ppxscal/embedding_network huggingface dataset:
Adding liveness properties to coupled finite-state machines
Authors: S. Aggarwal, C. Courcoubetis, P. Wolper
Venue: ACM Transactions on Programming Languages and Systems (TOPLAS) (1990)

Informal specifications of protocols are often imprecise and incomplete and are usually not sufficient to ensure the correctness of even very simple protocols. Consequently, formal specification methods, such as finite-state models, are increasingly being used. The selection/resolution (S/R) model is a finite-state model with a powerful communication mechanism that makes it easy to describe complex protocols as a collection of simple finite-state machines. A software environment, called SPANNER, has been developed to specify and analyze protocols specified with the S/R model. SPANNER provides the facility to compute the joint behavior of a number of finite-state machines and to check if the &ldquo;product&rdquo; machine has inaccessible states, states corresponding to deadlocks, and loops corresponding to livelocks. So far, however, SPANNER has had no facility to systematically deal with liveness conditions. For example, one might wish to specify that, although a communication channel is unreliable, a message will get through if it is sent infinitely often, and to check that the infinite behavior of the protocol viewed as an infinite sequence will always be in some &ohgr;-regular set (possibly specified in terms of a formula in temporal logic or as an &ohgr;-automata). In this paper we show that with very minor modifications to the implemented system it is possible to substantially extend the type of properties that can be specified and checked by SPANNER. This is done by extending the S/R model to include acceptance conditions found in automatons on infinite words, which permits the incorporation of arbitrary liveness conditions into the model. We show how these extensions can be easily incorporated into SPANNER (and into essentially any finite-state verification system) and how the resulting system is used to automatically verify the correctness of protocols.
On monotone paths among obstacles with applications to planning assemblies
Authors: E. M. Arkin, R. Connelly, J. S. Mitchell
Venue: Proceedings of the fifth annual symposium on Computational geometry (1989)

We study the class of problems associated with the detection and computation of monotone paths among a set of disjoint obstacles. We give an &Ogr;(nE) algorithm for finding a monotone path (if one exists) between two points in the plane in the presence of polygonal obstacles. (Here, E is the size of the visibility graph defined by the n vertices of the obstacles.) If all of the obstacles are convex, we prove that there always exists a monotone path between any two points s and t. We give an &Ogr;(n log n) algorithm for finding such a path for any s and t, after an initial &Ogr;(E + n log n) preprocesing. We introduce the notions of &ldquo;monotone path map&rdquo;, and &ldquo;shortest monotone path map&rdquo; and give algorithms to compute them. We apply our results to a class of separation and assembly problems, yielding polynomial-time algorithms for planning an assembly sequence (based on separations by single translations) of arbitrary polygonal parts in two dimensions.
Organizational issues for user services
Authors: Agelia Velleman
Venue: ACM SIGUCCS Newsletter (1988)

In this session, I'll wear two hats. One hat belongs to a computing administrator who considers global issues in academic computing and their impact on higher education. The second hat belongs to a manager of talented and dedicated technical staff who focus on providing computing services for the community at large. I want to share with you the ways in which I've chosen to reorganize User Services at Cornell to reconcile some of the conflicts that arise when wearing these two hats --- to describe some of the ways in which our new organization is working, as well as some of the ways in which more fine-tuning is required. I'd also like to know whether you think this kind of structure would work at your institution.
The Ballast Methodology for Structured Partial Scan Design
Authors: R. Gupta, M. A. Breuer
Venue: IEEE Transactions on Computers (1990)

An efficient partial scan technique called Ballast (balanced structure scant test) is presented. Scan path storage elements (SPSEs) are selected such that the remainder of the circuit has certain desirable testability properties. A complete test set is obtained using combinatorial automatic test pattern generation (ATPG). Some SPSEs may need to be provided with a HOLD mode; their number is minimized by ordering the registers in the scan path and formatting the test patterns appropriately. This methodology leads to a low area overhead and allows 100% coverage of irredundant faults.
Antialiasing of interlaced video animation
Authors: John Amanatides, Don P. Mitchell
Venue: Proceedings of the 17th annual conference on Computer graphics and interactive techniques (1990)

The production of computer-generated video presents a number of difficulties not encountered with motion pictures. Interlaced scanning and the color subcarrier of NTSC video are responsible for special problems such as interline flicker, and chroma aliasing. As in motion pictures, temporal aliasing is also an issue. A renderer can sample and filter a moving image in an arbitrary manner and is not constrained to simply imitate the behavior of a television camera. This paper explores several different spatiotemporal antialiasing filters and how they affect the quality of video animation.
Measuring the true cost of command selection: techniques and results
Authors: R. F. Dillon, Jeff D. Edey, Jo W. Tombaugh
Venue: Proceedings of the SIGCHI conference on Human factors in computing systems: Empowering people (1990)

