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Perfect Hashing for Network Applications

Yi Lu, Balaji Prabhakar, Flavio Bonomi
2006 2006 IEEE International Symposium on Information Theory  
This motivates us to consider minimal perfect hashing schemes, which reduce the number of memory accesses to just 1 and are also space-efficient.  ...  Our construction is several orders faster than existing perfect hashing schemes.  ...  However, a very very small subset of these functions are injective on S, and these are the minimal perfect hash functions of interest 1 .  ... 
doi:10.1109/isit.2006.261567 dblp:conf/isit/LuPB06 fatcat:sy5pitinxbcjfbsqwrfshhy4by

GigaHash

Kumar Chellapilla, Anton Mityagin, Denis Charles
2007 Proceedings of the 16th international conference on World Wide Web - WWW '07  
A minimal perfect function maps a static set of keys on to the range of integers {0,1,2, ... , − 1}.  ...  We present a scalable high performance algorithm based on random graphs for constructing minimal perfect hash functions (MPHFs).  ...  Usually, the range of the minimal perfect hash function (MPHF) is the contiguous set of integers {0,1,2, … , − 1}.  ... 
doi:10.1145/1242572.1242747 dblp:conf/www/ChellapillaMC07 fatcat:yrljzrqsenbsdjneix6rpbfhz4

Shepard: A fast exact match short read aligner

Chad Nelson, Kevin Townsend, Bhavani Satyanarayana Rao, Phillip Jones, Joseph Zambreno
2012 Tenth ACM/IEEE International Conference on Formal Methods and Models for Codesign (MEMCODE2012)  
To reduce the hash table size, a minimal perfect hash table is used.  ...  The hardware pipeline was designed to perform hash table lookups very quickly, on the order of 600 million lookups per second, and was implemented on a Convey HC-1 high performance reconfigurable computing  ...  Minimal Perfect Hash Function Shepard's solution to the large size of hash tables is to use a minimal perfect hash.  ... 
doi:10.1109/memcod.2012.6292304 dblp:conf/memocode/NelsonTRJZ12 fatcat:uq72mkh2zvdjplbqxgdbzcekoq

Minimal and almost minimal perfect hash function search with application to natural language lexicon design

Nick Cercone, Max Krause, John Boates
1983 Computers and Mathematics with Applications  
New methods for computing perfect hash functions and applications of such functions to the problems of lexicon design are reported in this paper.  ...  A discussion of conceptual designs for the application of perfect hash functions to small and large computer lexicons is followed by a summary of our research and suggestions for further work.  ...  A4309 and by the Office of the Academic Vice-President, Simon Fraser University.  ... 
doi:10.1016/0898-1221(83)90016-0 fatcat:smv7nbzjrrejhofoopdhitbbk4

Graphs, hypergraphs and hashing [chapter]

George Havas, Bohdan S. Majewski, Nicholas C. Wormald, Zbigniew J. Czech
1994 Lecture Notes in Computer Science  
We show that almost all members of the family are space and time optimal, and we identify the one with minimum constants. Members of the family generate a minimal perfect hash function in two steps.  ...  We present an infinite family of efficient and practical algorithms for generating minimal perfect hash functions which allow an arbitrary order to be specified for the keys.  ...  Acknowledgements The first and third authors were supported in part by the Australian Research Council.  ... 
doi:10.1007/3-540-57899-4_49 fatcat:3xjggn6jhfgqlm226biqvyca5i

Finding and Applying Perfect Hash Functions

Nick Cercone
1988 Applied Mathematics Letters  
The loading factor CLFJ of a hash table is the ratio of the number of keys to the table size N/r. A minimal perfect hash function maps N keys into N contiguous locations for a LF of one.  ...  This second hash function could be based on the ordinal positions of letters in the alphabet rather than on the machine character code in order to preserve machine independence.  ... 
doi:10.1016/0893-9659(88)90168-1 fatcat:n5yjvxo6efhb3ic53prfjdfgde

A faster algorithm for constructing minimal perfect hash functions

Edward A. Fox, Qi Fan Chen, Lenwood S. Heath
1992 Proceedings of the 15th annual international ACM SIGIR conference on Research and development in information retrieval - SIGIR '92  
Our previous research on one-probe access to large collections of data indexed by alphanumeric keys has produced the first practical minimal perfect hash functions for this problem.  ...  Here, a new algorithm is described for quickly finding minimal perfect hash functions whose specification space is very close to the theoretical lower bound, i.e., around 2 bits per key.  ...  , the hash function is called minimal. When both properties hold, one has a minimal perfect hash function (MPHF) as shown at the bottom of Figure 1 .  ... 
doi:10.1145/133160.133209 dblp:conf/sigir/FoxCH92 fatcat:vysmvejoxvb4vc6jcafoz4hhoy

