ppxscal/embedding_network huggingface dataset:
Faster Algorithms for the Generalized Network Flow Problem
Authors: Terri L. Griffith, Mark A. Fuller, Gregory B. Northcraft, Tomasz Radzik
Venue: Mathematics of Operations Research (1998)

We consider the generalized network flow problem. Each arc e in the network has a gain factor &#947;(e). If f(e) units of flow enter arc e, then f(e)&#947;(e) units arrive at the other end of e. The objective is to maximize the net flow into one specific node, the sink. The constraints are the conservation of flow at nodes and the capacities of arcs. We present a combinatorial algorithm which solves this problem in O(m2(m + n log log B)log B) time, where n is the number of nodes, m is the number of arcs, and B is the largest integer used to represent the gain factors, the capacities, and the initial supplies at the nodes. If m is O(n4/3 - &#949;) and B is not extremely large, then our bound is better than the previous best upper bound for this problem. We also improve the best known upper bound for the approximate generalized flow problem by showing that a solution whose value is within a factor of 1 + &#958; from the optimum can be computed in O(m(m + n log log B) log(1/&#958;)) time plus O(mn2 log B) time for preprocessing.
Getting Ada into the mainstream in the 1990's
Authors: Kenneth Fussichen
Venue: Proceedings of the conference on TRI-ADA '90 (1990)

Ada offers a great deal to the MIS community. There are a number of language features that provide attractive tools to the programmer. Ada's support for Object Orientation is far superior to that currently afforded by IBM mainframe languages such as COBOL and PL/1. This translates into more maintainable code, which is the key to MIS Ada acceptance. Unfortunately, Ada introduces problems that do not currently exist in MIS. Decimal arithmetic and string manipulation adequate to support reporting are inherently non-existent. I/O support is inadequate as are DBMS bindings. Conversions are forced on non-ASCII hosts. The compiler has the option of reordering fields within records, rendering non-Ada utilities useless. There is an inexcusable lack of understanding of the targeted market. Virtually all of the known weaknesses of Ada were to be solvable by standard packages to be marketed by compiler vendors as a result of &ldquo;market forces&rdquo;. This is how compiler vendors would differentiate their products. This strategy has failed and no new strategy has replaced or augmented it. The Ada 9X Language Revision Process does offer some hope. Native character sets, decimal arithmetic and what is loosely called &ldquo;secondary standards&rdquo; offer the potential to make MIS Ada acceptable without burdening other disciplines. Ada 9X doesn't have all the answers. Bindings are still a significant problem. This is especially true if there is interest in converting any of the 80 billion lines of COBOL code to Ada. While the Ada-SQL binding will solve the Ada-SQL problem, the binding of the SQL specification to the proprietary DBMS is still left to those mysterious &ldquo;market forces&rdquo;. In my opinion, the Ada community needs MIS support to impact &ldquo;market forces&rdquo;. The Ada community has not demonstrated an understanding of MIS requirements and therefore cannot market to the MIS community. There is no MIS inclination to even acknowledge Ada, therefore any change to the status quo must come from the Ada community. The Ada 9X Language Revision Team has started to address this problem. There may be an MIS Ada awareness in the 1990's, but bringing Ada into the MIS mainstream is more than a decade away.
Optimization of inverted vector searches
Authors: Chris Buckley, Alan F. Lewit
Venue: Proceedings of the 8th annual international ACM SIGIR conference on Research and development in information retrieval (1985)

A simple algorithm is presented for increasing the efficiency of information retrieval searches which are implemented using inverted files. This optimization algorithm employs knowledge about the methods used for weighting document and query terms in order to examine as few inverted lists as possible. An extension to the basic algorithm allows greatly increased performance optimization at a modest cost in retrieval effectiveness. Experimental runs are made examining several different term weighting models and showing the optimization possible with each.
Codes with the Same Weight Distributions as the Goethals Codes and the Delsarte-Goethals Codes
Authors: Tor Helleseth, P. Vijay Kumar, Abhijit Shanbhag
Venue: Designs, Codes and Cryptography (1996)