A technique that measures the impact of command selection on task time and errors is described. Users were timed while performing a drawing task, then while performing the same task with interpolated command selections. The difference between these times, consisting of both the time to select the command and to resume drawing, is the time cost of command selection. Several interface configurations were evaluated with this method including selected combinations of single mouse, two mice, voice and touch. Touch and voice input resulted in faster command selection times (approximately 1 sec) than any of the mouse conditions (approximately 3 sec).
Fast Base Extension Using a Redundant Modulus in RNS
Authors: P. P. Shenoy, R. Kumaresan
Venue: IEEE Transactions on Computers (1989)

A technique to extend the base of a residue number system (RNS) based on the Chinese remainder theorem (CRT) and the use of a redundant modulus, is proposed. The technique obtains the residue(s) of a given number in the extended moduli without resorting to the traditional mixed-radix conversion (MRC) algorithm. The base extension can be achieved in log/sub 2/n table lookup cycles, where n is the number of moduli in the RNS. The superiority of the technique, compared in terms of latency and hardware requirements to the traditional Szabo-Tanaka method is demonstrated.
Destination tag routing techniques based on a state model for the LADM network
Authors: D. Rau, J. A. B. Fortes, H. J. Siegel
Venue: ACM SIGARCH Computer Architecture News (1988)

A &ldquo;state model&rdquo; is proposed for solving the problem of routing and rerouting messages in the Inverse Augmented Data Manipulator (IADM) network. Using this model, necessary and sufficient conditions for the reroutability of messages are established, and then destination tag schemes are derived. These schemes are simpler, more efficient and require less complex hardware than previously proposed routing schemes. Two destination tag schemes are proposed. For one of the schemes, rerouting is totally transparent to the sender of the message and any blocked link of a given type can be avoided. Compared with previous works that deal with the same type of blockage, the timexspace complexity is reduced from &Ogr;(logN) to &Ogr;(1). For the other scheme, rerouting is possible for any type of link blockage. A universal rerouting algorithm is constructed based on the second scheme, which finds a blockage-free path for any combination of multiple blockages if there exists such a path, and indicates absence of such a path if there exists none. In addition, the state model is used to derive constructively a lower bound on the number of subgraphs which are isomorphic to the Indirect Binary n-Cube network in the IADM network. This knowledge can be used to characterize properties of the IADM networks and for permutation routing in the IADM networks.
An optimal distributed depth-first-search algorithm
Authors: M. B. Sharma, N. K. Mandyam, S. S. Iyangar
Venue: Proceedings of the 17th conference on ACM Annual Computer Science Conference (1989)

This paper presents a new distributed depth-first-search algorithm with communication and time complexities of O(|V|). The algorithm is shown to use 2|V|-2 messages and 2|V|-2 units of time and is shown to be optimal in time and message.
Scan line display of algebraic surfaces
Authors: Thomas W. Sederberg, Alan K. Zundel
Venue: Proceedings of the 16th annual conference on Computer graphics and interactive techniques (1989)

A robust algorithm is presented for scan line display of algebraic surfaces of arbitrary degree and topology. The algorithm correctly displays singularities of any complexity, even those missed by ray tracing or polygonization, and (for surfaces of degree less than eight) offers a significant speed improvement over ray tracing. Antialiasing can generally be accomplished very quickly. In addition to its typical function of shaded raster display, the algorithm is particularly adept at quickly plotting silhouette and intersection curves. A practical use for the algorithm is to display boolean combinations of algebraic half spaces, including blend surfaces.A new polynomial basis is introduced, referred to as the Bernstein pyramid polynomial basis, which enhances numerical stability and which simplifies several computations such as scan planesurface intersection and silhouette detection.
CHI '88 poster session papers and abstracts
Authors: S. M. Evans
Venue: ACM SIGCHI Bulletin (1989)

Interactive Poster Sessions serve as a valuable forum for presenting late-breaking research in computer-human interaction and receiving feedback from an interested body of viewers. The poster sessions held at this year's CHI '88 conference, May 15--19 in Washington, D.C., was no exception.Fifty poster presentations, arranged by five topic areas, were located adjacent to the main conference room. Topic areas included user models, interface designs, interface analysis, tools and techniques for interface design, and CHI doctoral eonsortium participants. All 50 posters were on display for the duration of the conference, giving presenter and viewer ample time for interaction. In addition, all poster presenters were available for interaction during the catered opening reception held on Monday evening, May 16, when several hundred people filed through the display area to review poster exhibits and talk with the presenters.The poster exhibitors covered a range of topics as well as a range of countries, with Canada, Germany, England, Switzerland, and Japan represented in addition to the United States. Thirty-three of the participants were from universities, and 10 had also participated in the doctoral consortium held in conjunction with the conference.Abstracts submitted for the poster session were reviewed by a panel of judges which included Louis Blazy, U.S. Department of Defense; Fred Davis' Jr., Graduate School of Business Administration, The University of Michigan; Jay Elkerton, Department of lndustrial and Operations Engineering, The University of Michigan; Susan Evans, Vector Research, Inc.; and Fred Schott, Aetna Life Insurance Company.Additional abstracts and papers can bejbund in the July and October 1988 issues of the SIGCHI Bulletin.
On maximum flows in polyhedral domains
Authors: J. S. Mitchell
Venue: Proceedings of the fourth annual symposium on Computational geometry (1988)

