Technical Reports
- Title:
- A Dynamic, Cut-Through Communications Protocol with Multicast.
- Author:
- Byrd, G. T., Nakano, R., and Delagi, B. A.
- Description:
- This paper describes a protocol to support point-to-point vinterprocessor communications with multicast. Dynamic, cut-through routing with local flow control is used to provide a high-throughput, low-latency communications path between processors. In addition, multicast transmissions are available, in which copies of a packet are sent to multiple destinations using common resources as much as possible. special packet terminators and selective buffering are introduced to avoid deadlock during multicasts. A simulated implementation of the protocol is also described.
- Topic:
- Computer science
- Subject:
- Stanford University. Computer Science Department
- Language:
- English
- Physical Description:
- 1 text file
- Publication Info:
- cau and Stanford (Calif.)
- Place created:
- Stanford (Calif.)
- Imprint:
- Stanford (Calif.)
- Genre:
- technical reports
- Identifier:
- CS-TR-1987-1178
- Collection:
- Stanford University, Department of Computer Science, Technical Reports
- Title:
- A Heuristic Refinement for Spacial Constraint Satisfaction Problems.
- Author:
- Brinkley, J., Buchanan, B., Altman, R., Duncan, B., and Cornelius, C.
- Description:
- The problem of arranging a set of physical objects according to a set of constraints is formulated as a geometric constraint satisfaction problem (GCSP), in which the variables are the objects, the possible locations of the objects are the possible values for the variables, and the constraints are geometric constraints between objects. A GCSP is a type of multidimensional constraint satisfaction problem in which the number of objects and/or the number of possible locations per object is too large to permit direct solution by backtrack search. A method is described for reducing these numbers by refinement along two dimensions. The number of objects is reduced by refinement of the structure, representing a group of objects as a single abstract object before considering each object individually. The abstraction used depends on domain specific knowledge. The number of locations per object is reduced by applying node and arc consistency algorithms to refine the accessible volume of each object. Heuristics are employed to control the order of operations (and hence to affect the efficiency of search) but not to change the correctness in the sense that no solutions that would be found by backtrack search are eliminated. Application of the method to the problem of protein structure determination is described.
- Topic:
- Computer science
- Subject:
- Stanford University. Computer Science Department
- Language:
- English
- Physical Description:
- 1 text file
- Publication Info:
- cau and Stanford (Calif.)
- Place created:
- Stanford (Calif.)
- Imprint:
- Stanford (Calif.)
- Genre:
- technical reports
- Identifier:
- CS-TR-1987-1142
- Collection:
- Stanford University, Department of Computer Science, Technical Reports
- Title:
- A Hierarchy of Temporal Properties.
- Author:
- Manna, Z ohar and Pnueli, Amir
- Description:
- We propose a classification of temporal properties into a hierarchy which refines the known safety-liveness classification of properties. The new classification recognizes the classes of safety, guarantee, persistence, fairness, and hyper-fairness. The classification suggested here is based on the different ways a property of finite computations can be extended into a property of infinite computations. For properties that are expressible by temporal logic and predicate automata, we provide a syntactic characterization of the formulae and automata that specify properties in the different classes. We consider the verification of properties over a given program, and provide a unique proof principle for each class.
- Topic:
- Computer science
- Subject:
- Stanford University. Computer Science Department
- Language:
- English
- Physical Description:
- 1 text file
- Publication Info:
- cau and Stanford (Calif.)
- Place created:
- Stanford (Calif.)
- Imprint:
- Stanford (Calif.)
- Genre:
- technical reports
- Identifier:
- CS-TR-1987-1186
- Collection:
- Stanford University, Department of Computer Science, Technical Reports
- Title:
- A Layered Environment for Reasoning about Action.
- Author:
- Hayes-Roth, B., Garvey, A., Johnson, M. V., and Hewett, M.
