Some elementary mathematical properties of term matching document retrieval systems are developed. These properties are used as a basis for a new file organization technique. Some of the advantages of this new method are (1) the key-to-address transformation is easily determined; (2) the documentary information is stored only once in the file; (3) the file organization allows the use of various matching functions and thresholds; and (4) the dimensionality of the transform is easily expanded to accommodate various sized data bases.

Threshold-type retrieval functions have been suggested by many people and used widely in clustering algorithms. In this paper, a discriminating capacity is defined for these retrieval functions. Explicit methods for computation are presented. The discriminating capacity is useful as a quantitative measure for the retrieval power of each function and can serve as a guide for selection.