The Goethals code is a binary nonlinear code of length 2^{m+1} which has 2^{2^{m+1}-3m-2} codewords and minimum Hamming distance 8 for any odd m \geq 3. Recently, Hammons et. al. showed that codes with the same weight distribution can be obtained via the Gray map from a linear code over Z_4 of length 2^m and Lee distance 8. The Gray map of the dual of the corresponding Z_4 code is a Delsarte-Goethals code. We construct codes over Z_4 such that their Gray maps lead to codes with the same weight distribution as the Goethals codes and the Delsarte-Goethals codes.
RASSP Enterprise Technologies for SignalProcessor Life-Cycle Support
Authors: John Welsh, Bipin Chadha, Biju Kalathil, Peter Holmes, Mary Catherine Tuck, William Selvidge, Elisa Finnie, Lynwood Hines
Venue: Journal of VLSI Signal Processing Systems (1997)

Enterprise integration technologies are a key contributor to improving time-to-market, cost, and design quality by a factor, which is the goal of the DARPA Rapid Prototyping of Application-Specific Signal Processors (RASSP) program [1]. The Lockheed Martin Advanced Technology Laboratories (ATL) RASSP team developed a productivity improvement model, shown in Fig. 1, that indicates the relative contributions of various RASSP technologies to the overall improvement. Enterprise technologies address the entire 17% enterprise partition, and more than half of the 30% reuse and model-year architecture partition, thus accounting for at least 35% of the overall RASSP productivity improvement.The ATL RASSP approach to implement enterprise systems is to extend commercial technologies so the results are available to a broad base of potential users. Unlike current automation concepts which start at later stages of the development cycle, the RASSP enterprise system supports the entire signal processor life cycle. Core concepts of the enterprise system include:Tools and tool frameworks integrated into an enterprise environmentProgram execution control through workflowsIntegrated data management functionsDesign reuseConcurrent engineering team supportIntegrated design engineering and manufacturing.The model-year architecture, which enables users to rapidly, efficiently upgrade systems with new technology, is supported in the enterprise system by a robust reuse management system. Manufacturing interface and communication services elements of the enterprise system provide improved concurrent engineering support for distributed product teams. The enterprise system will be provided to commercial and aerospace users as products, including a reusable set of workflows for electronics design, commercial tools supporting the enterprise system environment, and utilities to enable users to customize the RASSP enterprise system for a particular organization or project.The enterprise system development cycle includes four build cycles with increasing capabilities. The ATL team completed the Build 2 implementation in May&lsquo;96. This implementation supports the processes associated with detailed hardware/software design, architecture design, and trade-off analyses. It is being used at Lockheed Martin and multiple government sites for benchmarking and evaluation. Results to date indicate >5:1 productivity improvements in the manufacturing interface, and 5&ndash;10% improvements in design engineering, which is growing with increasing level of utilization.
Negative thinking by incremental problem solving: application to unate covering
Authors: Evguenii I. Goldberg, Luca P. Carloni, Tiziano Villa, Robert K. Brayton, Alberto L. Sangiovanni-Vincentelli
Venue: Proceedings of the 1997 IEEE/ACM international conference on Computer-aided design (1997)

We introduce a new technique to solve exactly a discrete optimization problem, based on the paradigm of "negative" thinking. The motivation is that when searching the space of solutions, often a good solution is reached quickly and then improved only a few times before the optimum is found: hence most of the solution space is explored to certify optimality, but it does not yield any improvement of the cost function. So it is quite natural for an algorithm to be "skeptical" about the chance to improve the current best solution. For illustration we have applied our approach to the unate covering problem. We designed a procedure, raiser, implementing a negative thinking search, which is incorporated into a common branch-and-bound procedure. Raiser is invoked at a node of the search tree which is deep enough to justify negative thinking. Raiser tries to detect a hard core of the matrix corresponding to the node by augmenting an independent set of rows in order to increase incrementally the cost of the minimum solutions covering the matrix. Eventually either raiser prunes the subtree rooted at the node (having found a lower bound equal or greater than the current best solution) or returns a new solution that becomes the current best one. Experiments show that our program, aura, outperforms both espresso and our enhancement of espresso using Coudert's limit lower bound. It is always faster and in the most difficult examples either has a running time better by up to two orders of magnitude, or the other programs fail to finish due to timeout or spaceout. The package scherzo is faster on some examples and loses on others, due to a less powerful pruning strategy of the search space, partially mitigated by a more effective computation of the maximal independent set.
Performance Optimization of Checkpointing Schemes with Task Duplication
Authors: Avi Ziv, Jehoshua Bruck
Venue: IEEE Transactions on Computers (1997)

