data that is accessed by the same processor or separate individual data items that are shared.This paper evaluates that technique. We show through simulation that our analysis successfully identifies the data structures that are responsible for most false sharing misses, and then transforms them without unduly decreasing spatial locality. The reduction in false sharing positively impacts both execution time and program scalability when executed on a KSR2. Both factors combine to increase the maximum achievable speedup for all programs, more than doubling it for several. Despite being able to only approximate actual inter-processor memory accesses, the compiler-directed transformations always outperform programmer efforts to eliminate false sharing.
When is double rounding innocuous?
Authors: Samuel A. Figueroa
Venue: ACM SIGNUM Newsletter (1995)

Double rounding is the phenomenon that occurs when the result of an operation is rounded to fit some intermediate destination, and then again when delivered to its final destination. This can be a common occurrence when using some floating-point arithmetic engines which lack single precision registers: results of operations are typically rounded to fit in a register, whose width may be double precision or wider, before being stored in some memory location possibly in a format narrower than that of the registers. Examples of such floating-point arithmetic engines include Intel's x87 series and IBM's POWER architecture. (Implementations of the latter are found in some IBM workstations.)
Interfacing command and control information systems and simulation environments: technical approach, operational payoff and procedural challenges
Authors: Dirk Coppieters
Venue: Proceedings of the 27th conference on Winter simulation (1995)

The paper describes a modular approach for the interfacing of simulation environments and command and control systems. It focuses on the type of interface that is required during the execution of a military exercise. Experiments have been conducted with prototypes that represent subordinate decision making. They tend to show that the same exercise effectiveness can be achieved while reducing the amount of support personnel considerably. A further reduction in personnel can be achieved by modelling of the formal reporting process. A prototype capability has been built and tested in which a report generation mechanism combines all relevant structural and content data stored in a single repository to produce valid reports. This approach has proven successful in the laboratory and must now be tested in the field. A spin-off result is the availability of data to support the monitoring and the analysis of the exercise. It is also necessary to highlight the security and performance implications of implementing such a tight interfacing between an operational command and control system and an exercise driver.
A simple student environment for lightweight process concurrent programming under SunOs
Authors: Toby S. Berk
Venue: ACM SIGCSE Bulletin (1996)

This paper describes a simplified student environment for lightweight processes (threads) under SunOs or compatible systems. The environment is built on top of the SunOs lwp package. A range of concurrency facilities are provided including critical sections, events and signals, and monitors. A hidden scheduler enhances the effects of the nondeterminacy, even for small student programs. A sample assignment is shown using the package.
The reconstruction engine: a computer implementation of the comparative method
Authors: John B. Lowe, Martine Mazaudon
Venue: Computational Linguistics (1994)

We describe the implementation of a computer program, the Reconstruction Engine (RE), which models the comparative method for establishing genetic affiliation among a group of languages. The program is a research tool designed to aid the linguist in evaluating specific hypotheses, by calculating the consequences of a set of postulated sound changes (proposed by the linguist) on complete lexicons of several languages. It divides the lexicons into a phonologically regular part and a part that deviates from the sound laws. RE is bi-directional: given words in modern languages, it can propose cognate sets (with reconstructions); given reconstructions, it can project the modern forms that would result from regular changes. RE operates either interactively, allowing word-by-word evaluation of hypothesized sound changes and semantic shifts, or in a "batch" mode, processing entire multilingual lexicons en masse.We describe the algorithms implemented in RE, specifically the parsing and combinatorial techniques used to make projections upstream or downstream in the sense of time, the procedures for creating and consolidating cognate sets based on these projections, and the ad hoc techniques developed for handling the semantic component of the comparative method.Other programs and computational approaches to historical linguistics are briefly reviewed.Some results from a study of the Tamang languages of Nepal (a subgroup of the Tibeto-Burman family) are presented, and data from these languages are used throughout for exemplification of the operation of the program.Finally, we discuss features of RE that make it possible to handle the complex and sometimes imprecise representations of lexical items, and speculate on possible directions for future research.
Run-away dynamics of CDMA channels in an adaptive packet radio network
Authors: Julio Escobar
Venue: Wireless Networks (1995)

Radio communication offers the great advantage of mobility for users. At least two important systems exploit this feature: packet radio networks and personal communication systems. Since their radio links are subject to rapid changes in quality, the ability to adapt to these changes has much to offer in improving throughput, delay, and robustness characteristics. This paper addresses three areas. First, it presents the design fundamentals of an adaptive link-gain control algorithm for a multiple access radio channel. Second, it develops a probabilistic model for a related family of algorithms, which includes models for the effects of code-division multiple access interference. Third, it uses two sample algorithms to explore the transient behaviour of the system. The two algorithms are chosen to compare the relative merits of designs that emphasize adapting to channel noise versus adapting to multiple access interference. Transient analysis is sparse in the literature and is an important contribution of this paper.
Push-up scheduling: Optimal polynomial-time resource constrained scheduling for multi-dimensional applications
Authors: Nelson Luiz Passos, Edwin Hsing-Mean Sha
Venue: Proceedings of the 1995 IEEE/ACM international conference on Computer-aided design (1995)

