http://hdl.handle.net/1721.1/5459 http://hdl.handle.net/1721.1/46712 Dependency-Directed Backtracking in Non-Deterministic Scheme Zabih, Ramin Non-deterministic LISP can be used to describe a search problem without specifying the method used to solve the problem. We show that SCHEMER, a non-deterministic dialect of SCHEME, can support dependency-directed backtracking as well as chronological backtracking. Full code for a working SCHEMER interpreter that provides dependency-directed backtracking is included. This is a greatly revised version of a thesis submitted to the Massachusetts Institute of Technology Department of Electrical Engineering and Computer Science on January 2, 1987, in partial fulfillment of the requirements for the degree of Master of Science. http://hdl.handle.net/1721.1/45554 The Measurement of Visual Motion Hildreth, Ellen C. Ullman, Shimon The analysis of visual motion divides naturally into two stages: the first is the measurement of motion, for example, the assignment of direction and magnitude of velocity to elements in the image, on the basis of the changing intensity pattern; the second is the use of motion measurements, for example, to separate the scene into distinct objects, and infer their three-dimensional structure. In this paper, we present a computational study of the measurement of motion. Similar to other visual processes, the motion of elements is not determined uniquely by information in the changing image; additional constraint is required to compute a unique velocity field. Given this global ambiguity of motion, local measurements from the changing image, such as those provided by directionally-selective simple cells in primate visual cortex, cannot possibly specify a unique local velocity vector, and in fact, specify only one component of velocity. Computation of the full two-dimensional velocity field requires the integration of local motion measurements, either over an area, or along contours in the image. We will examine possible algorithms for computing motion, based on a range of additional constraints. Finally, we will present implications for the biological computation of motion. http://hdl.handle.net/1721.1/41999 Mini-Robot Group User's Guide Part 1: The 11/45 System Billmers, Meyer A. This USER'S GUIDE is in two parts. Part 1 describes the facilities of the mini-robot group 11/45 and the software available to persons using those facilities. It is intended for those writing their own programs to be run on the 11/45 system. A.I. Laboratory Working Papers are produced for internal circulation, and may contain information that is, for example, too preliminary or too detailed for formal publication. Although some will be given a limited external distribution, it is not intended that they should be considered papers to which reference can be made in the literature. This report describes research done at the Artificial Intelligence Laboratory of the Massachusetts Institute of Technology. Support for the laboratory's artificial intelligence research is provided in part by the Advanced Research Projects Agency of the Department of Defense under Office of Naval Research contract N00014-75-C-0643. http://hdl.handle.net/1721.1/41998 Using Message Passing Instead of the GOTO Construct Hewitt, Carl This paper advocates a programming methodology using message passing. Efficient programs are derived for fast exponentiation, merging ordered sequences, and path existence determination in a directed graph. The problems have been proposed by John Reynolds as interesting ones to investigate because they illustrate significant issues in programming. The methodology advocated here is directed toward the production of programs that are intended to execute efficiently in a computing environment with many processors. The absence of the GOTO construct does not seem to be constricting in any respect in the development of efficient programs using the programming methodology advocated here. This report describes research conducted at the Artificial Intelligence Laboratory of the Massachusetts Institute of Technology. Support for this research was provided in part by the Office of Naval Research of the Department of Defense under Contract N00014-75-C-0522.