- Description:
- An intelligent systems reasons about -- controls, explains, learns about -- its action, thereby improving its efforts to achieve goals and function in its environment. In order to perform effectively, a system must have knowledge of the actions it can perform, the events and states that occur, and the relationships among instances of those actions, events and states. We represent such knowledge in a hiearchy of knowledge abstractions and impose uniform standards of knowledge content and representation on modules within each hierarchical level. We refer to the evolving set of such modules as the BB* environment. To illustrate, we describe selected elements of BB*: * the foundational BB1 architecture * the ACCORD framework for solving arrangement problems by means of an assembly method * two applications of BB1-ACCORD, the PROTEAN system for modeling protein structures and the SIGHTPLAN system for designing construction-site layouts * two hypothetical multifaceted systems that integrate ACCORD, PROTEAN and SIGHTPLAN with other possible BB* frameworks and applications.
- Topic:
- Computer science
- Subject:
- Stanford University. Computer Science Department
- Language:
- English
- Physical Description:
- 1 text file
- Publication Info:
- cau and Stanford (Calif.)
- Place created:
- Stanford (Calif.)
- Imprint:
- Stanford (Calif.)
- Genre:
- technical reports
- Identifier:
- CS-TR-1987-1147
- Collection:
- Stanford University, Department of Computer Science, Technical Reports
- Title:
- A Lower Bound for Radio Broadcast.
- Author:
- Bar-Noy, A., Linial, N., and Peleg, D.
- Description:
- A radio network is a synchronous network of processors that communicate by transmitting messages to their neighbors, where a processor receives a message in a given step if and only if it is silent in this step and precisely one of its neighbors transmits. In this paper we prove the existence of a family of radius-2 networks on n vertices for which any broadcast schedule requires at least Omega((log n/ log log n)2) rounds of transmissions. This almost matches an upper bound of O(log2 n) rounds for networks of radius 2 proved earlier by Bar-Yehuda, Goldreich, and Itai.
- Topic:
- Computer science
- Subject:
- Stanford University. Computer Science Department
- Language:
- English
- Physical Description:
- 1 text file
- Publication Info:
- cau and Stanford (Calif.)
- Place created:
- Stanford (Calif.)
- Imprint:
- Stanford (Calif.)
- Genre:
- technical reports
- Identifier:
- CS-TR-1988-1195
- Collection:
- Stanford University, Department of Computer Science, Technical Reports
- Title:
- A NETWORK-CENTRIC DESIGN FOR RELATIONSHIP-BASED RIGHTS MANAGEMENT.
- Collection:
- Stanford University, Department of Computer Science, Technical Reports
- Title:
- A Point-to-Point Multicast Communications Protocol.
- Author:
- Byrd, Gregory, Nakano, Russell, and Delagi, Bruce
- Description:
- Many network topologies have been proposed for connecting a large number of processor-memory pairs in a high-performance multiprocessor system. In terms of performance, however, the communications protocol decisions may be as crucial as topology. This paper describes a protocol to support point-to-point interprocessor communications with multicast. Dynamic, cut- through routing with local flow control is used to provide a high-throughput, low latency communications path between processors. In addition, multicast transmissions are available, in which copies of a packet are sent to multiple destinations using common resources as much as possible. Special packet terminators and selective buffering are introduced to avoid deadlock during multicasts. A simulated implementation of the protocol is also described.
- Topic:
- Computer science
- Subject:
- Stanford University. Computer Science Department
- Language:
- English
- Physical Description:
- 1 text file
- Publication Info:
- cau and Stanford (Calif.)
- Place created:
- Stanford (Calif.)
- Imprint:
- Stanford (Calif.)
- Genre:
- technical reports
- Identifier:
- CS-TR-1987-1146
- Collection:
- Stanford University, Department of Computer Science, Technical Reports
- Title:
- A Programming and Problem-Solving Seminar.
- Author:
- Rokicki, T. G. and Knuth, D. E.
- Description:
- This report contains edited transcripts of the discussions held in Stanford's course CS304, Problem Seminar, during winter quarter 1987. Since the topics span a large range of ideas in computer science, and since most of the important research paradigms and programming paradigms were touched on during the discussions, these notes may be of interest to graduate students of computer science at other universities, as well to their professors and to professional people in the "real world." The present report is the seventh in a series of such transcripts, continuing the tradition established in STAN- CS-77-606 (Michael J. Clancy, 1977), STAN-CS-79-707 (Chris Van Wyk, 1979), STAN-CS-81-863 (Allan A. Miller, 1981), STAN-CS-83-989 (Joseph S. Weening, 1983), STAN-CS-83-990 (John D. Hobby, 1983), and STAN-CS-85-1055 (Ramsey W. Haddad, 1985).
