ppxscal/embedding_network huggingface dataset:
The effects of initial population in genetic search for time constrained traveling salesman problems
Authors: Cheng-Hong Yang, Kendall E. Nygard
Venue: Proceedings of the 1993 ACM conference on Computer science (1993)

We describe the application of Genetic Algorithms to the traveling salesman problem with time windows. A new type of crossover operator, called edge-type crossover, with a heuristically selected initial population, is used in the genetic search. When compared with alternative methods from the literature, experiments indicate that the heuristic initialization speeds the genetic search process.
Fankestein's insects (abstract)
Authors: Jonathan Mills
Venue: Proceedings of the 1993 ACM conference on Computer science (1993)

Research aimed at correcting words in text has focussed on three progressively more difficult problems: 1) non-word error detection; 2) isolated-word error correction; and 3) contextdependent word correction. In response to the first problem, efficient pattern matching and n-gram analysis techniques have been developed for detecting strings that do not appear in a given word list. In response to the second problem, a variety of general and application-specific spelling correction techniques have been developed. Some of them were based on detailed studies of spelling error patterns. In response to the third problem, a few experiments using natural language processing tools or statis tical language models have been carried out. This article surveys documented findings on spelling error correction techniques, reviews the state of the art of context-dependent word correction techniques, and discusses research issues related to all three areas of automatic error correction in text. (The Article on which the Talk was based appeared in the December 1992 Issue of Computing Surveys) 515
A taxonomy of complexity classes of functions
Authors: Alan L. Selman
Venue: Journal of Computer and System Sciences (1994)

This paper comprises a systematic comparison of several complexity classes of functions that are computed nondeterministically in polynomial time or with an oracle in NP. There are three components to this work:*A taxonomy is presented that demonstrates all known inclusion relations of these classes. For (nearly) each inclusion that is not shown to hold, evidence is presented to indicate that the inclusion is false. As an example, consider FewPF, the class of multivalued functions that are nondeterministically computable in polynomial time such that for each x there is a polyomial bound on the number of distinct output values of f(x). We show that FewPF @?"c PF^N^P"t"t. However, we show PF^N^P"t"t @? FewPF if and only if NP = co-NP, and thus PF^N^P"t"t @? FewPF is likely to be false. *Whereas it is known that P^N^P(O(log n)) = P^N^P"t"t @? P^N^P, we show that PF^N^P(O(log n)) = PF^N^P"t"t implies P = FewP and R = NP. Also, we show that PF^N^P"t"t = PF^N^P if and only if P^N^P"t"t = P^N^P. *We show that if every nondeterministic polynomial-time multivalued function has a single-valued nondeterministic refinement (equivalently, if every honest function that is computable in polynomial-time can be inverted by a single-valued nondeterministic function), then there exists a disjoint pair of NP-complete sets such that every separator is NP-hard. The latter is a previously studied open problem that is closely related to investigations on promise problems. This result motivates a study of reductions between partial multivalued functions.
An analysis model on nonblocking multirate broadcast networks
Authors: Yuanyuan Yang
Venue: Proceedings of the 8th international conference on Supercomputing (1994)

Designing efficient interconnection networks with powerful connecting capability remains a key issue to parallel and distributed computing systems. Many progresses have been made in nonblocking broadcast networks which can realize all one-to-many connections between any network input port and a set of output ports without any disturbance (that is, rearrangement) of other existing connections. However, all results obtained so far for broadcast networks are for the circuit switching or single rate communication model. Meanwhile, there have been growing interests in large networks operated in a packet switching manner. This type of network can be modeled as a multirate network wherein a single link can be shared by multiple connections with arbitrary data rate. Previous work has been done on the blocking behavior of multirate one-to-one connection or permutation networks. However, yet very little is known about the behavior of multirate one-to-many connection or broadcast networks. In this paper, we will determine nonblocking conditions for v(m,n1,r1,n2,r2) networks under which any multirate broadcast connection request from a network input port to a set of network output ports can be satisfied without any disturbance of the existing connection in the network. Our results show that more general multirate broadcast networks can be constructed in the same order of hardware complexity as the best available single rate nonblocking broadcast networks. Our proofs for the theorems also imply an efficient routing algorithm for such networks. Multirate broadcast networks can provide strong support for parallel and distributed computing systems which require to broadcast multirate data in a random-access environment.
When floating-point addition isn't commutative
Authors: Fred Ris, Ed Barkmeyer, Craig Schaffert, Peter Farkas
Venue: ACM SIGNUM Newsletter (1993)

