ppxscal/embedding_network huggingface dataset:
A-BDF: A Generalization of the Backward Differentiation Formulae
Authors: Christoph Fredebeul
Venue: SIAM Journal on Numerical Analysis (1998)

A one parameter family of generalized BDF, the so-called A-BDF, is proposed and analyzed. Formulae of this new family are A0-stable up to order 7, especially A-stable in orders 1 and 2 and $A(\alpha)$-stable in orders 3 to 7, respectively. The nonexistence result of A0-stable formulae of order larger than 7, given by [C. W. Cryer, BIT, 12 (1972), pp. 17--25], [D. M. Creedon and J. J. H. Miller, BIT, 15 (1975), pp. 244--249], is extended to the A-BDF. After implementing these formulae in LSODE, a considerably larger set of stiff problems with oscillatory modes can be solved efficiently and accurately.
Three approximation techniques for ASTRAL symbolic model checking of infinite state real-time systems
Authors: Zhe Dang, Richard A. Kemmerer
Venue: Proceedings of the 22nd international conference on Software engineering (2000)

ASTRAL is a high-level formal specification language for real-time systems. It has structuring mechanisms that allow one to build modularized specifications of complex real-time systems with layering. Based upon the ASTRAL symbolic model checler reported in [13], three approximation techniques to speed-up the model checking process for use in debugging a specification are presented. The techniques are random walk, partial image and dynamic environment generation. Ten mutation tests on a railroad crossing benchmark are used to compare the performance of the techniques applied separately and in combination. The test results are presented and analyzed.
Partial Unitals and Related Structures in DesarguesianPlanes
Authors: Simeon Ball
Venue: Designs, Codes and Cryptography (1998)

It is shown that a partial unital with more than q \sqrt{q} + 1 - \sqrt{q} points in the Desarguesian plane of order q can be extended to a unital.
Boolean Normal Forms, Shellability, and Reliability Computations
Authors: Endre Boros, Yves Crama, Oya Ekin, Peter L. Hammer, Toshihide Ibaraki, Alexander Kogan
Venue: SIAM Journal on Discrete Mathematics (2000)

Orthogonal forms of positive Boolean functions play an important role in reliability theory, since the probability that they take value 1 can be easily computed. However, few classes of disjunctive normal forms are known for which orthogonalization can be efficiently performed. An interesting class with this property is the class of shellable disjunctive normal forms (DNFs). In this paper, we present some new results about shellability. We establish that every positive Boolean function can be represented by a shellable DNF, we propose a polynomial procedure to compute the dual of a shellable DNF, and we prove that testing the so-called lexico-exchange (LE) property (a strengthening of shellability) is NP-complete.
Provably good algorithm for low power consumption with dual supply voltages
Authors: Chunhong Chen, Majid Sarrafzadeh
Venue: Proceedings of the 1999 IEEE/ACM international conference on Computer-aided design (1999)

Dual-voltage approach emerges as an effective and practical technique for power reduction. In this paper we explore the power optimization with dual supply voltages under the given timing constraints. By analyzing the relations among the timing slack, delay and power consumption in a given circuit, we relate the voltage-scaling power optimization to Maximal-Weighted-Independent-Set (MWIS) problem which is polynomial-time solvable on transitive graph. Then we develop a provably good lower-bound algorithm based on MWIS to generate the lower bound of power consumption. Also, we propose a fast approach to predict the optimum supply voltages. The maximum power reduction is obtained by using the modified lower-bound algorithm with optimum voltages. Experimental results show that the resulting lower bound is tight for most circuits and that the estimated optimum supply voltage is exactly, or very close to, the best choice of actual voltages.
&ldquo;The Cobol dinosaur&rdquo;: does it face extinction?
Authors: Malini Krishnamurthi
Venue: ACM SIGUCCS Newsletter (1998)

COBOL (common business oriented language) is a traditional third generation language that was introduced in 1959 and has been in use from then until now. Its longevity seems awesome to many.
NiagaraCQ: a scalable continuous query system for Internet databases
Authors: Jianjun Chen, David J. DeWitt, Feng Tian, Yuan Wang
Venue: ACM SIGMOD Record (2000)

