ppxscal/embedding_network huggingface dataset:
Sorting out signature schemes
Authors: Birgit Pfitzmann
Venue: Proceedings of the 1st ACM conference on Computer and communications security (1993)

Digital signature schemes are a fundamental tool for secure distributed systems. It is important to have a formal notion of what a secure digital signature scheme is, so that there is a clear interface between designers and users of such schemes. A definition that seemed final was given by Goldwasser, Micali, and Rivest in 1988, and although most signature schemes used in practice cannot be proved secure with respect to it, they are all built so that they hopefully fulfil it, e.g., by the inclusion of hash functions or redundancy to counter active attacks.Recently, however, several signature schemes with new security properties have been presented. Most of them exist in several variants, and some of them pay for the new properties with restrictions in other respects, whose relation is not always clear. Obviously, these new properties need definitions and some classification. Unfortunately, however, none of the new schemes is covered by the definition mentioned above. Hence the new properties cannot be defined as additions, but each new type of scheme needs a new definition from scratch, although there are similarities between the definitions. This is unsatisfactory.This paper presents (an overview of) a general definition of digital signature schemes that covers all known schemes, and hopefully all that might be invented in future. Additional properties of special types of schemes are then presented in an orthogonal way, so that existing schemes can be classified systematically. It turns out that signature schemes are best defined by a separation of service, structure, and degree of security, with a service specification in temporal logic. Several parts of such a definition can easily be reused for general definitions of other classes of cryptologic schemes.Relations to secure multi-party protocols and logics of authentication are discussed.
Computing selected eigenvalues of sparse unsymmetric matrices using subspace iteration
Authors: I. S. Duff, J. A. Scott
Venue: ACM Transactions on Mathematical Software (TOMS) (1993)

This paper discusses the design and development of a code to calculate the eigenvalues of a large sparse real unsymmetric matrix that are the rightmost, leftmost, or are of the largest modulus. A subspace iteration algorithm is used to compute a sequence of sets of vectors that converge to an orthonormal basis for the invariant subspace corresponding to the required eigenvalues. This algorithm is combined with Chebychev acceleration if the rightmost or leftmost eigenvalues are sought, or if the eigenvalues of largest modulus are known to be the rightmost or leftmost eigenvalues. An option exists for computing the corresponding eigenvectors. The code does not need the matrix explicitly since it only requires the user to multiply sets of vectors by the matrix. Sophisticated and novel iteration controls, stopping criteria, and restart facilities are provided. The code is shown to be efficient and competitive on a range of test problems.
Fbufs: a high-bandwidth cross-domain transfer facility
Authors: Peter Druschel, Larry L. Peterson
Venue: Proceedings of the fourteenth ACM symposium on Operating systems principles (1994)

We have designed and implemented a new operating system facility for I/O buffer management and data transferacross protection domain boundaries on shared memory machines. This facility, called fast buffers (fbufs), combines virtual page remapping with shared virtual memory, and exploits locality in I/O traffic to achieve high throughput without compromising protection, security, or modularity. goal is to help deliver the high bandwidth afforded by emerging high-speed networks to user-level processes, both in monolithic and microkernel-based operating systems.This paper outlines the requirements for a cross-domain transfer facility, describes the design of the fbuf mechanism that meets these requirements, and experimentally quantifies the impact of fbufs on network performance.
An interactive debugging tool for C based on dynamic slicing and dicing
Authors: M. Samadzadeh, W. Wichaipanitch
Venue: Proceedings of the 1993 ACM conference on Computer science (1993)

Static Program Slicing has gained wide recognition in both academic and practical arenas. Several debugging tools have been developed that utilize static program slicing. Dynamic slicing has also gained considerable popularity in recent years. Due to the several advantages of dynamic slicing over static slicing, the objective of this work was to develop a debugging tool for C programs, called C-Debug, using dynamic slicing and dicing techniques. This paper reports the design considerations of C-Debug and the data structures used in the implementation of C-Debug. Based on the usage experiments with the C-Debug debugging tool, limitations and possible future enhancements are also outlined.
A discussion of special characteristics for software package development life cycle models
Authors: Erran Carmel
Venue: ACM SIGSOFT Software Engineering Notes (1993)

Software package development (SPD) is playing an increasingly important role in the software market. Traditionally, most software has been developed for custom purposes which differs somewhat from SPD in some Life Cycle Model (LCM) characteristics. Five special characteristics for SPD are discussed: accommodating the unknown user, formalizing customer requirements, supporting multiple platforms and versions, facilitating speed of development and reacting to market pressures, and incorporating risk minimization.
Index support for rule activation
Authors: David A. Brant, Daniel P. Miranker
Venue: Proceedings of the 1993 ACM SIGMOD international conference on Management of data (1993)