In checkpointing schemes with task duplication, checkpointing serves two purposes: detecting faults by comparing the processors' states at checkpoints, and reducing fault recovery time by supplying a safe point to rollback to. In this paper, we show that, by tuning the checkpointing schemes to a given architecture, a significant reduction in the execution time can be achieved. The main idea is to use two types of checkpoints: compare-checkpoints (comparing the states of the redundant processes to detect faults) and store-checkpoints (storing the states to reduce recovery time). With two types of checkpoints, we can use both the comparison and storage operations in an efficient way and improve the performance of checkpointing schemes. Results we obtained show that, in some cases, using compare and store checkpoints can reduce the overhead of DMR checkpointing schemes by as much as 30 percent.
Visualizing generalized semi-Markov processes
Authors: Lee W. Schruben, Eric L. Savage
Venue: Proceedings of the 28th conference on Winter simulation (1996)

Generalized Semi-Markov Processes (GSMPs) are usually described by sets of variables, events and clock distributions. This kind of representation often lacks intuitive appeal. In this paper we propose a mapping from GSMPs to Event Graph Models. This mapping allows us to use an event graph to visualize a GSMP model as an intermediate step to implemcniation. By examining the event graph model, we can perform logic checking and verification more easily than if we try to interpret the GSMP description.
Size--Depth Tradeoffs for Threshold Circuits
Authors: Russell Impagliazzo, Ramamohan Paturi, Michael E. Saks
Venue: SIAM Journal on Computing (1997)

The following size--depth tradeoff for threshold circuits is obtained: any threshold circuit of depth $d$ that computes the parity function on $n$ variables must have at least $n^{1 + c\theta^{-d }}$ edges, where $c>0$ and $\theta \leq 3$ are constants independent of $n$ and $d$. Previously known constructions show that up to the choice of $c$ and $\theta$ this bound is best possible. In particular, the lower bound implies an affirmative answer to the conjecture of Paturi and Saks that a bounded-depth threshold circuit that computes parity requires a superlinear number of edges. This is the first superlinear lower bound for an explicit function that holds for any fixed depth and the first that applies to threshold circuits with unrestricted weights. The tradeoff is obtained as a consequence of a general restriction theorem for threshold circuits with a small number of edges: For any threshold circuit with $n$ inputs, depth $d$, and at most $kn$ edges, there exists a partial assignment to the inputs that fixes the output of the circuit to a constant while leaving $\lfloor n/(c_1k)^{c_2\theta^{d}} \rfloor$ variables unfixed, where $c_1,c_2 > 0$ and $ \theta \leq 3$ are constants independent of $n$, $k$, and $d$.A tradeoff between the number of gates and depth is also proved: any threshold circuit of depth $d$ that computes the parity of $n$ variables has at least $(n/2)^{1/2(d-1)}$ gates. This tradeoff, which is essentially the best possible, was proved previously (with a better constant in the exponent) for the case of threshold circuits with polynomially bounded weights in [K. Siu, V. Roychowdury, and T. Kailath, IEEE Trans. Inform. Theory, 40 (1994), pp. 455--466]; the result in the present paper holds for unrestricted weights.
Parallel Incremental Graph Partitioning
Authors: Chao-Wei Ou, Sanjay Ranka
Venue: IEEE Transactions on Parallel and Distributed Systems (1997)

