Articles by Bruce Buchanan

Multi-arm robotic systems are more difficult to control than single-arm systems. An example is the coordination of two arms picking up a long beam from a conveyor and carrying it to another location. The kinematics of this task are discussed. A. Hemami, F. Ranjbaran, R.M.H. Cheng, "A case study of two-robot-arm workcell material handling," Journal of Robotic Systems, 8, 21-37, February 1991. (Concordia University, Montreal, Quebec) Computing for the next generation will involve writing and dr

Department of Computer Science University of Pittsburgh Pittsburg, PA The Hypertext model of structuring and presenting information leads to the question of how people, as readers, ordinarily classify texts. A new approach (repertory grid analysis) from Personal Construct Theory provides insights. The classes of criteria ("constructs") emerge, dealing with how text is read (such as once, or repeatedly), why it is read (for example, for professional or personal reasons), and what type of inf

Department of Computer Science University of Pittsburgh Pittsburgh, Pa. Mobile robots in the workplace must select collision-free paths in real time, in environments that are constantly changing. A new algorithm is proposed that is based on representing obstacles in a quadtree, from data, for example, from a ceiling camera. Experimental results show faster calculations of collision-free paths than conventional algorithms. H. Noborio, N. Tomohide, S. Arimoto, "A quadtree-based path-planning alg

COMPUTATIONAL SCIENCE BY BRUCE G. BUCHANAN Department of Computer Science University of Pittsburgh Pittsburgh, Pa. " Diagnosis in medicine has been a testbed for developing ideas about troubleshooting in .engineering disciplines. A recently published paper addresses a fundamental problem of defining the variety of knowledge structures—including causal models—needed to support a broad spectrum of reasoning mechanisms used in diagnosis. A systematic method of defining concepts and l

COMPUTATIONAL SCIENCE BY BRUCE G. BUCHANAN Department of Computer Science University of Pittsburgh Pittsburgh, Pa. " To segment image data means to separate important parts of the image from the background. Fingerprints are often low-contrast, smudged, and noisy images, and thus offer a good test of segmentation algorithms. A composite of two methods is proposed that gives better performance than either alone. B.M. Mehtre, B. Chatterjee, “Segmentation of fingerprint images—a compo

COMPUTATIONAL SCIENCE BY BRUCE G. BUCHANAN Department of Computer Science University of Pittsburgh Pittsburgh, Pa. " The Boyer-Moore string searching algorithm is a best choice for many problems in which a pattern of length m is to be matched in a text of length n, for small alphabets or long pattems. A recent paper exploits the-space-time trade-off to improve the algorithm’s speed by 50% for long patterns. Some experimental results -are presented that also indicate the effecfiveness of

COMPUTATIONAL SCIENCE BY BRUCE G. BUCHANAN Department of Computer Science University of Pittsburgh Pittsburgh, Pa. " In a recent review of a 10-year software project, a grandmaster of programming opens his log book of errors and changes. He classifies 15 reasons for making changes and analyzes outstanding examples of most of them. His conclusions about the ubiquity of errors should be taped beside every programmer’s terminal. Programming has always been a humbling experience; programmin

The Scientist has asked a group of experts to comment periodically upon recent articles that they have found noteworthy. Their selections, presented here in every issue, are neither endorsements of content nor the result of systematic searching. Rather, the list represents personal choices of articles the columnists believe the scientific community as a whole may also find interesting. Reprints of any articles cited here may be ordered through The Genuine Article, 3501 Market St., Philadelphia,

COMPUTATIONAL SCIENCE BY BRUCE G. BUCHANAN Department of Computer Science University of Pittsburgh Pittsburgh, Pa. " The Charlotte distributed operating system is a test bed for the development of techniques for exploiting large-grain parallelism. It runs on a collection of 20 VAX-I 11750 computers. A recent paper gives conclusions drawn from several years’ experience with the system. R.A. Finkel, M.L. Scott, Y. Artsy, H.-Y Chang, “Experience with Charlotte: Simplicity and functi

COMPUTATIONAL SCIENCES BY BRUCE G. BUCHANAN Department of Computer Science University of Pittsburgh Pittsburgh, Pa. " Scientists rely on information, and information management in this century now necessarily involves computers. Yet many scientists are frustrated in attempts to use computers for communicating with colleagues, analyzing data, and otherwise carrying out research. Are report, commissioned by the National Academy of Sciences, examines the use of information technologies (mostly c

COMPUTATIONAL SCIENCE BY BRUCE G. BUCHANAN Department of Computer Science University of Pittsburgh Pittsburgh, Pa. " When databases are distributed, the tradeoff between consistency of files and their availability is exacerbated. A new paper presents a variation of the voting algorithm that achieves greater availability than other algorithms and, moreover, that is proved to be correct. S. Jajodia, D. Mutchier, “A pessimistic consistency control a1gorithm for replicated tiles which achie

COMPUTATIONAL SCIENCE BY BRUCE G. BUCHANAN Department of Computer Science University of Pittsburgh Pittsburgh, Pa. " Electronic mail systems simplify communication but often result in information overload, or sometimes a flood of “junk mail.” Or the horizon are software tools that filter messages according tc criteria defined by the individual. This paper describes one such prototype. S. Pollock, “Arnie-based message filtering system,” acm Transactions on Office Infor

COMPUTATIONAL SCIENCES BY BRUCE G. BUCHANAN Department of Computer Science University of Pittsburgh Pittsburgh, Pa. " Expert systems require substantial knowledge bases, yet the process of acquiring the requisite knowledge can be cumbersome. Automating the learning of new knowledge has been the topic of considerable research. A new study brings together in one framework the various approaches to knowledge acquisition and uses it to evaluate their applicability to building expert systems. V.L

COMPUTATIONAL SCIENCES BY BRUCE G. BUCHANANBR> Department of Computer Science University of Pittsburgh Pittsburgh, Pa. " Are computer-based text editors more efficient for reading and writing than conventional paper documents? Many factors influence the answer, seven of which were reported in a recent study. Advanced workstations offer enough advantages over personal computers, partly because there is more flexibilty in the user interface. Neither is superior to paper for reading (or proofre

COMPUTATIONAL SCIENCES BY BRUCE G. BUCHANAN Department of Computer Science University of Pittsburgh Pittsburgh, Pa. "Group decision making has not benefited as much from computer-based tools as individuals have. A recent article suggests how groups can benefit more. K.L. Kraemer, J.L. King, “Computer-based systems for cooperative work and group decision making,” ACM Computing, Surveys, 20 (2), 115-46, June 1988. " When learning from examples, computer programs start with a bins&#