Integrated rule and database systems are quickly moving from the research laboratory into commercial systems. However, the current generation of prototypes are designed to work with small rule sets involving limited inferencing. The problem of supporting large complex rule programs within database management systems still presents significant challenges. The basis for many of these challenges is providing support for rule activation. Rule activation is defined as the process of determining which rules are satisfied and what data satisfies them. In this paper we present performance results for the DATEX database rule system and its novel indexing technique for supporting rule activation. Our approach assumes that both the rule program and the database must be optimized synergistically. However, as an experimental result we have determined that DATEX requires very few changes to a standard DBMS environment, and we argue that these changes are reasonable for the problems being solved. Based on the performance of DATEX we believe we have demonstrated a satisfactory solution to the rule activation problem for complex rule programs operating within a database system.
Iterative Consistency: A Concept for the Solution of Singular Systems of Linear Equations
Authors: M. Hanke
Venue: SIAM Journal on Matrix Analysis and Applications (1994)

The authors present a fast procedure for computing a "modified" triangular factorization of Hankel, quasi-Hankel (matrices congruent in a certain sense to Hankel matrices) and sign-modified quasi-Hankel (products of quasi-Hankel and signature matrices) matrices. A fast procedure for computing inverse of Hankel and quasi-Hankel matrices is also presented. A modified triangular factorization is an $LDL*$ factorization, where $L$ is lower triangular with unit diagonal entries and $D$ is a block diagonal matrix with possibly varying block sizes. Only matrices with all leading minors nonzero, often called strongly regular, will always have a purely diagonal and nonsingular $D$ matrix. The matrices studied in this paper have diagonal blocks with a particular Hankel-(like) structure. The algorithms presented here are obtained by extending a generating function approach of Lev-Ari and Kailath for matrices with a generalized displacement structure. A particular application of the results is a fast method of computing the rank profile and inertia of the matrices involved.
Equivalence, reversibility, symmetry and concavity properties in fork-join queuing networks with blocking
Authors: Yves Dallery, Zhen Liu, Don Towsley
Venue: Journal of the ACM (JACM) (1994)

In this paper, we study quantitative as well as qualitative properties of Fork-Join Queuing Networks with Blocking (FJQN/Bs). Specifically, we prove results regarding the equivalence of the behavior of a FJQN/B and that of its duals and a strongly connected marked graph. In addition, we obtain general conditions that must be satisfied by the service times to guarantee the existence of a long-term throughput and its independence on the initial configuration. We also establish conditions under which the reverse of a FJQN/B has the same throughput as the original network. By combining the equivalence result for duals and the reversibility result, we establish a symmetry property for the throughput of a FJQN/B. Last, we establish that the throughput is a concave function of the buffer sizes and the initial marking, provided that the service times are mutually independent random variables belonging to the class of PERT distributions that includes the Erlang distributions. This last result coupled with the symmetry property can be used to identify the initial configuration that maximizes the long-term throughput in closed series-parallel networks.
Vague text compression
Authors: Andrew Davison
Venue: ACM SIGACT News (1993)

A new approach to the "lossy" compression of text is described, based on the computational benefits of reading handwritten text, as opposed to text set in a more formal typographical style. Specifically, a new class of fonts, called vague fonts, are proposed which encode the vagueness of handwriting. Text written using a vague font can be compressed to a much greater degree than the same text represented in a conventional font.
Imaging the Universe at Radio Wavelengths
Authors: Richard M. Crutcher
Venue: IEEE Computational Science Engineering (1994)

Computerized image processing is crucial for the large arrays of radio telescopes that are advancing astronomy. A new project will help relieve the computational bottleneck that hinders this field. The National Science Foundation (NSF) has funded a 5-year Grand Challenge High-Performance Computing and Communications project to (a) allow astronomers to use upgraded NSF supercomputers; (b) develop network links to widely-used observatories; and (c) develop digital data archives over national high-speed networks. We plan to prototype the next generation of astronomical telescope systems. These will be remotely located telescopes connected by high-speed networks to very high performance, scalable-architecture computers and online data archives. Astronomers will access these systems via gigabit-per-second networks, and use advanced visualization tools to comprehend and analyze the very large multidimensional images being generated.
A compaction algorithm for non-convex polygons and its application
Authors: Zhenyu Li, Victor Milenkovic
Venue: Proceedings of the ninth annual symposium on Computational geometry (1993)