- Topic:
- Computer science
- Subject:
- Stanford University. Computer Science Department
- Language:
- English
- Physical Description:
- 1 text file
- Publication Info:
- cau and Stanford (Calif.)
- Place created:
- Stanford (Calif.)
- Imprint:
- Stanford (Calif.)
- Genre:
- technical reports
- Identifier:
- CS-TR-1987-1154
- Collection:
- Stanford University, Department of Computer Science, Technical Reports
- Title:
- An Experiment in Knowledge-based Signal Understanding Using Parallel Architectures.
- Author:
- Brown, Harold, Schoen, Eric, and Delagi, Bruce
- Description:
- This report documents an experiment investigating the potential of a parallel computing architecture to enhance the performance of a knowledge-based signal understanding system. The experiment consisted of implementing and evaluating an application encoded in a parallel programming extension of Lisp and executing on a simulated multiprocessor system. The chosen application for the experiment was a knowledge-based system for interpreting pre-processed, passively acquired radar emissions from aircraft. The application was implemented in an experimental concurrent, asynchronous object-oriented framework. This framework, in turn, relied on the services provided by the underlying hardware system. The hardware system for the experiment was a simulation of various sized grids of processors with inter-processor communication via message-passing. The experiment investigated the effects of various high-level control strategies on the quality of the problem solution, the speedup of the overall system performance as a function of the number of processors in the grid, and some of the issues in implementing and debugging a knowledge-based system on a message-passing multiprocessor system. In this report we describe the software and (simulated) hardware components of the experiment and present the qualitative and quantitative experimental results.
- Topic:
- Computer science
- Subject:
- Stanford University. Computer Science Department
- Language:
- English
- Physical Description:
- 1 text file
- Publication Info:
- cau and Stanford (Calif.)
- Place created:
- Stanford (Calif.)
- Imprint:
- Stanford (Calif.)
- Genre:
- technical reports
- Identifier:
- CS-TR-1986-1134
- Collection:
- Stanford University, Department of Computer Science, Technical Reports
- Title:
- An Instrumented Architectural Simulation System.
- Author:
- Delagi, B., Saraiya, N., Nishimura, S., and Byrd, G.
- Description:
- Simulation of systems at an architectural level can offer an effective way to study critical design choices if 1. the performance of the simulator is adequate to examine designs executing significant code bodies -- not just toy problems or small application fragments 2. the details of the simulation include the critical details of the design 3. The view of the design presented by the simulator instrumentation leads to useful insights on the problems with the design 4. there is enough flexibility in the simulation system so that the asking of unplanned questions is not suppressed by the weight of the mechanics involved in making changes either in the design or its measurement. A simulation system with these goals is described together with the approach to its implementation. Its application to the study of a particular class of multiprocessor hardware system architectures is illustrated.
- Topic:
- Computer science
- Subject:
- Stanford University. Computer Science Department
- Language:
- English
- Physical Description:
- 1 text file
- Publication Info:
- cau and Stanford (Calif.)
- Place created:
- Stanford (Calif.)
- Imprint:
- Stanford (Calif.)
- Genre:
- technical reports
- Identifier:
- CS-TR-1987-1148
- Collection:
- Stanford University, Department of Computer Science, Technical Reports
- Title:
- An Introduction to the DDL-P Language: Technical Report No. 163.
- Collection:
- Stanford University, Department of Computer Science, Technical Reports
- Title:
- Beta Operations: Efficient Implementation of a Primitive Parallel Operation.
- Author:
- Cohn, Evan R. and Haddad, Ramsey W.
- Description:
- We will consider the primitive parallel operation of the Connection Machine, the Beta Operation. Let the imput size of the problem be N and output size M. We will show how to perforrn the Beta Operation on an N-node hypercube in O(log N + $log^2$ M) time. For a $\sqrt{N} x \sqrt{M}$ mesh-of-trees, we require O(log N + $\sqrt{M}$) time.