We introduce a new class of problems concerned with the computation of maximum flows through two-dimensional polyhedral domains. Given a polyhedral space (e.g., a simple polygon with holes), we want to find the maximum &ldquo;flow&rdquo; from a source edge to a sink edge. Flow is defined to be a divergence-free vector field on the interior of the domain, and capacity constraints are specified by giving the maximum magnitude of the flow vector at any point. Strang proved that max flow equals min cut; we address the problem of constructing min cuts and max flows. We give polynomial-time algorithms for maximum flow from a source edge to a sink edge through a simple polygon with uniform capacity constraint (with or without holes), maximum flow through a simple polygon from many sources to many sinks, and maximum flow through weighted polygonal regions. Central to our methodology is the intimate connection between the max-flow problem and its dual, the min-cut problem. We show how the continuous Dijkstra paradigm of solving shortest paths problems corresponds to a continuous version of Berge's algorithm for computation of maximum flow in a planar network.
Heuristic control system for autonomous navigation
Authors: Brouno Delaunoit, Rodolphe Alimenti, Marc Bogaert
Venue: Proceedings of the 1st international conference on Industrial and engineering applications of artificial intelligence and expert systems - Volume 1 (1988)

Autonomous navigation of a mobile robot requires that several problems be solved. These problems can be classified corresponding to their hierarchical level. We have defined four levels including, from top to bottom: communication with host (human or computer), interpretation of a high level task and definition of topological navigation subgoals; translation of topological navigation subgoals into geometrical path; calculation of the real path to execute; execution of this path, given the velocity commands and assuming a security function.
A comparison of selection time from walking and pull-down menus
Authors: Neff Walker, John B. Smelcer
Venue: Proceedings of the SIGCHI conference on Human factors in computing systems: Empowering people (1990)

This paper reports on an experiment that investigated factors which effect selection time from walking menus and bar or pull-down menus. The primary focus was on the use of impenetrable borders and on expanding target areas on the two menus types. The results show that both factors can be used to facilitate menu selection, with the use of borders being most beneficial. In addition, the results suggest that even on large monitors, the time required to access items from a bar menu is less than that required for the best walking menu.
Efficient macro-code emulation in hardwired pipelined processors
Authors: J. M. Mulder, R. J. Portier, A. Srivastava, R. in't Velt
Venue: Proceedings of the 21st annual workshop on Microprogramming and microarchitecture (1988)

Traditionally microcoded computers have been the ideal machines for implementing scalable architectures. These machines easily implement application-specific functionality in microcode and they allow architecturally transparent variation of cost/performance by trading off application code, microcode, and hardware. In contrast, hardwired machines are intrinsically incapable of implementing scalability, because they only implement a single level of interpretation. Recent RISC designs have introduced architectural features which partly resolve the scalability issues. They implement architectural openendness to allow application-specific functionality to be added to the architecture (by means of coprocessors and special function units). Additionally they define functions which, depending on application, cost, and performance, can be implemented in hardware or, by means of emulation, in software. Although identical from an abstract point of view, scalability by means of microprogramming and by means of emulation on a hardwired machine is significantly different. This paper describes the emulation facility provided in SCARCE (SCalable ARChitecture Experiment), a streamlined architecture specifically designed for a wide range of embedded applications, requiring high performance. While architecturally transparent, this emulation facility operates with little overhead (8 cycles), adds three control registers, and is always interruptible. By increasing the hardware investment, the overhead could be decreased to 4 cycles per trap.
An efficient algorithm for link-distance problems
Authors: Y. Ke
Venue: Proceedings of the fifth annual symposium on Computational geometry (1989)

The link distance between two points inside a simple polygon P is defined to be the minimum number of edges required to form a polygonal path inside P that connects the points. A link furthest neighbor of a point p &Egr; P is a point of P whose link distance is the maximum from p. The link center of P is the collection of points whose link distances to their link furthest neighbors are minimized. We present an &Ogr;(n log n) time and &Ogr;(n) space algorithm for computing the link center of a simple polygon P, where n is the number of vertices of P. This improves the previous &Ogr;(n2) time and space algorithm. Our algorithm essentially sweeps a chord through the polygon and spends &Ogr;(log n) time at each step. We demonstrate that the output of the algorithm, a sequence of sets of chords, is a powerful tool for solving several other link distance problems.
Efficient temporal reasoning (extended abstract)
Authors: E. A. Emerson, T. Sadler, J. Srinivasan
Venue: Proceedings of the 16th ACM SIGPLAN-SIGACT symposium on Principles of programming languages (1989)