Multi-dimensional computing applications, such as image processing and fluid dynamics, usually contain repetitive groups of operations represented by nested loops. The optimization of such loops, considering processing resource constraints, is required to improve their computational time. This study presents a new technique, called push-up scheduling, able to achieve the shortest possible schedule length in polynomial time. Such technique transforms a multi-dimensional data flow graph representing the problem, while assigning the loop operations to a schedule table in such a way to occupy, legally, any empty spot. The algorithm runs in O(n|E|) time, where n is the number of dimensions of the problem, and |E| is the number of edges in the graph.
Model-Based Shape Matching with Structural Feature Grouping
Authors: Hirobumi Nishida
Venue: IEEE Transactions on Pattern Analysis and Machine Intelligence (1995)

An essential problem in on-line handwriting recognition is the shape variation along with the variety of stroke number and stroke order. In this paper we present a clear and systematic approach to shape matching based on structural feature grouping. To cope with topological deformations caused by stroke connection and breaking, we incorporate some aspects of top-down approaches systematically into the shape matching algorithm. The grouping of local structural features into high-level features is controlled by high-level knowledge as well as the simple geometric conditions. The shape matching algorithm has the following properties from the viewpoint of on-line character recognition: 1) stroke order, direction, and number are free, and 2) stroke connection and breaking are allowed.
The Schur Complement Interlacing Theorem
Authors: Shu-An Hu, Ronald L. Smith
Venue: SIAM Journal on Matrix Analysis and Applications (1995)

The following analogue of the converse of the Cauchy Interlacing Theorem is proved: if $ \lambda_1, \lambda_2, \ldots, \lambda_n, \mu_1, \mu_2, \ldots, \mu_{n-r}$ are $2n-r$ real numbers satisfying ${1 \over {\lambda_1}} \ge {1 \over {\lambda_2}} \ge \cdots \ge {1 \over {\lambda_n}}$, ${1 \over {\mu_1}} \ge {1 \over {\mu_2}} \ge \cdots \ge {1 \over {\mu_{n-r}}}$, and ${1 \over {\lambda_i}} \ge {1 \over {\mu_i}} \ge {1 \over {\lambda_{i+r}}}$, $1 \le i \le n-r$, and if the sets $\{ \lambda_1, \lambda_2, \ldots, \lambda_n \}$ and $\{ \mu_1, \mu_2, \ldots, \mu_{n-r} \}$ have the same number of zeros, then there exists an $n \times n$ hermitian matrix $H$ with an $r \times r$ nonsingular principal submatrix $A$ such that the spectra of $H$ and $H/A$ (the Schur complement of $H$ with respect to $A$) are $\{ \lambda_1, \lambda_2, \ldots, \lambda_n \}$ and $\{ \mu_1, \mu_2, \ldots, \mu_{n-r} \}$, respectively. Here, the reciprocal of zero is defined to be zero. This result is then used to prove an analogue for semidefinite matrices.
On automatic class insertion with overloading
Authors: H. Dicky, C. Dony, M. Huchard, T. Libourel
Venue: ACM SIGPLAN Notices (1996)

Several algorithms [Cas92, MS89, Run92, DDHL94a, DDHL95, GMM95] have been proposed to automatically insert a class into an inheritance hierarchy. But actual hierarchies all include overriden and overloaded properties that these algorithms handle either very partially or not at all. Partially handled means handled provided there is a separate given function f able to compare overloaded properties [DDHL95, GMM95].In this paper, we describe a new version of our algorithm (named Ares) which handles automatic class insertion more efficiently using such a function f. Although impossible to fully define, this function can be computed for a number of well defined cases of overloading and overriding. We give a classification of such cases and describe the computation process for a well-defined set of nontrivial cases.The algorithm preserves these important properties:- preservation of the maximal factorization of properties- preservation of the underlying structure (Galois lattice) of the input hierarchy- conservation of relevant classes of the input hierarchy with their properties.
On the Stochastic Complexity of Learning Realizable and Unrealizable Rules
Authors: Ronny Meir, Neri Merhav
Venue: Machine Learning (1995)

The problem of learning from examples in an average case setting is considered. Focusing on the stochastic complexity, an information theoretic quantity measuring the minimal description length of the data given a class of models, we find rigorous upper and lower bounds for this quantity under various conditions. For realizable problems, where the model class used is sufficiently rich to represent the function giving rise to the examples, we find tight upper and lower bounds for the stochastic complexity. In this case, bounds on the prediction error follow immediately using the methods of Haussler et al. (1994a). For unrealizable learning we find a tight upper bound only in the case of learning within a space of finite VC dimension. Moreover, we show in the latter case that the optimal method for prediction may not be the same as that for data compression, even in the limit of an infinite amount of training data, although the two problems (i.e. prediction and compression) are asymptotically equivalent in the realizable case. This result may bear consequences for many of the widely used model selection methods.
Artificial life meets entertainment: lifelike autonomous agents
Authors: Pattie Maes
Venue: Communications of the ACM (1995)

The relatively new field of artificial life attempts to study and understand biological life by synthesizing artificial life forms. To paraphrase Chris Langton, the founder of the field, the goal of artificial life is to &ldquo;model life as it could be so as to understand life as we know it.&rdquo; Artificial life is a very broad discipline which spans such diverse topics as artificial evolution, artificial ecosystems, artificial morphogenesis, molecular evolution, and many more. Langton offers a nice overview of the different research questions studied by the discipline [6]. Artificial life shares with artificial intelligence (AI) its interest in synthesizing adaptive autonomous agents. Autonomous agents are computational systems that inhabit some complex, dynamic environment, sense and act autonomously in this environment, and by doing so realize a set of goals or tasks for which they are designed.