I. INTRODUCTION Describing scientific theory formation as an information-processing problem suggests breaking the problem into subproblems and searching solution spaces for plausible items in the theory. A computer program called meta-DEN D RAL embodies this approach to the theory formation problem within a specific area of science. Scientific theories are judged partly on how well they explain the observed data, how general their rules are, and how well they are able to predict new events. The meta-D END RA L program attempts to use these criteria, and more, as guides to formulating acceptable theories. The problem for the program is to discover conditional rules of the form S-421, where the S's are descriptions of situations and the A's are descriptions of actions. The rule is interpreted simply as'When the situation S occurs, action A occurs'. The theory formation program first generates plausible A's for theory sentences, then for each A it generates plausible S's. At the end it must integrate the candidate rules with each other and with existing theory. In this paper we are concerned only with the first two tasks: data interpretation (generating plausible A's) and rule formation (generating plausible S's for each A). This paper describes the space of actions (A's), the space of situations (S's) and the criteria of plausibility for both. This requires mentioning some details of the chemical task since the generators and the plausibility criteria gain their effectiveness from knowledge of the task. The theory formation task As in the past, we prefer to develop our ideas in the context of a specific task area.

B.RANDELL 3 PROGRAM PROOF AND MANIPULATION 2 Some techniques for proving correctness of programs which alter data structures.

A programming language based on sets; motivation and examples.

The program contains a rough theory of mass spectrometry which is still in its formative stages.

Experimentation serves three purposes: (a) hypothesis testing, (b) gathering of new data to constrain the theory generator, and (c) manipulation of the external system to reveal its structure. A theory formation system, EG, is described that employs experimentation and observation techniques to develop a theory of the UNIX file system and executive-level file commands. This theory formation task is more complex than previous efforts, and the goal of the project is to determine which existing theory formation methods are applicable and what new methods need to be developed. Previous techniques arc reviewed, and none of them arc found to be applicable. A new technique, based on controlled experimentation, is de3cribcd, and a hypothetical trace of EG's execution is presented. Key terms: 'Theory formation, generate-and-test, controlled experimentation, exploratory experiments, observation experiments, hypothesis-test experiments, credit assignment, new terms.

Because this paper is about computer programs thal generate explanations, my debt to Prof. Hempel will be obvious. However, insofar as I wish to use the term'discovery' to cover the activity of finding explanations, I know that Prof. Hempel will not entirely agree with these ideas about mechanizing the activity. The purpose of this paper is to elaborate a very simple idea: that discovery in science and medicine can be profitably viewed as systematic exclusion of hypotheses. That is, hypotheses that explain empirical data can be found systematically by methods that can be implemented in computer programs. The conditions under which this view makes sense are an important part of the elaboration. Two necessary conditions are that the space of relevant hypotheses is definable and that there exist criteria of rejection and acceptability. Because the space of hypotheses is immense for most interesting problems, it is also desirable that there exist criteria for guiding a systematic search.

A. Conduct of Science: Computers and Communications and opportunities for the scientific community to share The claim of science to universal validity is supportable only

The discussion centers on a specific video terminal designed and constructed by the authors. This terminal is based on the Intel 8080 microprocessor and is equipped with software sufficient to emiflate the characteristics of standard video terminals required by eral available screen -oriented text editors in common use at sites throughout the ARPAnet (such as E [Samuel, 1978] and TV-Edit [kanerva, 1975]). Screen-oriented editors2 differ from other editors In their use of high-speed video terminals to display the contents of large sections of a file being edited. As editing operations are performed, the display Is revised to indicate their effects on the file (i.e., editing operates In a What you see is what you get mode). Such editors require ter.linals capable of primitive text-processing operations, such as inserting a character in a line of text by shifting the existing characters. In addition to such capabilities, the terminal is typically expected to support 8-bit transmission (instead of the usual 7 bits plus parity), selectable modes for displaying characters (e.g., normal or inverse video, blinking, or dual intensity), and an 80-character line width.

In the early days of computing, these goals were central to the new discipline called cybernetics [126], [2]. Over the past two decades, progress toward these goals has come from a variety of fields - notably computer science, psychology, adaptive control theory, pattern recognition, and philosophy. Substantial progress has been made in developing techniques for machine learning in highly restricted environments.

Cohen, Design Considerations for a Program to Provide Consultations in Clinical Therapeutics, in Proceedings of San Diego Biomedical Symposium, February 1974.