- Topic:
- Computer science
- Subject:
- Stanford University. Computer Science Department
- Language:
- English
- Physical Description:
- 1 text file
- Publication Info:
- cau and Stanford (Calif.)
- Place created:
- Stanford (Calif.)
- Imprint:
- Stanford (Calif.)
- Genre:
- technical reports
- Identifier:
- CS-TR-1986-1129
- Collection:
- Stanford University, Department of Computer Science, Technical Reports
- Title:
- Bibliography; Department of Computer Science Technical Reports, 1963-1988.
- Author:
- Na, Taleen M.
- Description:
- This report lists, in chronological order, all reports published by the Stanford Computer Science Department (CSD) since 1963. Each report is identified by CSD number, author's name, title, number of pages, and date. If a given report is available from the department at the time of the Bibliography's printing, price is listed. For convenience, an author index, ordering information, codes, and alternative sources are also included.
- Topic:
- Computer science
- Subject:
- Stanford University. Computer Science Department
- Language:
- English
- Physical Description:
- 1 text file
- Publication Info:
- cau and Stanford (Calif.)
- Place created:
- Stanford (Calif.)
- Imprint:
- Stanford (Calif.)
- Genre:
- technical reports
- Identifier:
- CS-TR-1987-1180
- Collection:
- Stanford University, Department of Computer Science, Technical Reports
- Title:
- Blazenet: A Photonic Implementable Wide-Area Network.
- Author:
- Haas, Z . and Cheriton, D. R.
- Description:
- High-performance wide-area networks are required to interconnect clusters of computers connected by local area and metropolitan area networks. Optical fiber technology provides long distance channels in the multi-gigabit per second range. The challenge is to provide switching nodes that handle these data rates with minimum delay, and at a reasonable cost. In this paper, we describe a packet switching network, christened Blazenet, that provides low delay and has minimal memory requirements. It can be extended to support multicast and priority delivery. Such a network can revolutionize the opportunities for distributed command and control, information and resources sharing, real-time conferencing, and wide-area parallel computation, to mention but a few applications.
- Topic:
- Computer science
- Subject:
- Stanford University. Computer Science Department
- Language:
- English
- Physical Description:
- 1 text file
- Publication Info:
- cau and Stanford (Calif.)
- Place created:
- Stanford (Calif.)
- Imprint:
- Stanford (Calif.)
- Genre:
- technical reports
- Identifier:
- CS-TR-1987-1185
- Collection:
- Stanford University, Department of Computer Science, Technical Reports
- Title:
- CAREL: A Visible Distributed Lisp.
- Author:
- Davies, Byron
- Description:
- CAREL is a Lisp implementation designed to be a high-level interactive systems programming language for a distributed-memory multiprocessor. CAREL insulates the user from the machine language of the multiprocessor architecture, but still makes it possible for the user to specify explicitly the assignment of tasks to processors in the multiprocessor network. CAREL has been implemented to run on a TI Explorer Lisp machine using Stanford's CARE multiprocessor simulator. CAREL is more than a language: real-time graphical displays provided by the CARE simulator make CAREL a novel graphical programming environment for distributed computing. CAREL enables the user to create programs interactively and then watch them run on a network of simulated processors. As a CAREL program executes, the CARE simulator graphically displays the activity of the processors and the transmission of data through the network. Using this capability, CAREL has demonstrated its utility as an educational tool for multiprocessor computing.
- Topic:
- Computer science
- Subject:
- Stanford University. Computer Science Department
- Language:
- English
- Physical Description:
- 1 text file
- Publication Info:
- cau and Stanford (Calif.)
- Place created:
- Stanford (Calif.)
- Imprint:
- Stanford (Calif.)
- Genre:
- technical reports
- Identifier:
- CS-TR-1986-1126
- Collection:
- Stanford University, Department of Computer Science, Technical Reports
- Title:
- Considerations for Multiprocessor Typologies.
