Automatic acquisition and use of some of the knowledge in physics texts

This report describes an investigation of the workings of expository technical texts with the goal of being able to automatically acquire and use some of the knowledge that they contain. The motivating question is: How does the presentation of material in college-level physics textbooks make it possible to solve problems based on that material? My hypothesis is that a lot of what is needed to solve problems is encoded fairly straightforwardly in the linguistic structure of the presentation text. Presentation passages often begin by describing a scene or telling a simple story. The physics is then introduced as a commentary on the described scene or story, perhaps by deriving an equation relating quantities in the story, or by introducing a physical phenomenon that occurs in the situations described. Problems are also presented as simple stories, and solving a problem requires locating in the presentation text a description of a situation that subsumes the one in the problem so that the associated equations can be applied. A program, called "Sagredo," was written to illustrate these ideas. Sagredo can read a passage of text describing elementary kinematics and can solve problems based on that material. As the program processes the source text, it interprets a set of definitions and rules in a unification-grammar based logic programming formalism, and constructs a representation of the occurrences described by the text. When it encounters passages that present new material, the program records definitions and rules that it can later instantiate when it reads and solves problems. One result of my reading lots of physics books was the realization that textbooks do much more than just list the laws of physics or show how to solve problems. Especially in the earlier chapters, where the fundamental principles and methods are treated, physics textbooks often resort more to rhetorical persuasion than to the sort of logical presentation that a program can easily follow. A complete account of the workings of expository technical texts must attend to wider roles that such texts play in the creation and maintenance of their communities of practice. Thesis Supervisor: Gerald Jay Sussman Title: Matsushita Professor of Electrical Engineering