In this note, the symbols "+", "x", and "=" have their mathematical meanings; the symbols " oplus;", " otimes;", and " rarr;" denote floating-point addition, multiplication and assignment respectively. Informally, T rarr; A oplus; B implies T = round (A+B), T rarr; A otimes; B implies T = round (AB), and T rarr; AB oplus; C implies T = round (AxB + C).
Towards a semantics of desires (abstract)
Authors: George Kiss, Han Reichgelt
Venue: ACM SIGOIS Bulletin (1992)

Research in Distributed Artificial Intelligence (DAI) often considers the problem of how best to utilize multiple automated agents to accomplish a given task. A canonical problem, the Pursuit Problem (1), has been suggested as a useful tool for evaluating alternative approaches to the distribution of knowledge and control among intelligent, cooperative problem-solvers. Work on the Pursuit Problem has been carried out by several researchers; for example, Stephens and Merx (16, 171 compare alternative approaches to solving the problem.In [5], a game theoretic model was proposed for DAI in which each agent works for his own selfish goals. In this paper, we suggest a method for solving the Pursuit Problem using game theoretic techniques, by incorporating the global goal of a group of agents into their local interests. Although applied to the Pursuit Problem, the technique has wider applicability throughout DAI. We present the results of a simulation of the game theory model for the Pursuit Problem, and compare results to those of Stephens and Merx's models.
A distributed queueing random access protocol for a broadcast channel
Authors: Wenxin Xu, Graham Campbell
Venue: Conference proceedings on Communications architectures, protocols and applications (1993)

For decades there has been a search for a multiple access protocol for a broadcast channel that would provide a performance that approached that of the ideal M/D/1 queue. This ideal performance would provide immediate access at light loads and then seamlessly move to a reservation system at high offered loads. DQRAP (distributed queueing random access protocol) provides a performance which approaches this ideal. Furthermore it is accomplished using as few as three control minislots which suggests that, aside from establishing new theoretical bounds, DQRAP will be of great practical value.DQRAP requires that channel time be divided into slots each of which consists of one data slot and m control minislots, and that each station maintain two common distributed queues. One queue is called the data transmission queue, or simply TQ, used to organize the order of data transmission, the other queue is the collision resolution queue, or simply RQ, which is used to resolve the collisions and to prevent collisions by new arrivals. The protocol includes data transmission rules, request transmission rules and queuing discipline rules. Modelling and simulation indicate that DQRAP, using as few as 3 minislots, achieves a performance level which approaches that of a hypothetical perfect scheduling protocol, i.e., the M/D/1 system, with respect to throughput and delay. DQRAP could prove useful in packet radio, satellite, broadband cable, cellular voice, WAN, and passive optical networks.
A parallel programming environment supporting multiple data-parallel modules
Authors: Bradley K. Seevers, Michael J. Quinn, Philip J. Hatcher
Venue: ACM SIGPLAN Notices (1993)

We describe a system that allows programmers to take advantage of both control and data parallelism through multiple data-parallel modules. This system extends C-type stream I/O to include inter-module communication channels. The programmer writes each module separately, then develops a specification that instructs the system how to connect the modules together. Our current system extends the Dataparallel C language and runs on the Intel iWarp computing system.
Triangulations in CAGD
Authors: Larry L. Schumaker
Venue: IEEE Computer Graphics and Applications (1993)