Continuous queries are persistent queries that allow users to receive new results when they become available. While continuous query systems can transform a passive web into an active environment, they need to be able to support millions of queries due to the scale of the Internet. No existing systems have achieved this level of scalability. NiagaraCQ addresses this problem by grouping continuous queries based on the observation that many web queries share similar structures. Grouped queries can share the common computation, tend to fit in memory and can reduce the I/O cost significantly. Furthermore, grouping on selection predicates can eliminate a large number of unnecessary query invocations. Our grouping technique is distinguished from previous group optimization approaches in the following ways. First, we use an incremental group optimization strategy with dynamic re-grouping. New queries are added to existing query groups, without having to regroup already installed queries. Second, we use a query-split scheme that requires minimal changes to a general-purpose query engine. Third, NiagaraCQ groups both change-based and timer-based queries in a uniform way. To insure that NiagaraCQ is scalable, we have also employed other techniques including incremental evaluation of continuous queries, use of both pull and push models for detecting heterogeneous data source changes, and memory caching. This paper presents the design of NiagaraCQ system and gives some experimental results on the system's performance and scalability.
Sample-Path Optimality and Variance-Minimization of Average Cost Markov Control Processes
Authors: Onésimo Hernández-Lerma, Oscar Vega-Amaya, Guadalupe Carrasco
Venue: SIAM Journal on Control and Optimization (1999)

This paper studies several average-cost criteria for Markov control processes on Borel spaces with possibly unbounded costs. Under suitable hypotheses we show (i) the existence of a sample-path average cost (SPAC-) optimal stationary policy; (ii) a stationary policy is SPAC-optimal if and only if it is expected average cost (EAC-) optimal; and (iii) within the class of stationary SPAC-optimal (equivalently, EAC-optimal) policies there exists one with a minimal limiting average variance.
Low power mixed analog-digital signal processing
Authors: Mattias Duppils, Christer Svensson
Venue: Proceedings of the 2000 international symposium on Low power electronics and design (2000)

The power consumption of mixed-signal systems featured by an analog front-end, a digital back-end, and with signal processing tasks that can be computed with multiplications and accumulaðtions, is analyzed. An implementation is proposed, composed of switched-capacitor mixed analog/digital multiply accumulate units in the analog front-end, followed by an A/D converter. This impleðmentation is shown to be superior in respect of power consumption compared to an equivalent implementation with a high-speed A/D converter in the front-end, to execute signal processing tasks that include decimation. The power savings are only due to relaxed requirement on A/D conversion rate, as a direct consequence of the decimation. In a case study of a narrowband FIR filter, realized with four multiply accumulate units, and with a decimation factor of 100; power saving is 54 times. Implementation details are given, the power consumption, and the thermal noise are analyzed.
Has our curriculum become math-phobic? (an American perspective)
Authors: Charles Kelemen, Allen Tucker, Peter Henderson, Owen Astrachan, Kim Bruce
Venue: ACM SIGCSE Bulletin (2000)

We are concerned about a view in undergraduate computer science education, especially in the early courses, that it's okay to be math-phobic and still prepare oneself to become a computer scientist. Our view is the contrary: that any serious study of computer science requires students to achieve mathematical maturity (especially in discrete mathematics) early in their undergraduate studies, thus becoming well-prepared to integrate mathematical ideas, notations, and methodologies throughout their study of computer science. A major curricular implication of this theme is that the prerequisite expectations and conceptual level of the first discrete mathematics course should be the same as it is for the first calculus course --- secondary school pre-calculus and trigonometry. Ultimately, calculus, linear algebra, and statistics are also essential for computer science majors, but none should occur earlier than discrete mathematics. This paper explains our concerns and outlines our response as a series of examples and recommendations for future action.
Unroll-based register coalescing
Authors: Suhyun Kim, Soo-Mook Moon, Jinpyo Park, Kemal Ebcioğlu
Venue: Proceedings of the 14th international conference on Supercomputing (2000)