Given a two dimensional, non-overlapping layout of convex and non-convex polygons, compaction can be thought of as simulating the motion of the polygons as a result of applied &ldquo;forces.&rdquo; Compaction can be modeled as a motion of the polygons that reduces the value of some linear functional on their positions. Optimal compaction, planning a motion that finds the global minimum reachable value, is shown to be NP-complete. We give a compaction algorithm that finds a local minimum by direct calculation of the new polygon positions via linear programming. We also consider the related problem of separating overlapping polygons using a minimal amount of motion and show it to be NP-complete. A locally optimum version of this problem is solved using a slight modification of the compaction algorithm. The compaction algorithm and the separation algorithm have been applied to marker making: the task of packing polygonal pieces on a sheet of cloth of fixed width so that total length is minimized. The compaction algorithm has improved cloth utilization of human generated pants markers. The separation algorithm together with a database of human-generated markers can be used to automatically generate markers that are close to human performance.
Improving Software Maintenance at Martin Marietta
Authors: Joel Henry, Sallie Henry, Dennis Kafura, Lance Matheson
Venue: IEEE Software (1994)

Using data collected throughout a major project, the authors apply common statistical methods to quantitatively assess and evaluate improvements in a large contractor's software-maintenance process. Results show where improvements are needed; examining the change in statistical results lets you quantitatively evaluate the effectiveness of the improvements. We selected a process-assessment methodology developed by J.E. Henry (1993) that follows Total Quality Management principles and is based on Watts Humphrey's Process Maturity Framework. It lets you use a process modeling technique based on control-flow diagrams to define an organization's maintenance process. After collecting process and product data throughout the maintenance process, you analyze it using parametric and nonparametric statistical techniques. The statistical-analysis results and the process model help you assess and guide improvements in the organization's maintenance process. The method uses common statistical tests to quantify relationships among maintenance activities and process and product characteristics. The relationships, in turn, tell you more about the maintenance process and how requirements changes affect the product.
No assembly required: compiling standard ML to C
Authors: David Tarditi, Peter Lee, Anurag Acharya
Venue: ACM Letters on Programming Languages and Systems (LOPLAS) (1992)

C has been used as a portable target language for implementing languages like Standard ML and Scheme. Previous efforts at compiling these languages to C have produced efficient code, but have compromised on portability and proper tail recursion. We show how to compile Standard ML to C wihout making such compromises. The compilation technique is based on converting Standard ML to a continuation-passing style &lgr;-calculus intermediate language and then compiling this language to C. The code generated by this compiler achieves an execution speed that is about a factor of two slower than that generated by a native code compiler. The compiler generates highly portable code, yet still supports advanced features like garbage collection and first-class continuations. We analyze the performance and determine the aspects of the compilation method that lead to the observed slowdown. We also suggest changes to C compilers that would better support such compilation methods.
Transitive closure algorithms based on graph traversal
Authors: Yannis Ioannidis, Raghu Ramakrishnan, Linda Winger
Venue: ACM Transactions on Database Systems (TODS) (1993)

Several graph-based algorithms have been proposed in the literature to compute the transitive closure of a directed graph. We develop two new algorithms (Basic_TC and Gobal_DFTC) and compare the performance of their implementations in a disk-based environment with a well-known graph-based algorithm proposed by Schmitz. Our algorithms use depth-first search to traverse a graph and a technique called marking to avoid processing some of the arcs in the graph. They compute the closure by processing nodes in reverse topological order, building descendent sets by adding the descendent sets of children. While the details of these algorithms differ considerably, one important difference among them is the time at which descendent set additions are performed. Basic_TC, results in superior performance. The first reason is that early additions result in larger descendent set sizes on the average over the duration of the execution, thereby causing more I/O; very often this turns out to more than offset the gains of not having to fetch certain sets again to add them. The second reason is that information collected in the first pass can be used to apply several optimizations in the second pass. To the extent possible, we also adapt these algorithms to perform path computations. Again, our performance comparison confirms the trends seen in reachability queries. Taken in conjunction with another performance study our results indicate that all graph-based algorithms significantly outperform other types of algorithms such as Seminaive and Warren.
A review of exploitation of AND-parallelism and combined AND/OR-parallelism in logic programs
Authors: Kang Zhang
Venue: ACM SIGPLAN Notices (1994)

Logic programs provide many opportunities for parallel execution. Among different forms of parallelism found in logic programs, AND-parallelism and OR-parallelism have shown to be most effective in speeding up the execution of logic programs. This paper offers a review of major activities in exploiting AND-parallelism and combined AND/OR-parallelism. Full version of this paper (23 pages) can be retrieved through anonymous ftp from ftp.mpce.mq.edu.au.
Using Buchbergers algorithm in invariant theory
Authors: Manfred Göbel
Venue: ACM SIGSAM Bulletin (1993)

This paper shows how Groebner bases theory could be used in invariant theory. It presents algorithms for representation, basis-construction and -test for the ring InvK/Gn of Gn-invariant polynomials over the field K for any given group Gn of permutations.
Testing object-oriented software (abstract)
Authors: Edward Berard
Venue: ACM SIGPLAN OOPS Messenger (1993)

