The direct-chaining technique of hash coding is generalized in a manner that is useful for storing records on the basis of non-unique search keys. Two hash functions are used, a process implying a tree structure. Two models, one involving unique and the other non-unique keys, are presented. (7 references) (Author/KE)

Presents new methods for compressing bit matrices in large information retrieval systems which exploit possible correlations between rows of words and columns of documents. Three encoding methods are tested and compared--Shannon-Fano, arithmetic, and Huffman--and an appendix discusses binomial coefficients. (20 references) (LRW)