In Section 3 we will see examples of this type of information.

We describe the development and (partial) Implementation of an "automated consultant" to advise non-expert engineers In the use of a general-purpose structural analysis program. The analysis program numerically simulates the behavior of a physical structure subjected to various mechanical loading conditions. The automated consultant, called SACON (Structural Analysis CONsultant), Is based on a version of the MYCIN program [Shortliffe74], originally developed to advise physicians In the diagnosis and treatment of infectious diseases. The domain-specific knowledge in MYCIN Is represented as situation-action rules, and is kept independent of the "inference engine" that uses the rules. By substituting structural engineering knowledge for the medical knowledge, the program was converted easily from the domain of Infectious diseases to the domain of structural analysis.

CONGEN: the constrained generation of chemical structures.

PUFF is now in routine use in Presbyterian Hospital, Pacific Medical Center (PMC), in San Francisco. The program produces a report, intended for patient records, that explains the clinical significance of measured quantitative test results and gives a diagnosis of the presence and severity of pulmonary disease in terms of the measured data, referral diagnosis, and patient history. "Rules", or statements of the form "IF condition THEN conclusion ", are used by the physiologist and the computer system to specify the system operation. The sequence of rules used to interpret the case also specifies a line of reasoning about the case, or the detailed explanation of the interpretation of the case. The use of rules for this type of knowledge based system is taken from the results of applied Artificial Intelligence research. In a 144 case prospective evaluation, there was a 91% overall rate of agreement between the rule based system diagnoses and the diagnoses of the designing physiologist; there was a 89% rate of agreement between the system diagnoses and diagnoses of a second independent physiologist.

References 67 October 27, 1977 1 Introduction This application addresses the continuation of research on the applications of artificial intelligence (Al) (1) to experimental molecular genetics. It is an extension of a longstanding effort to cultivate attention to ongoing laboratory research as a domain of explorations in artificial intelligence. Our major effort in this field had been in the DENDRNL project, with analytical organic chemistry as the object discipline.

The performance of a computer-based clinical consultation system is evaluated. The program, called MYCIN, is designed to function as an aid for infectious disease diagnosis are therapy selection, with an initial emphasis on bacteremias. The evaluation methodology is discussed, as well as the difficulties encountered in attempting to evaluate clinical judgments. Specialists in infectious diseases judged MYCIN's final therapy recommendation, and intermediate conclusions about the significance of the infection and identity of infecting organisms. The evaluation techniques described may be useful in assessing the performance of other clinical decision aids. Results of the evaluation show that the program's therapy recommendations meet Stanford experts' standards of acceptable practice 90.9% of the time (Table II), with some variation noted both among individual experts and between Stanford experts and others (Tables I and II).

The purpose of tnis paper is to describe a recent effort to generate, classify, and enulerate the sttreoisomers of all organic chemical structures consistent with a given empirical formula. The resulting theory is then converted into an algorithm which is programmed for a computer. The resulting program is used as an aid for computer assisted structure elucidation [1]. The proper group theoretical formulation is the key to the solution of the problem and will be discussed here. Simply st,'..ed, the problem is to generate, classify, and enumerate the possible stereoisomers for an organic chemical structure of defined constitution.

A typical problem in dynamic stereochemistry is to determine the mechanism of the rearrangement of a chemical structure such as 1. (I 352) Many of the problems already studied have involved degenerate rearrangements (those which interconvert chemical structures of the same geometry apart from any difference in the ligands) and only these will be considered here. Two groups and the mapping (homomorphism) between them are crucial to the proper description of problems of this kind. The first of these is the symmetry group of the chemical structure's skeleton (i.e, without ligands) and is designated P. This may be a point group, the rotation subgroup of a point group, or a nonrigid symmetry group [1]. Generally, this group can be represented as a permutation group on the ligands or on the skeletal sites however, in the most general case, this group is best represented as a permutation-inversion group [1].

In collaboration with other members of the MOLGEN project, the author developed a representation system called the "Unit Package" which became operational in July 1977. In some cases (and usually in ignorance), this work has duplicated other representation work that was happening at about the same time. The Unit Package is now being used by several other projects including two away from Stanford. It is written in INTERLISP and runs under the TENEX and TOPS20 operating systems. It is an interactive system for building knowledge-based programs. It also provides a substantial virtual memory so that knowledge bases of several thousand nodes can created without sacrificing the IlTrERLISP environment.

Counterexamples are provided disproving two independent claims that a simple but accurate method had been found to compute classes of symmetrically equivalent atoms in a molecule. Both methods are good approximations, but are nontheless ad hoc techniques which can sometimes fail to discriminate between atoms which arc, in fact, symmetrically distinct. A recem issue of this journal carried two papers23 dealing loop, at each stage of which a new score is computed for each directly or indirectly with "inexpensive" (in the sense of low atom based upon some function of the current score of that computational effort) methods of perceiving molecular atom arid the current scores of its immediate neighbors. More precisely, each article gives a set of rules term "score" here is used rather loosely; in the case of for scoring2 or comparing3 atoms in a molecule with the claim Morgan's algorithm it is an integer while in that of Shelley that if the scores are equal, or if the comparison shows no and Munk's it is a five-element vector. The important point difference, then the atoms arc symmetrically equivalent (i.e., is that a score is an entity which is associated with an atom can be interchanged by some symmetr) operation on the and which can be compared with the scores of other atoms molecule). Though both methods are doubtless very good in such a way that a strict "greater-less-equal" relationship approximations in the sense that they almost always yield the can be defined.