Aggressive instruction scheduling leaves behind many renaming copy instructions that cannot be coalesced due to interferences. These copies take resources, and more seriously, they may cause a stall if they are generated for renaming of multi-latency instructions. This paper proposes a code transformation technique based on loop unrolling which makes those copies coalescible. Two unique features of the technique are its method of determining the precise unroll amount based on an idea of extended live range, and its insertion of special bookkeeping copies at loop exits. In fact, the technique provides a more general and simpler solution for the cross-iteration register overwrite problem in software pipelining which works for loops with control flows as well as for straight-line loops. In addition, it is applicable to other optimizations including path length reduction and redundant subscripted reference elimination.Our empirical study performed on a 16-ALU VLIW testbed with a two-cycle load latency shows that 86% of the otherwise uncoalescible copies in innermost loops become coalescible when unrolled 2.2 times on average. In addition, it is demonstrated that the unroll amount obtained is precise and the most efficient. The unrolled version of the VLIW code includes fewer no-op VLIWs caused by stalls, improving the performance by a geometric mean of 18%.
Low-Power CMOS Analog Signal Processing Using Spatial Mapping
Authors: Sigbjørn Næss, Tor Sverre Lande
Venue: Analog Integrated Circuits and Signal Processing (1999)

This paper presents a low-power analog circuit for signal processing on pulse coded signals using spatial mapping. By successively delaying a periodic pulse train, and correlating delayed copies of the input signal with the input signal itself, the frequency component(s) are mapped spatially to output signals. The single delay line structure is then extended to a parallel structure with redundancy. In this way, we improve the signal-to-noise ratio. The design has been simulated and fabricated, and both simulation measurement results are presented, indicating the feasibility of the proposed methods.
Distributed, parallel simulation of multiple, deliberative agents
Authors: A. M. Uhrmacher, K. Gugler
Venue: Proceedings of the fourteenth workshop on Parallel and distributed simulation (2000)

Multi-agent systems comprise multiple, deliberative agents embedded in and recreating patterns of interactions. Each agent's execution consumes considerable storage and calculation capacities. For testing multi-agent systems, distributed parallel simulation techniques are required that take the dynamic pattern of composition and interaction of multi-agent systems into account. Analyzing the behavior of agents in virtual, dynamic environments necessitates relating the simulation time to the actual execution time of agents. Since the execution time of deliberative components can hardly be foretold, conservative techniques based on lookahead are not applicable. On the other hand, optimistic techniques become very expensive if mobile agents and the creation and deletion of model components are affected by a rollback. The developed simulation layer of JAMES (a Java Based Agent Modeling Environment for Simulation) implements a moderately optimistic strategy which splits simulation and external deliberation into different threads and allows simulation and deliberation to proceed concurrently by utilizing simulation events as synchronization points.
Hierarchies and relative operators in the OLAP environment
Authors: Elaheh Pourabbas, Maurizio Rafanelli
Venue: ACM SIGMOD Record (2000)

In the last few years, numerous proposals for modelling and querying Multidimensional Databases (MDDB) are proposed. A rigorous classification of the different types of hierarchies is still an open problem. In this paper we propose and discuss some different types of hierarchies within a single dimension of a cube. These hierarchies divide in different levels of aggregation a single dimension. Depending on them, we discuss the characterization of some OLAP operators that refer to hierarchies in order to maintain the data cube consistency. Moreover, we propose a set of operators for changing the hierarchy structure. The issues discussed provide modelling flexibility during the scheme design phase and correct data analysis.
Stable Difference Schemes for Parabolic Systems---A Numerical Radius Approach II
Authors: Moshe Goldberg
Venue: SIAM Journal on Numerical Analysis (1998)