- Author:
- Byrd, Gregory and Delagi, Bruce
- Description:
- Choosing a multiprocessor interconnection topology may depend on high-level considerations, such as the intended application domain and the expected number of processors. It certainly depends on low-level implementation details, such as packaging and communications protocols. We first use rough measures of cost and performance to characterize several topologies. We then examine how implementation details can affect the realizable performance of a topology.
- Topic:
- Computer science
- Subject:
- Stanford University. Computer Science Department
- Language:
- English
- Physical Description:
- 1 text file
- Publication Info:
- cau and Stanford (Calif.)
- Place created:
- Stanford (Calif.)
- Imprint:
- Stanford (Calif.)
- Genre:
- technical reports
- Identifier:
- CS-TR-1987-1144
- Collection:
- Stanford University, Department of Computer Science, Technical Reports
- Title:
- Experiments in Automatic Theorem Proving.
- Author:
- Bellin, G. and Ketonen, J.
- Description:
- The experiments described in this report are proofs in EKL of properties of different LISP programs operating different representations of the same mathematical structures -- finite permutations. EKL is an interactive proof checker based upon the language of higher order logic, higher order unification and a decision procedure for a fragment of first order logic. The following questions are asked: What representations of mathematical structure and facts are better suited for formalization and also applicable to several interesting situations? What methods and strategies will make it possible to prove automatically an extensive body of mathematical knowledge? Can higher order logic be conveniently applied in the proof of elementary facts? The fact (*) that finite permutations form a group is proved from the axioms of arithmetic and elementary set theory, via the "Pigeon Hole Principle" (PHP). Permutations are represented (1) as association lists and (2) as lists of numbers. In representation (2) operations on permutations are represented (2.1) using predicates (2.2) using functions. Proofs of (*) using the different representations are compared. The results and conclusions include the following. Methods to control the rewriting process and to replace logic inference by high order rewriting are presented. PHP is formulated as a second order statement which is then easily applied to (1) and (2). This demonstrates the value of abstract, higher order formulation of facts for application in different contexts. A case is given in which representation of properties of programs by predicates may be more convenient than by functions. Evidence is given that convenient organization of proofs into lemmata is essential for large scale computer aided theorem proving.
- Topic:
- Computer science
- Subject:
- Stanford University. Computer Science Department
- Language:
- English
- Physical Description:
- 1 text file
- Publication Info:
- cau and Stanford (Calif.)
- Place created:
- Stanford (Calif.)
- Imprint:
- Stanford (Calif.)
- Genre:
- technical reports
- Identifier:
- CS-TR-1987-1155
- Collection:
- Stanford University, Department of Computer Science, Technical Reports
- Title:
- Experiments with a Knowledge-Based System on a Multiprocessor.
- Author:
- Nakano, Russell and Minami, Masafumi
- Description:
- This paper documents the results we obtained and the lessons we learned in the design, implementation, and execution of a simulated real-time application on a simulated parallel processor. Specifically, our parallel program ran 100 times faster on a 100-processor multiprocessor. The machine architecture is a distributed-memory multiprocessor. The target machine consists of 10 to 1000 processors, but because of simulator limitations, we ran simulations of machines consisting of 1 to 100 processors. Each processor is a computer with its own local memory, executing an independent instruction stream. There is no global shared memory; all processes communicate by message passing. The target programming environment, called Lamina, encourages a programming style that stresses performance gains through problem decomposition, allowing many processors to be brought to bear on a problem. THe key is to distribute the processing load over replicated objects, and to incresase throughput by building pipelined sequences of objects that handle stages of problem solving. We focused on a knowledge-based application that simulates real-time understanding of radar tracks, called Airtrac. This paper describes a portion of the Airtrac application implemented in Lamina and a set of experiments that we performed. We confirmed the following hypotheses: 1) Performance of our concurrent program improves with additional processors, and thereby attains a significant level of speedup. 2) Correctness of our concurrent program can be maintained despite a high degree of problem decomposition and highly overloaded input data conditions.
- Topic:
- Computer science
- Subject:
- Stanford University. Computer Science Department
- Language:
- English
- Physical Description:
- 1 text file
- Publication Info:
- cau and Stanford (Calif.)