Triangulations, which play an important role in approximation theory, finite-element methods, numerical analysis, and computer-aided geometric design (CAGD), are defined. Triangulations in the plane, in space, and on the surface of a sphere are discussed. The storing and construction of triangulations are also discussed.
Ada real-time systems and basic priority inheritance
Authors: Loïc Briand
Venue: ACM SIGAda Ada Letters (1994)

The Rate Monotonic Scheduling theory is often presented as the ultimate means for improving dramatically and easily the schedulability of Ada Real-Time systems. To assess its practical impact on Real-Time systems, the behavior of a hard-deadline simulated task set is statstically analyzed in different contexts of scheduling (standard Ada FIFO scheduling or basic priority inheritance) and priority allocation (higher priority to the shorter deadline or to the shorter period).
An Error Model for Swarztrauber's Parallel Tridiagonal Equation Solver
Authors: Nai-Kuan Tsao
Venue: SIAM Journal on Matrix Analysis and Applications (1994)

Error models for two algorithms based on Cramer's rule are given for tridiagonal systems. The results show that if the exact $x_i$ of the solution vector $x$ is expressed as $\det p/ \det q$ where $p$ and $q$ are matrices formed from the original coefficient matrix and the right-hand side vector, then the computed $x_i$ can be expressed as $\det \hat{p}/ \det \hat{q}$, where $\det \hat{p}$ and $\det \hat{q}$ are perturbed $\det p$ and $\det q$, respectively, using either the parallel or the sequential algorithm. The relative error of each product in the determinantal expansion of $\det \hat{p}$ and $\det \hat{q}$ can also be bounded easily.
Chores: enhanced run-time support for shared-memory parallel computing
Authors: Derek L. Eager, John Jahorjan
Venue: ACM Transactions on Computer Systems (TOCS) (1993)

Parallel computing is increasingly important in the solution of large-scale numerical problems. The difficulty of efficiently hand-coding parallelism, and the limitations of parallelizing compilers, have nonetheless restricted its use by scientific programmers. In this paper we propose a new paradigm, chores, for the run-time support of parallel computing on shared-memory multiprocessors. We consider specifically uniform memory access shared-memory environments, although the chore paradigm should also be appropriate for use within the clusters of a large-scale nonuniform memory access machine. We argue that chore systems attain both the high efficiency of compiler approaches for the common case of data parallelism, and the flexibility and performance of user-level thread approaches for functional parallelism. These benefits are achieved within a single, simple conceptual model that almost entirely relieves the programmer and compiler from concerns of granularity, scheduling, and enforcement of synchronization constraints. Measurements of a prototype implementation demonstrate that the chore model can be supported more efficiently than can traditional approaches to either data or functional parallelism alone.
Toward parallel mathematical software for elliptic partial differential equations
Authors: Calvin J. Ribbens, Layne T. Watson, Colin Desa
Venue: ACM Transactions on Mathematical Software (TOMS) (1993)

Three approaches to parallelizing important components of the mathematical software package ELLPACK are considered: an explicit approach using compiler directives available only on the target machine, an automatic approach using an optimizing and parallelizing precompiler, and a two-level approach based on extensive use of a set of low level computational kernels. The focus is on shared memory architectures. Each approach to parallelization is described in detail, along with a discussion of the effort involved. Performance on a test problem, using up to sixteen processors of a Sequent Symmetry S81, is reported and discussed. Implications for the parallelization of a broad class of mathematical software are drawn.
Automatic indexing based on Bayesian inference networks
Authors: Kostas Tzeras, Stephan Hartmann
Venue: Proceedings of the 16th annual international ACM SIGIR conference on Research and development in information retrieval (1993)