Partitioning graphs into equally large groups of nodes while minimizing the number of edges between different groups is an extremely important problem in parallel computing. For instance, efficiently parallelizing several scientific and engineering applications requires the partitioning of data or tasks among processors such that the computational load on each node is roughly the same, while communication is minimized. Obtaining exact solutions is computationally intractable, since graph partitioning is an NP-complete.For a large class of irregular and adaptive data parallel applications (such as adaptive graphs), the computational structure changes from one phase to another in an incremental fashion. In incremental graph-partitioning problems the partitioning of the graph needs to be updated as the graph changes over time; a small number of nodes or edges may be added or deleted at any given instant.In this paper, we use a linear programming-based method to solve the incremental graph-partitioning problem. All the steps used by our method are inherently parallel and hence our approach can be easily parallelized. By using an initial solution for the graph partitions derived from recursive spectral bisection-based methods, our methods can achieve repartitioning at considerably lower cost than can be obtained by applying recursive spectral bisection. Further, the quality of the partitioning achieved is comparable to that achieved by applying recursive spectral bisection to the incremental graphs from scratch.
Efficient video file allocation schemes for video-on-demand services
Authors: Yuewei Wang, Jonathan C. L. Liu, David H. C. Du, Jenwei Hsieh
Venue: Multimedia Systems (1997)

A video-on-demand (VOD) server needs to store hundreds of movie titles and to support thousands of concurrent accesses. This, technically and economically, imposes a great challenge on the design of the disk storage subsystem of a VOD server. Due to different demands for different movie titles, the numbers of concurrent accesses to each movie can differ a lot. We define access profile as the number of concurrent accesses to each movie title that should be supported by a VOD server. The access profile is derived based on the popularity of each movie title and thus serves as a major design goal for the disk storage subsystem. Since some popular (hot) movie titles may be concurrently accessed by hundreds of users and a current high-end magnetic disk array (disk) can only support tens of concurrent accesses, it is necessary to replicate and/or stripe the hot movie files over multiple disk arrays. The consequence of replication and striping of hot movie titles is the potential increase on the required number of disk arrays. Therefore, how to replicate, stripe, and place the movie files over a minimum number of magnetic disk arrays such that a given access profile can be supported is an important problem. In this paper, we formulate the problem of the video file allocation over disk arrays, demonstrate that it is a NP-hard problem, and present some heuristic algorithms to find the near-optimal solutions. The result of this study can be applied to the design of the storage subsystem of a VOD server to economically minimize the cost or to maximize the utilization of disk arrays.
New call blocking versus handoff blocking in cellular networks
Authors: Moshe Sidi, David Starobinski
Venue: Wireless Networks (1997)

In cellular networks, blocking occurs when a base station has no free channel to allocate to a mobile user. One distinguishes between two kinds of blocking, the first is called new call blocking and refers to blocking of new calls, the second is called handoff blocking and refers to blocking of ongoing calls due to the mobility of the users. In this paper, we first provide explicit analytic expressions for the two kinds of blocking probabilities in two asymptotic regimes, i.e., for very slow mobile users and for very fast mobile users, and show the fundamental differences between these blocking probabilities. Next, an approximation is introduced in order to capture the system behavior for moderate mobility. The approximation is based on the idea of isolating a set of cells and having a simplifying assumption regarding the handoff traffic into this set of cells, while keeping the exact behavior of the traffic between cells in the set. It is shown that a group of 3 cells is enough to capture the difference between the blocking probabilities of handoff call attempts and new call attempts.
Explicit Communication Revisited: Two New Attacks on Authentication Protocols
Authors: Martín Abadi
Venue: IEEE Transactions on Software Engineering (1997)

SSH and AKA are recent, practical protocols for secure connections over an otherwise unprotected network. This paper shows that, despite the use of public-key cryptography, SSH and AKA do not provide authentication as intended. The flaws of SSH and AKA can be viewed as the result of their disregarding a basic principle for the design of sound authentication protocols: the principle that messages should be explicit.
The performance of a prototype coprocessor for Ada tasking
Authors: Joachim Roos
Venue: Proceedings of the conference on TRI-ADA '90 (1990)

