MONO91 Table of Contents table of contents Mary Elizabeth Stevens National Bureau of Standards Contents Abstract Introduction 1 1.1 Definitions and background 2 1.2 Scope of this study 10 1.3 Derivative vs. assignment indexing 13 2. Indexes compiled by machine 14 2. 1 Concordances and complete text processing 15 2.2 Card catalogs, book catalogs, bibliographies and subject index listings prepared by machine 19 2.3 Tabledex and other special purpose indexes 25 2.4 Citation indexes 27 2.5 Machine conversion from one index set to another 38 3. Indexes generated by machine - automatic derivative indexing 40 3.1 KWIC indexes 40 3.1.1 Applications of KWIC indexing techniques 41 3.1.2 Advantages, disadvantages and operational problems of KWIC indexing 55 3.2 Modified derivative indexing 68 3.2.1 Title augmentation 68 3.2.2 Book indexing by computer 71 3.2.3 Modified derivative indexing - Baxendale's experiments 73 3.3 Derivative indexing from automatic abstracting techniques 75 3.3.1 Auto-condensation and auto-encoding techniques of H. P. Luhn 75 3.3.2 Frequencies of word n-tuples - Oswald and others 79 3.3.3 Relative frequency techniques - Edmundson and Wyllys3 and others 81 3.3.4 Significant word distances 83 3.3.5 Uses of special clues for selection 84 3.3.6 Recent examples of mixed systems experimentation 86 3.4 Quality of modified derivative indexing by machine 89 4. Automatic assignment indexing techniques 91 4.1 Swanson and later work at Thompson Ramo Wooldridge 91 4.2 Maron's automatic indexing experiments 93 4.3 Automatic indexing investigations of Borko and Bernick 94 4.4 Williams' discriminant analysis method 97 4.5 SADSACT 98 4.6 Assignment indexing from citation data 99 4.7 Similarities and distinctions among assignment indexing experiments 100 4.8 Other assignment indexing proposals 105 iv