Chemical Literature, Volume 27, Number 1, Spring 1975 Page: 10
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__10 _CHEMICAL LITERATURE SPRING 1975
29. AUGMENTED CONNECTIVITY MOLFORM--A
TECHNIQUE FOR RECOGNITION
OF STRUCTURE TOPOLOGY IDENTITY.
R.G. Freeland, S.J. Funk, L.J. O'Korn, G.A.
Wilson, Chemical Abstracts Service, The Ohio
State University, Columbus, OH 43210.
The CAS Chemical Registry System, which is
based on a concept suggested originally by G. Malcolm
Dyson, grew out of research in the early 1960's in which
Harry Morgan of the CAS staff, building upon work
supplied by Du Pont, perfected an algorithm for generating
a unique and unambiguous computer-language description
of a chemical structure. This algorithm became the foundation
of a computer-based system that uniquely identifies
chemical substances on the basis of structure.
Because of the importance of this algorithm to the
CAS Chemical Registry System, techniques have been
developed to improve validation of the algorithm and insure
integrity of the Chemical Registry data base.
These improved validation procedures are based on
a simple and highly efficient computer calculation of a
compact representation for a structure; this representation
is called the Augmented Connectivity Molform.
The derivation of the Augmented Connectivity
Molform, its use as a validation tool, results from its use,
and its other potential uses will be presented. These results
will be based on the use of the Augmented Connectivity
Molform on the CAS Chemical Registry data base of 2.8
million substances.
30. GRAPH THEORETICAL CONSTRAINTS ON
LINEARIZATION ALGORITHMS FOR CANONICAL
CHEMICAL NOMENCLATURE.
Alton F. Sanders, Computer Science Dept., State
University of New York, Stony Brook, NY 11794.
Although there is an obvious need for an efficient
algorithm to convert chemical graphs into canonical linear
representation, so far no one has been able to devise such an
algorithm. The difficulty may be due to an inherent
complexity of chemical graphs. Using techniques of graph
theory and the theory of computational complexity, it has
been possible to analyze the problems of conversion of a
structural representation of an arbitrary chemical graph
into WLN, a canonical connection table, and a proposed
variation of WLN called ALWIN. This paper will describe
some of the many subproblems which are contained in
these problems, giving computational bounds where possible.
The conversion into WLN will be shown to belong to a
group of problems known as NP-complete, suggesting that
any conversion algorithm must be inefficient for some
subset of chemical graphs. Moreover, there is evidence that
conversion of chemical graphs into any canonical linear
notation belongs to the set of NP-complete problems.
31. EFFICIENT SCREENS FOR THE WRAIR SYSTEM.
A PROGRESS REPORT. Alfred P.
Feldman and Louis Hodes, Walter Reed Army
Institute of Research, Washington, D.C. 20012,
National Cancer Institute, NIH, Bethesda, MD
20014.
An earlier paper (presented at the 168th ACS
meeting, Sept. 1974) described a process which, based on
heuristic and information theoretic principles, produced
efficient screens for chemical-compound retrieval. It was an
iterative procedure, which generated new screens by extending
fragments occurring with high file incidence. In
the present communication, the screens obtained are exam ined.
Using a sample (10%) file, about 3000 screens were
initially produced. Their number was reduced by eliminating
screens that were partly redundant, for example,
screens occurring with a frequency somewhat greater than
one half that of their predecessors. (A predecessor is a
previously obtained screen that is also a substructure of the
one at hand.) Although, by themselves, these redundant
screens have good discrimination, when used in conjunction
with their predecessors, the added retrieval capability
is marginal. By eliminating them, the number of screens
remaining was reduced by about one quarter.
Using the already described superimposed code for
assembling the screens for a compound, it was found that a
dedicated space of about 150 bits suffices to screen a file of
approximately 250,000 compounds.
32. AUTOMATIC ABSTRACTING RESEARCH
AT CHEMICAL ABSTRACTS SERVICE. Joseph
J. Pollock, Antonio Zamora, Chemical Information
Science Department, Chemical Abstracts Service,
The Ohio State University, Columbus, OH
43210.
This paper describes current research at Chemical
Abstracts Service into the automatic generation of abstracts
from primary documents using a modified version of the
extraction algorithm of Salvador and Zamora. The results
suggest that: (a) some subject areas are inherently more
amendable than others to automatic extraction; (b) tailoring
the algorithm for application to a narrow subject area
yields better results than attempting to apply it more generally.
The scope and viability of both the Salvador-Zamora
algorithm and of automatic extracting in general are also
discussed.
33. COMPARATIVE EVALUATION OF FACTSTHE
SIGNIFICANCE OF THE GMELIN
HANDBOOK IN MODERN SCIENCE DOCUMENTATION.
Dr. Walter Lippert, Gmelin Institute,
Postfach 900467, 6 Frankfurt/M90, West
Germany.
The function of the Gmelin Handbook of Inorganic
Chemistry is to present critically evaluated facts, based on
the original literature, and to arrange these in a comprehensive
form within the context of our entire knowledge of
a given subject. This overview differentiates the Handbook
from other literature sources, such as original papers, reviews
and abstracts which for the most part treat isolated
facts, independent of their relationship to each other and
frequently out of context with the state of the art. The
material in Gmelin is arranged by substances, i.e., according
to chemical elements and their compounds. About
90,000 text pages have been published of the current eighth
edition which is scheduled for completion by 1976. With
the ever-increasing scope of the natural sciences, it is
becoming more and more important for creative scientists
to be able to acquire a broad understanding of a given field.
Here the encyclopedic character of the handbook plays a
crucial role. Plans are currently underway to store on
magnetic tape the Handbook's detailed subject index. A
combination of Handbook and computer, thus will be
making it possible to provide to the user broad information
profiles as well as specific facts.
34. THE APPLICATION OF PATTERN RECOGNITION
TO STRUCTURE-ACTIVITY
STUDIES: On-line System for the Prediction of
the Pharmacological Activities of Drugs. Kenneth
C. Chu, Richard J. Feldmann, Melvin L. Spann.Division of Computer Research and technology,
National Institutes of Health, Bethesda, MD 20014.
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American Chemical Society. Division of Chemical Literature. Chemical Literature, Volume 27, Number 1, Spring 1975, periodical, Spring 1975; Philadelphia, Pennsylvania. (https://digital.library.unt.edu/ark:/67531/metadc5699/m1/12/: accessed April 24, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; .