There has been much interest in decision procedures for testing satisfiability (or validity) of formulae in various systems of Temporal Logic. This is due to the potential applications of such decision procedures to mechanical reasoning about correctness of concurrent programs. We show that there exist Temporal Logics that are (i) decidable in polynomial time, and (ii) still useful in applications. One surprising corollary of our results is that the fragment of CTL (Computation Tree Logic) actually used by Emerson Clarke [EC82] to synthesize concurrent programs from temporal specifications is decidable in polynomial time. Another is that the verification of many correctness properties of concurrent programs (such as in Owicki Lamport [OL82]) can be efficiently automated. This demonstrates that many useful correctness properties can be expressed with a rather restricted syntax. Finally, our results provide insight into the relation between the structural (i.e., syntactic) complexity of temporal logics and the complexity of their decision problems.
Distributed Assignment Algorithms for Multihop Packet Radio Networks
Authors: I. Cidon, M. Sidi
Venue: IEEE Transactions on Computers (1989)

New distributed dynamic channel assignment algorithms for a multihop packet radio network are introduced. The algorithms ensure conflict-free transmissions by the nodes of the network. The basic idea of the algorithms is to split the shared channel into a control segment and a transmission segment. The control segment is used to avoid conflicts among nodes and to increase the utilization of the transmission segment. It is shown how these algorithms can be used in order to determine time-division multiple access (TDMA) cycles with spatial reuse of the channel.
Modular synchronization in multiversion databases: version control and concurrency control
Authors: D. Agrawal, S. Sengupta
Venue: ACM SIGMOD Record (1989)

In this paper we propose a version control mechanism that enhances the modularity and extensibility of multiversion concurrency control algorithms. We decouple the multiversion algorithms into two components: version control and concurrency control. This permits modular development of multiversion protocols, and simplifies the task of proving the correctness of these protocols. An interesting feature of our framework is that the execution of read-only transactions becomes completely independent of the underlying concurrency control implementation. Also, algorithms with the version control mechanism have several advantages over most other multiversion algorithms.
User-centeredness, situatedness, and designing the media of computer documentation
Authors: Bob Johnson
Venue: ACM SIGDOC Asterisk Journal of Computer Documentation (1990)

User-centeredness has become a concept of much interest in a number of fields. Systems engineering, architecture, usability research and computer documentation, to name a few, are all areas of study which have, to one degree or another, adopted the terminology of user-centered philosophy in order to come to grips with the problem of how to design for users' needs. While there is much positive to be said about applying user-centered concepts to any discipline that wishes to pursue it, there is also a danger that the concept and philosophy of user-centered design could become, at best, empty rhetoric, and, at worst, fuel for lip service that could serve to undermine the humanitarian goals of a user-centered ethic. One concept which has already suffered a similar fate is that of &ldquo;problem-solving.&rdquo; Problem-solving has become, essentially, a hollow term when used by certain disciplines or institutions. For example, it is commonplace to hear representatives of business and industry refer to the need for 'good problem-solvers' in the world of business. One answer to this call has been the adoption of the terminology of problem-solving by the business curricula of many college and university business schools. At least one critic of current business school curricula has mentioned that theories of problem-solving have been diluted by the time they reach students (1). My own experience in teaching business writing at two universities has shown similar characteristics. Many of the business majors want to refer to themselves as &ldquo;good problem-solvers&rdquo; in their job application letters, but when asked to elaborate on or give an example of this, they often have simplified or inaccurate ideas of what should constitute an understanding of rich and powerful strategies. Certainly, the research and theory-building of Simon and Newell (2), or G. Polya (3) is applicable to the academic and workplace settings of business, but somehow the terminology of the theory lost its relevance during the translation. My purpose in this article is to discuss how user-centered computer documentation can avoid a similar fate. At present I fear our direction is veering in the direction of such a fate, and that one step toward correcting our course is to develop a clear theoretical understanding of what user-centeredness means to documentation. This means that although there may be a tacit theory which underlies current applications, it is important to make the theory visible, and thereby illuminate the gaps that may exist. In addition, my focus will also be upon the contribution that user-centered theory can bring to our understanding of how to design for the different media of computer documentation. As we all know, online and hypermedia documentation is becoming a central charge of our profession, and user-centered theory can go a long way in helping us understand the similarities and differences among the different media.