Gordon V. Cormack’s research while affiliated with University of Victoria and other places

Authors of papers on LR parser table compaction and authors of books on compiler construction appear to have either overlooked or discounted the possibility of using hashing. It is argued that hashing is easy to implement as a compaction technique and gives reasonable performance. It produces tables that are as compact as some of the other techniques reported in the literature while permitting efficient table lookups.

A general-purpose data-compression routine—implemented on the IMS database system—makes use of context to achieve better compression than Huffman's method applied character by character. It demonstrates that a wide variety of data can be compressed effectively using a single, fixed compression routine with almost no working storage.

A practical method is presented that permits retrieval from a table in constant time. The method is suitable for large tables and consumes, in practice, O(n) space for n table elements. In addition, the table and the hashing function can be constructed in O(n) expected time. Variations of the method that offer different compromises between storage usage and update time are presented.

L'algorithme d'Huffman permet de generer des codes a redondance minimum pour un ensemble fini de message a frequences de transmissions connues. On considere ici seulement les codes d'Huffman binaires. On decrit un algorithme qui peut etre generalise, mais le systeme binaire reste certainement le mieux adapte aux applications informatiques