In this paper, a Bayesian inference network model for automatic indexing with index terms (descriptors) from a prescribed vocabulary is presented. It requires an indexing dictionary with rules mapping terms of the respective subject field onto descriptors and inverted lists for terms occuring in a set of documents of the subject field and descriptors manually assigned to these documents. The indexing dictionary can be derived automatically from a set of manually indexed documents. An application of the network model is described, followed by an indexing example and some experimental results about the indexing performance of the network model.
Detection and recovery of endangered variables caused by instruction scheduling
Authors: Ali-Reza Adl-Tabatabai, Thomas Gross
Venue: Proceedings of the ACM SIGPLAN 1993 conference on Programming language design and implementation (1993)

Instruction scheduling re-orders and interleaves instruction sequences from different source statements. This impacts the task of a symbolic debugger, which attempts to present the user a picture of program execution that matches the source program. At a breakpoint B, if the value in the run-time location of a variable V may not correspond to the value the user expects V to have, then this variable is endangered at B. This paper describes an approach to detecting and recovering endangered variables caused by instruction scheduling. We measure the effects of instruction scheduling on a symbolic debugger's ability to recover source values at a breakpoint. This paper reports measurements for three C programs from the SPEC suite and a collection of programs from the Numerical Recipes, which have been compiled with a variant of a commercial C compiler.
Strong Hall Matrices
Authors: Richard A. Brualdi, Bryan L. Shader
Venue: SIAM Journal on Matrix Analysis and Applications (1994)

The authors develop an inductive structure for nonsquare strong Hall matrices that is quite analogous to the well-known inductive structure of square strong Hall (i.e., fully indecomposable) matrices. Other properties of strong Hall matrices are also discussed.
An Investigation of the Therac-25 Accidents
Authors: N. G. Leveson, C. S. Turner
Venue: Computer (1993)

Between June 1985 and January 1987, the Therac-25 medical electron accelerator was involved in six massive radiation overdoses. As a result, several people died and others were seriously injured. A detailed investigation of the factors involved in the software-related overdoses and attempts by users, manufacturers, and government agencies to deal with the accidents is presented. The authors demonstrate the complex nature of accidents and the need to investigate all aspects of system development and operation in order to prevent future accidents. The authors also present some lessons learned in terms of system engineering, software engineering, and government regulation of safety-critical systems containing software components.
Interprocedural modification side effect analysis with pointer aliasing
Authors: William Landi, Barbara G. Ryder, Sean Zhang
Venue: ACM SIGPLAN Notices (1993)

We present a new interprocedural modification side effects algorithm for C programs, that can discern side effects through general-purpose pointer usage. Ours is the first complete design and implementation of such an algorithm. Preliminary performance findings support the practicality of the technique, which is based on our previous approximation algorithm for pointer aliases [LR92]. Each indirect store through a pointer variable is found, on average, to correspond to a store into 1.2 locations. This indicates that our program-point-specific pointer aliasing information is quite precise when used to determine the effects of these stores.
Normal forms and conservative properties for query languages over collection types
Authors: Limsoon Wong
Venue: Proceedings of the twelfth ACM SIGACT-SIGMOD-SIGART symposium on Principles of database systems (1993)

Strong normalization results are obtained for a general language for collection types. An induced normal form for sets and bags is then used to show that the class of functions whose input has height (that is, the maximal depth of nestings of sets/bags/lists in the complex object) at most i and output has height at most o definable in a nested relational query language without powerset operator is independent of the height of intermediate expressions used. Our proof holds regardless of whether the language is used for querying sets, bags, or lists, even in the presence of variant types. Moreover, the normal forms are useful in a general approach to query optimization. Paredaens and Van Gucht proved a similar result for the special case when i = o = 1. Their result is complemented by Hull and Su who demonstrated the failure of independence when powerset operator is present and i = o = 1. The theorem of Hull and Su was generalized to all i and o by Grumbach and Vianu. Our result generalizes Paredaens and Van Gucht's to all i and o, providing a counterpart to the theorem of Grumbach and Vianu.
Mapping a complex temporal problem into a combination of static and dynamic neural networks
Authors: Thierry Catfolis
Venue: ACM SIGART Bulletin (1994)