- Place created:
- Stanford (Calif.)
- Imprint:
- Stanford (Calif.)
- Genre:
- technical reports
- Identifier:
- CS-TR-1987-1188
- Collection:
- Stanford University, Department of Computer Science, Technical Reports
- Title:
- Firmware Approach to Fast Lisp Interpreter.
- Author:
- Okuno, H., Osato, N., and Takeuchi, I.
- Description:
- The approach to speed up a Lisp interpreter by implementing it in firmware seems promising. A microcoded Lisp interpreter shows good performance for very simple benchmarks, while it often fails to provide good performance for larger benchmarks and applications unless speedup techniques are devised for it. This was the case for the TAO/ELIS system. This paper describes various techniques devised for the TAO/ELIS system in order to speed up the interpreter of the TAO language implemented on the ELIS Lisp machine. The techniques include data type dispatch, variable access, function call and so on. TAO is not only upward compatible with Common Lisp, but also incorporates logic programming, object-oriented programming and Fortran/C-like programming into Lisp programming. TAO also provides concurrent programming and supports multiple users (up to eight users). The TAO interpreter for those programming paradigms is coded fully in microcodes. In spite of rich functionalities, the speed of interpreted codes of TAO is comparable to that of compiled codes of commercial Lisp machines. Furthermore, the speeds of the interpreted codes of the same program written in various prograrnming paradigms in TAO does not differ so much. This speed balance is very important for the user. Another outstanding feature of the TAO/ELIS system is its firmware development environments. Micro Assembler and Linker are written in TAO, which enables the user to use the capability of TAO in microcodes. Since debugging tools are also written in mini-Lisp, many new tools were developed in parallel to debugging of microcodes. This high level approach to firmware development environments is very important to provide high productivity of development.
- Topic:
- Computer science
- Subject:
- Stanford University. Computer Science Department
- Language:
- English
- Physical Description:
- 1 text file
- Publication Info:
- cau and Stanford (Calif.)
- Place created:
- Stanford (Calif.)
- Imprint:
- Stanford (Calif.)
- Genre:
- technical reports
- Identifier:
- CS-TR-1987-1184
- Collection:
- Stanford University, Department of Computer Science, Technical Reports
- Title:
- Instrumented Architectural Simulation.
- Author:
- Delagi, Bruce A., Saraiya, Nakul, Nishimura, Sayuri, and Byrd, Greg
- Description:
- Simulation of systems at an architectural level can offer an effective way to study critical design choices if (1) the performance of the simulator is adequate to examine designs executing significant code bodies -- not just toy problems or small application fragments, (2) the details of the simulation include the critical details of the design, (3) the view of the design presented by the simulator instrumentation leads to useful insights on the problems with the design, and (4) there is enough flexibility in the simulation system so that the asking of unplanned questions is not suppressed by the weight of the mechanics involoved in making changes either in the design or its measurement. A simulation system with these goals is described together with the approach to its implementation. Its application to the study of a particular class of multiprocessor hardsware system architectures is illustrated.
- Topic:
- Computer science
- Subject:
- Stanford University. Computer Science Department
- Language:
- English
- Physical Description:
- 1 text file
- Publication Info:
- cau and Stanford (Calif.)
- Place created:
- Stanford (Calif.)
- Imprint:
- Stanford (Calif.)
- Genre:
- technical reports
- Identifier:
- CS-TR-1987-1189
- Collection:
- Stanford University, Department of Computer Science, Technical Reports
- Title:
- Intelligent Tutoring Systerns: A Tutorial Survey.
- Author:
- Clancey, William J.
- Description:
- This survey of Intelligent Tutoring Systems is based on a tutorial originally presented by John Seely Brown, Richard R. Burton (Xerox - PARC, USA) and William J. Clancey at the National Conference on AI (AAAI) in Austin, TX in August, 1984. The survey describes the components of tutoring systems, different teaching scenarios, and their relation to a theory of instruction. The underlying pedagogical approach is to make latent knowledge manifest, which the research accomplishes by different forms of qualitative modeling: simulating physical processes; simulating expert problem-solving, including strategies for montoring and controling problem solving (metacognition); modeling the plans behind procedural behavior; and forcing articulation of model inconsistencies through the Socratic method of instruction.
