Hash, Displace, and Compress

A hash function h, i.e., a function from the set U of all keys to the range range [m] = {0, . . . , m − 1} is called a perfect hash function (PHF) for a subset S ⊆ U of size n ≤ m if h is 1–1 on S. The important performance parameters of a PHF are representation size, evaluation time and construction time. In this paper, we present an algorithm that permits to obtain PHFs with representation size very close to optimal while retaining O(n) construction time and O(1) evaluation time. For example in the case m = 2n we obtain a PHF that uses space 0.67 bits

• Type: Conference
• Year: 2009
• Where: ESA
• Authors: Djamal Belazzougui, Fabiano C. Botelho, Martin Dietzfelbinger
• Keywords: Algorithms, ESA 2009, Hash Function, Hash Function H, Representation Size