In this paper, a numerical radius approach is taken in order to further discuss stability conditions for a well-known family of finite difference schemes for the initial value problem associated with the Petrowski well-posed, multispace-dimensional parabolic system $$ \dst \frac{\partial \mathbf{u}(\mathbf{x}, t)}{\partial t} = \dst \sum_{1 \leq p \leq q \leq s} A_{pq} \dst \frac{\partial^2\mathbf{u}(\mathbf{x}, t)}{\partial x_p \partial x_q} + \sum_{1 \leq p \leq s} B_p \frac{\partial\mathbf{u}(\mathbf{x}, t)}{\partial x_p} + C\mathbf{u}(\mathbf{x}, t), $$ \noindent where $A_{pq}$, $B_p$, and $C$ are constant matrices, $A_{pq}$ being Hermitian.
What makes Internet users visit cyber stores again? key design factors for customer loyalty
Authors: Jungwon Lee, Jinwoo Kim, Jae Yun Moon
Venue: Proceedings of the SIGCHI conference on Human factors in computing systems (2000)

Retaining customer loyalty is crucial in electronic commerce because the value of an Internet store is largely determined by the number of its loyal customers. This paper proposes a multi-phased model of customer loyalty for Internet shopping, which fully takes the characteristics of the Internet and cyber shopping into consideration. In order to validate the model, we conducted a web-based survey of the customers of various Internet stores, and the data was processed using structural equation analysis. The results indicate that several factors can effectively increase customer loyalty towards an Internet store and that the relative importance of the identified factors varies according to the level of involvement with the product purchased through the store. We suggest several managerial implications in developing Internet stores for higher customer loyalty based on these results.
Generating statechart designs from scenarios
Authors: Jon Whittle, Johann Schumann
Venue: Proceedings of the 22nd international conference on Software engineering (2000)

This paper presents an algorithm for automatically generating UML statecharts from a collection of UML sequence diagrams. Computer support for this transition between requirements and design is important for a successful application of UML's highly iterative, distributed software development process. There are three main issues which must be addressed when generating statecharts from sequence diagrams. Firstly, conflicts arising from the merging of independently developed sequence diagrams must be detected and resolved. Secondly, different sequence diagrams often contain identical or similar behaviors. For a true interleaving of the sequence diagrams, these behaviors must be recognized and merged. Finally, generated statecharts usually are only an approximation of the system and thus must be hand-modified and refined by designers. As such, the generated artifact should be highly structured and readable. In terms of statecharts, this corresponds to the introduction of hierarchy. Our algorithm successfully tackles all three of these aspects and will be illustrated in this paper with a well-known ATM example.
An Analysis of Bid-Price Controls for Network Revenue Management
Authors: Kalyan Talluri, Garrett Van Ryzin
Venue: Management Science (1998)

Bid-prices are becoming an increasingly popular method for controlling the sale of inventoryin revenue management applications. In this form of control, threshold-or "bid"-prices are set for the resources or units of inventory (seats on flight legs, hotel rooms on specific dates, etc.) and a product (a seat in a fare class on an itinerary or room for a sequence of dates) is sold only if the offered fare exceeds the sum of the threshold prices of all the resources needed to supply the product. This approach is appealing on intuitive and practical grounds, but the theory underlying it is not well developed. Moreover, the extent to which bid-price controls represent optimal or near optimal policies is not well understood. Using a general model of the demand process, we show that bid-price control is not optimal in general and analyze why bid-price schemes can fail to produce correct accept/deny decisions. However, we prove that when leg capacities and sales volumes are large, bid-price controls are asymptotically optimal, provided the right bid prices are used. We also provide analytical upper bounds on the optimal revenue. In addition, we analyze properties of the asymptotically optimal bid prices. For example, we show they are constant over time, even when demand is nonstationary, and that they may not be unique.
People, business and IT skills: the perspective of women in the IT industry
Authors: L. A. von Hellens, R. Pringle, S. H. Nielsen, A. Greenhill
Venue: Proceedings of the 2000 ACM SIGCPR conference on Computer personnel research (2000)