Until recently, time related artificial intelligence problems were considered difficult to tackle, and the element time was often eliminated from the core problem. Only during the last decades, researchers (Decortis amp; Cacciabue, [4]; Klopf amp; Morgan, [7]) started to explore the importance of time dependencies in artificial intelligence systems. Two different methods - 'time windows' or 'time buffers' and 'dynamic systems' - were experimented and improved in classic artificial intelligence problems like expert systems (Malkoff, [9]).The next step was to apply these two methods to artificial neural network algorithms. Initially, these algorithms (like back-propagation) used a 'time window' approach (Levin et al., [8]; Chakraborty et al., [3]) but recently dynamic network algorithms were developed (Hirsch, [6]; Reiss amp; Taylor, [10]; Schmidhuber, [13]; Williams amp; Zipser, [14]).We explain the advantages of these algorithms and the problems that occur due to their computational requirements. We introduce a method for lowering this requirement by splitting a temporal task into a (smaller) temporal part and a static or non-temporal part. By doing so we obtain the advantages of both methods: the inherent implementation of unknown time dependencies with the dynamic neural network and the low computational effort of the static neural network. We demonstrate this approach on a simple diagnosis problem.
The F3 reuse environment for requirements engineering
Authors: Silvana Castano, Valeria De Antonellis
Venue: ACM SIGSOFT Software Engineering Notes (1994)

The F3 reuse environment for supporting the Requirements Engineering process is illustrated and discussed in the paper. In particular, an overview of our approach for building reusable components from existing requirements and for exploiting them in the development of new applications is presented. The approach is based on classification techniques to facilitate extraction of reusable components, and on transformation techniques to support composition of reusable components.
Inferring constraints from multiple snapshots
Authors: David Kurlander, Steven Feiner
Venue: ACM Transactions on Graphics (TOG) (1993)

Many graphic tasks, such as the manipulation of graphical objects and the construction of user-interface widgets, can be facilitated by geometric constraints. However, the difficulty of specifying constraints by traditional methods forms a barrier to their widespread use. In order to make constraints easier to declare, we have developed a method of specifying constraints implicitly, through multiple examples. Snapshots are taken of an initial scene configuration, and one or more additional snapshots are taken after the scene has been edited into other valid configurations. The constraints that are satisfied in all of the snapshots are then applied to the scene objects. We discuss an efficient algorithm for inferring constraints from multiple snapshots. The algorithm has been incorporated into the Chimera editor, and several examples of its use are discussed.
The identification of important concepts in highly structured technical papers
Authors: Chris D. Paice, Paul A. Jones
Venue: Proceedings of the 16th annual international ACM SIGIR conference on Research and development in information retrieval (1993)

Automatic abstracting, typically based on extraction of important sentences from a text, has been treated as a largely separate task from automatic indexing. This paper describes an approach in which the indexing and abstracting tasks are effectively combined. It is applicable to highly structured empirical research papers, whose content can be organised using a semantic frame. During a scan of a source text, stylistic clues and constructs are used for extracting candidate fillers for the various slots in the frame. Subsequently, an actual concept name is chosen for each slot by comparing the various candidates and their weights.
Augmented encrypted key exchange: a password-based protocol secure against dictionary attacks and password file compromise
Authors: Steven M. Bellovin, Michael Merritt
Venue: Proceedings of the 1st ACM conference on Computer and communications security (1993)

The encrypted key exchange (EKE) protocol is augmented so that hosts do not store cleartext passwords. Consequently, adversaries who obtain the one-way encrypted password file may (i) successfully mimic (spoof) the host to the user, and (ii) mount dictionary attacks against the encrypted passwords, but cannot mimic the user to the host. Moreover, the important security properties of EKE are preserved&mdash;an active network attacker obtains insufficient information to mount dictionary attacks. Two ways to accomplish this are shown, one using digital signatures and one that relies on a family of commutative one-way functions.