Testing Object-Oriented Software Edward Berard, Berard Software Engineering Testing of object-oriented software is just as important as testing non-object-oriented software, but the process is fundamentally different because of such factors as information hiding, encapsulation, and inheritance. This tutorial teaches you the terms and concepts of testing software in general, and object-oriented software in particular; how to apply a number of different testing techniques to object-oriented software; how to construct test cases; and an appreciation of what is involved in planning a successful software testing effort. The testing techniques that are covered include both white-box testing such as basis path testing and coverage testing, and black-box testing techniques such as equivalence class partitioning and boundary value analysis. This course is designed for those with experience in object-oriented software engineering who would like to follow a more rigorous approach to testing.
Reverse If-Conversion
Authors: Nancy J. Warter, Scott A. Mahlke, Wen-Mei W. Hwu, B. Ramakrishna Rau
Venue: Proceedings of the ACM SIGPLAN 1993 conference on Programming language design and implementation (1993)

In this paper we present a set of isomorphic control transformations that allow the compiler to apply local scheduling techniques to acyclic subgraphs of the control flow graph. Thus, the code motion complexities of global scheduling are eliminated. This approach relies on a new technique, Reverse If-Conversion (RIC), that transforms scheduled If-Converted code back to the control flow graph representation. This paper presents the predicate internal representation, the algorithms for RIC, and the correctness of RIC. In addition, the scheduling issues are addressed and an application to software pipelining is presented.
The management of end-user computing: status and directions
Authors: James C. Brancheau, Carol V. Brown
Venue: ACM Computing Surveys (CSUR) (1993)

The development of computing applications by the people who have direct need for them in their work has become commonplace. During the 1980s, development of applications by &ldquo;end users&rdquo; accelerated and became a key management and research concern. Known as &ldquo;end-user computing,&rdquo; the phenomena and research associated with this trend cross a variety of disciplines. This article critically surveys the published literature on end-user computing (EUC) management according to a comprehensive research model. The article introduces the EUC management research model, identifies prior research contributions, and offers guideline for the future. The focal points of the model are two EUC management components which represent two different levels of theorizing found in the literature. The first level focuses on the organization factors of strategy, technology, and management action. The second level focuses on the individual factors of end user, task, tool, and end-user action. The remainder of the model includes factors typically investigated as the antecedents (context) and consequences (outcomes) of EUC. More than 90 English-language articles published from 1983-1990 are mapped into the model. Specific variables for each factor are identified; research streams are interpreted; findings are synthesized; and gaps in our knowledge are highlighted. We then raise a number of substantive and methodological issues that need to be addressed and suggest two themes we envision as important for EUC management research in the 1990s: EUC as an extension of organizational computing and EUC as a social learning phenomenon. Guidance is offered for using these theme to inform future research.
A deterministic linear time algorithm for geometric separators and its applications
Authors: David Eppstein, Gary L. Miller, Shang-Hua Teng
Venue: Proceedings of the ninth annual symposium on Computational geometry (1993)

We give a deterministic linear time algorithm for finding a small cost sphere separator of a k-ply neighborhood system &Fgr; in any fixed dimension, where a k-ply neighborhood system in Rd is a collection of n balls such that no points in the space is covered by more than k balls. The sphere separator intersects at most Ok1dnd-1 d balls of &Fgr; and it divides the remaining of &Fgr; into two parts: those in the interior and those in the exterior of the sphere, respectively, so that the larger part contains at most &dgr;n balls d+1d+2<d< 1 . This result improves the 0(n2) time deterministic algorithm of Miller and Teng [29] and answers a major algorithmic open question posed by Miller, Teng, Thurston and Vavasis [23,25]. The deterministic algorithm hinges on the use of a new method for deriving the separator property of neighborhood systems. Using this algorithm, we devise an O(kn + n log n) time deterministic algorithm for computing the intersection graph of a k-ply neighborhood system. We give an O(n log n) time algorithm for constructing a linear space, O(log n) query time search structure for a geometric query problem associated with k-ply neighborhood systems, and we use this data structure in an algorithm for approximating the value of k within a constant factor in time O(n log n). We also develop a deterministic linear time algorithm for finding an Ok1dnd-1 d -separator for a k-nearest neighborhood graph in d dimensions.
Cooperative acceleration: robust conservative distributed discrete event simulation
Authors: T. D. Blanchard, T. W. Lake, S. J. Turner
Venue: Proceedings of the eighth workshop on Parallel and distributed simulation (1994)

Robustness of the simulation mechanism is a requirement for acceptability of distributed simulation environments. We consider complex and erratic distributed conservative simulations, using colliding pucks as a guiding example. A new mechanism is introduced which allows logical processes to cooperate locally and advance. Advance is made through the collective selection of the next event in a group of logical processes. The algorithm demonstrates scalability through the locality of its determination. A description and proof of correctness is given. The effectiveness of the cooperative acceleration mechanism is illustrated with measurements on road traffic and colliding pucks simulations.