This paper discusses professional women's perceptions of the skills required for working in the information technology (IT) industry with respect to the skills women bring to IT work and how the skills contribute to their career progression. The paper references interviews with ten women IT professionals who were asked to describe their entry into the IT industry, their perceptions of IT careers and the skills requirements for success. It was found that an ability to switch between different types of skills (people skills and technical skills) and to adapt to different IT environments contributed to the career progression of women in the IT industry. In the newer areas of IT such as electronic commerce, the ability to switch between one skill set to another is important for the success of such applications. It is suggested that the misrepresentation of the specialization available in the IT industry is an important factor contributing to the gender gap at higher managerial levels and it can only be closed if the range of skills, aptitudes and career paths are made clear to the women.
Integrity constraints for XML
Authors: Wenfei Fan, Jérôme Siméon
Venue: Proceedings of the nineteenth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems (2000)

Integrity constraints are useful for semantic specification, query optimization and data integration. The ID/IDREF mechanism provided by XML DTDs relics on a simple form of constraint to describe references. Yet, this mechanism is not sufficient to express semantic constraints, such as keys or inverse relationships, or stronger, object-style references. In this paper, we investigate integrity constraints for XML, both for semantic purposes and to improve its current reference mechanism. We extend DTDs with several families of constraints, including key, foreign key, inverse constraints and constraints specifying the semantics of object identities. These constraints are useful both for native XML documents and to preserve the semantics of data originating in relational or object databases. Complexity and axiomatization results are established for the (finite) implication problems associated with these constraints. These results also extend relational dependency theory on the interaction between (primary) keys and foreign keys. In addition, we investigate implication of more general constraints, such as functional, inclusion and inverse constraints defined in terms of navigation paths.
Linear Bicharacteristic Schemes Without Dissipation
Authors: Philip Roe
Venue: SIAM Journal on Scientific Computing (1998)

This paper is concerned with developing methods for the propagation of linear waves in several space dimensions. The methods are time reversible and hence are free from numerical dissipation. They are based on bicharacteristic forms of the governing equations and are made possible by adopting forms of staggered storage that depend on the precise equations under consideration. Analysis is presented for the equations of acoustics, electromagnetics, and elastodynamics.
Survivability performance analysis of rerouting strategies in an ATM/VP DCS survivable mesh network
Authors: Kyamakya Kyandoghere
Venue: ACM SIGCOMM Computer Communication Review (1998)

Several self-healing protocols utilizing virtual paths have been proposed in the relevant literature. Those which work in a mesh topology function according to three main rerouting strategies (though specific flooding administrations differ): local rerouting, source-destination rerouting, and local-destination rerouting. Most performance studies of self-healing protocols have considered restoration time as sole performance metric. This would have to be within the 2s threshold in order to guarantee service continuity. This one-sided metric needs to be completed. In this paper, I propose an extended performance(or goodness) metric framework in order to catch more performance aspects. In addition, this analysis uses survivability functions to measure the performance of rerouting strategies.
APL-generated teaching and testing items to enhance a student's ability to discover functional relationships
Authors: Alvin J. Surkan
Venue: Proceedings of the conference on APL '99 : On track to the 21st century: On track to the 21st century (1999)

Ideas and designs for programs to generate teaching examples are introduced. Some of these ideas are tested and demonstrated by a prototype APL program. Descriptions of the internal structure and requirements of the example generators are presented. The examples produced by the program are designed to motivate students to discover rules or relationships capable of mapping the in-domain inputs to correct outputs. Experimental examples used for demonstrating typical concepts and mathematical processes include the functions rho;, , x, +, divide;, | and with their intrinsic APL definitions. Initially, the types of arguments for these examples will be kept simple at first to promote learning such mathematical functions by permitting only single scalar arguments. Later, for discovery learning, the functions may be selected to permit or require arguments that are vector or array objects. An important component in the design of this system is parameter specification. Parameters determine the number of examples and their perspicuity. A student using the system may request additional examples that are easy to comprehend before the function is discovered from the program generated examples provided. The example-generating program also facilitates checking that establishes that a student's response is operationally equivalent to a correct one.