- Topic:
- Computer science
- Subject:
- Stanford University. Computer Science Department
- Language:
- English
- Physical Description:
- 1 text file
- Publication Info:
- cau and Stanford (Calif.)
- Place created:
- Stanford (Calif.)
- Imprint:
- Stanford (Calif.)
- Genre:
- technical reports
- Identifier:
- CS-TR-1987-1174
- Collection:
- Stanford University, Department of Computer Science, Technical Reports
- Title:
- Knowledge Base Refinement by Monitoring Abstract Control Knowledge.
- Author:
- Wilkins, D. C. and Buchanan, B. G.
- Description:
- An explicit representation of the problem solving method of an expert system shell as abstract control knowledge provides a powerful foundation for learning. This paper describes the abstract control knowledge of the Heracles expert system shell for heuristic classification problems, and describes how the Odysseus apprenticeship learning program uses this representation to automate "end-game" knowledge acquisition. Particular emphasis is given to showing how abstract control knowledge facilitates the use of underlying domain theories by a learning program.
- Topic:
- Computer science
- Subject:
- Stanford University. Computer Science Department
- Language:
- English
- Physical Description:
- 1 text file
- Publication Info:
- cau and Stanford (Calif.)
- Place created:
- Stanford (Calif.)
- Imprint:
- Stanford (Calif.)
- Genre:
- technical reports
- Identifier:
- CS-TR-1987-1182
- Collection:
- Stanford University, Department of Computer Science, Technical Reports
- Title:
- Local Shape from Specularity.
- Author:
- Healey, Glenn and Binford, Thomas O.
- Description:
- We show that highlights in images of objects with specularly reflecting surfaces provide significant information about the surfaces which generate them. A brief survey is given of specular reflectance models which have been used in computer vision and graphics. For our work, we adopt the Torrance-Sparrow specular model which, unlike most previous models, considers the underlying physics of specular reflection from rough surfaces. From this model we derive powerful relationships between the properties of a specular feature in an image and local properties of the corresponding surface. We show how this analysis can be used for both prediction and interpretation in a vision system. A shape from specularity system has been implemented to test our approach. The performance of the system is demonstrated by careful experiments with specularly reflecting objects.
- Topic:
- Computer science
- Subject:
- Stanford University. Computer Science Department
- Language:
- English
- Physical Description:
- 1 text file
- Publication Info:
- cau and Stanford (Calif.)
- Place created:
- Stanford (Calif.)
- Imprint:
- Stanford (Calif.)
- Genre:
- technical reports
- Identifier:
- CS-TR-1986-1137
- Collection:
- Stanford University, Department of Computer Science, Technical Reports
- Title:
- Log Files: An Extended File Service Exploiting Write-Once Storage.
- Author:
- Finlayson, R. S. and Cheriton, D. R.
- Description:
- A log service provides efficient storage and retrieval of data that is written sequentially (append-only) and not subsequently modified. Application programs an subsystems use log services for recovery, to record security audit trails, and for perforrnance monitoring. Ideally, a log service should accomodate very large, long-lived logs, and provlde efficient retrieval and low space overhead. In this paper, we describe the design and implementation of the Clio log service. Clio provides the abstraction of log files: readable, append-only files that are accessed in the same way as conventional files. The underlying storage medium is required only to be append-only; more general types of write access are not necessary. We show how log files can be implemented efficiently and robustly on top of such storage media - in particular, write-once. optical disk. In addition, we describe a general application software storage architecture that makes use of log files.
- Topic:
- Computer science
- Subject:
- Stanford University. Computer Science Department
- Language:
- English
- Physical Description:
- 1 text file
- Publication Info:
- cau and Stanford (Calif.)
- Place created:
- Stanford (Calif.)
- Imprint:
- Stanford (Calif.)
- Genre:
- technical reports
- Identifier:
- CS-TR-1987-1175
- Collection:
- Stanford University, Department of Computer Science, Technical Reports