The study of letter-oriented hashing schemes
Abstract This article proposes two minimal perfect hashing schemes suitable for letter-oriented keys. One is based on the Chinese remainder theorem, and the other is based on Ghosh's rank-hashing function. The most significant advantages of these two schemes are that it is not necessary to arrange the extracted character pairs in their lexical order, the extraction job can be done by computer (an algorithm for automatic extraction is proposed here to solve this problem), the extraction can be extended from character pairs to character triplets, quartets, or quintets such that the occurrence of key collision may decrease or even not occur, and both schemes can handle a very large number of letter-oriented keys.