Showing papers by "Harold Abelson published in 1999"

Botanical computing: a developmental approach to generating interconnect topologies on an amorphous computer

Abstract: An amorphous computing medium is a system of irregularly placed asynchronous locally interacting computing elements I have demonstrated that amorphous media can b e con gured by a program common to all computing elements to generate highly complex prespeci ed patterns For example I can specify that an amorphous medium manifest a pattern representing the interconnection structure of an arbitrary electrical circuit My strategy is inspired by a botanical metaphor based on growing points and tropisms To make this strategy explicit I have developed the Growing Point Language GPL A growing point is a locus of activity in an amorphous medium A growing point propagates through the medium by transferring its activity from one computing element to a neighb o r As a growing point passes through the medium it e ects the di erentiation of the behaviors of the computing elements it visits The trajectory of the growing p o i n t is controlled by signals that are automatically carried through the medium from other di erentiated elements Such a response is called a tropism In this way a GPL program can exploit locality t o m a k e crude geometric inferences There is a wide variety of patterns that are expressible in GPL Examples include Euclidean constructions branching structures and simple text I prove that amorphous media can b e programmed to draw any prespeci ed planar graph and I obtain upper bounds on the amount of storage required by the individual processors to realize such a graph I also analyze how the e ectiveness of GPL programs depends upon the distribution of the computing elements Thesis Supervisor Gerald J Sussman Title Matsushita Professor of Electrical Engineering MIT Thesis Supervisor Harold Abelson Title Class of Professor of Computer Science and Engineering MIT Thesis Reader Thomas F Knight Title Senior Research Scientist Arti cial Intelligence Laboratory M I T