A special purpose VLSI coprocessor has been designed to support the real-time functionality of Ada Tasking. The coprocessor has been successfully implemented, and this paper concludes the project by evaluating its performance. The performance is measured by running a large set of benchmarks which test different rendezvous situations. The benchmarks were executed on an experimental VME-bus system connected to the coprocessor, and the results where compared with those obtained when using a number of commercial Ada compilers. Due to the lack of available test suites to cover the multitude of different ways of making a rendezvous a special program that automatically generates benchmarks, the benchmark synthesizer, has been implemented. Its output is a systematic sequence of 208 different programs, where the most important aspects of rendezvous performance are automatically measured. The cost for a rendezvous is shown to depend not only on the language constructs involved, but also on the circumstances in the system, e.g. the number of callers or the number of runable tasks. The results are visualized by diagrams called performance profiles. By comparing the profiles, values of the speed-up are obtained. A detailed analysis of the components of the rendezvous cost in the coprocessor system is made, including software and VME-bus transfers.
Progressive Retry for Software Failure Recovery in Message-Passing Applications
Authors: Yi-Min Wang, Yennun Huang, W. Kent Fuchs, Chandra Kintala
Venue: IEEE Transactions on Computers (1997)

A method of execution retry for bypassing software faults in message-passing applications is described in this paper. Based on the techniques of checkpointing and message logging, we demonstrate the use of message replaying and message reordering as two mechanisms for achieving localized and fast recovery. The approach gradually increases the rollback distance and the number of affected processes when a previous retry fails, and is therefore named progressive retry. Examples from telecommunications software systems and performance measurements from an application-level implementation are described to illustrate the benefits of the scheme.
Advanced uses for Micro Saint simulation software
Authors: Catherine E. Drury, K. Ronald Laughery,  Jr.
Venue: Proceedings of the 28th conference on Winter simulation (1996)

Simulation is fast becoming the software tool for the 1990's. More companies each year are taking advantage of the ease of use of simulation software and see the benefits to using this tool. Unfortunately, there are still many people in Manufacturing, Health Care, Process Reengineering and Human Factors industries who are not using any sort of simulation software. Even in the information age of the 1990's it is still hard for potential simulation users to keep up with the changing market of computers and simulation software. In this paper we will focus on the changes in simulation software over the past ten years, the ease of use of the 1990's simulation software, and the broadening market for simulation software. Then, we wilI illustrate some of these changes by providing a step by step approach to using Micro Saint simulation software Version 2.0.
Analysis of Quorum-Based Protocols for Distributed (k + 1)-Exclusion
Authors: Divyakant Agrawal, Ömer Eğecioǧlu, Amr El Abbadi
Venue: IEEE Transactions on Parallel and Distributed Systems (1997)

A generalization of the majority quorum for the solution of the distributed (k + 1)-exclusion problem is proposed. This scheme produces a family of quorums of varying sizes and availabilities indexed by integral divisors r of k. The cases r = 1 and r = k correspond to known majority based quorum generation algorithms MAJ and DIV, whereas intermediate values of r interpolate between these two extremes. A cost and availability analysis of the proposed methods is also presented. An interesting implication of this analysis is that in a reasonably reliable environment with a large number of sites, even protocols with low communication costs attain high availability.
Selecting the best system in transient simulations with variances known
Authors: Halim Damerdji, Peter W. Glynn, Marvin K. Nakayama, James R. Wilson
Venue: Proceedings of the 28th conference on Winter simulation (1996)

Selection of the best system among k different systems is investigated. This selection is based upon the results of finite-horizon simulations. Since the distribution of the output of a transient simulation is typically unknown, it follows that this problem is that of selection of the best population (best according to some measure) among k different populations, where observations within each population are independent, and identically distributed according to some general (unknown) distribution. In this work in progress, it is assumed that the population variances are known. A natural single-stage sampling procedure is presented. Under Bechbofer's indifference zone approach, this procedure is asymptotically valid.