Minimal perfect hashing: A competitive method for indexing internal memory

Fabiano C. Botelho, Anísio Lacerda, Guilherme Vale Menezes, Nivio Ziviani
2011 Information Sciences  
A minimal perfect hash function (MPHF) is a PHF with the smallest possible range, that is, the hash table size is exactly the number of keys in S.  ...  Considering space overhead (the amount of used space other than the key-value pairs), the minimal perfect hashing is within a factor of Oðlog nÞ bits lower than the other hashing schemes for both scenarios  ...  We also want to thank the reviewers for the comments that helped us to considerably improve the paper.  ... 
doi:10.1016/j.ins.2009.12.003 fatcat:ellfywyvdrepderbnjyl747tky

Flash memory efficient LTL model checking

S. Edelkamp, D. Sulewski, J. Barnat, L. Brim, P. Šimeček
2011 Science of Computer Programming  
perfect hash function from RAM to flash memory.  ...  In contrast to approaches relying on the delayed detection of duplicate states, in this work, we design and exploit appropriate hash functions to re-invent immediate duplicate detection.  ...  Acknowledgements We would like to thank Martin Dietzfelbinger for his help to derive the lower bound on perfect hashing, Peter Kissmann for his rigorous proof reading, and the anonymous reviewers for the  ... 
doi:10.1016/j.scico.2010.03.005 fatcat:5kkssybrs5dibhqgwyhvsv3xfi

Rescore in a Flash: Compact, Cache Efficient Hashing Data Structures for n-Gram Language Models

Grant P. Strimel, Ariya Rastrow, Gautam Tiwari, Adrien Piérard, Jon Webb
2020 Interspeech 2020  
We detail the algorithm and justify our design choices with comparative experiments on a speech recognition task.  ...  DashHashLM introduces several optimizations to language model compression which are designed to minimize expected memory accesses.  ...  Perfect Hashing In perfect hashing, a function maps a set S of ns keys into m buckets with no collisions. A Minimal Perfect Hash Function (MPHF) hashes S into ns buckets with no collisions.  ... 
doi:10.21437/interspeech.2020-1939 dblp:conf/interspeech/StrimelRTPW20 fatcat:djxokflyo5dtdb2v6m7xloqgr4

Scalable Multigigabit Pattern Matching for Packet Inspection

Ioannis Sourdis, Dionisios N. Pnevmatikatos, Stamatis Vassiliadis
2008 IEEE Transactions on Very Large Scale Integration (vlsi) Systems  
On the other hand, PHmem designs can support 2 to 5.7 Gbps using a few tens of block RAMs (630-1,404 Kbits) and only 0.28 to 0.65 logic cells per character.  ...  The second approach, Perfect Hashing memory (PHmem), uses perfect hashing to determine a unique memory location that contains the search pattern and a comparison between incoming data and memory output  ...  quality of this material.  ... 
doi:10.1109/tvlsi.2007.912036 fatcat:us5uiahwnrcplg5f3htjqbw2ii

An optimal algorithm for generating minimal perfect hash functions

Zbigniew J. Czech, George Havas, Bohdan S. Majewski
1992 Information Processing Letters  
A new algorithm for generating order preserving minimal perfect hash functions is presented. The algorithm is probabilistic, involving generation of random graphs.  ...  It uses expected linear time and requires a linear number words to represent the hash function, and thus is optimal up to constant factors. It runs very fast in practice.  ...  The space required to store the generated function is O(m log m) bits, which is optimal for order preserving minimal perfect hash functions (see [21] ).  ... 
doi:10.1016/0020-0190(92)90220-p fatcat:te6smawya5a57lzeelijopovtm

Perfect Hashing for Data Management Applications [article]

Fabiano C. Botelho, Rasmus Pagh, Nivio Ziviani
2007 arXiv   pre-print
We demonstrate the scalability of our algorithm by considering a set of over one billion URLs from the World Wide Web of average length 64, for which we construct a minimal perfect hash function on a commodity  ...  Though there has been considerable work on how to construct good perfect hash functions, there is a gap between theory and practice among all previous methods on minimal perfect hashing.  ...  The perfect hash function used depends on the set S of distinct attribute values that occur.  ... 
arXiv:cs/0702159v1 fatcat:7zbbgpotnneilnpfh34upd5bhe

Perfect hashing

Zbigniew J. Czech, George Havas, Bohdan S. Majewski
1997 Theoretical Computer Science  
Such a function is called an ordered minimal perfect hash fun&on.  ...  Chang and Wu considered the problem of how to design a minimal perfect hash function which is suitable for the Mandarin phonetic symbols system [26] .  ...  The rest of the symbols we use may have different meanings depending on the chapter in which the symbols occur.  ... 
doi:10.1016/s0304-3975(96)00146-6 fatcat:htaph24frffzjevl2q6kxz467e

Data-Parallel Hashing Techniques for GPU Architectures [article]

Brenton Lessley
2018 arXiv   pre-print
This study surveys the state-of-the-art research on data-parallel hashing techniques for emerging massively-parallel, many-core GPU architectures.  ...  Hash tables are one of the most fundamental data structures for effectively storing and accessing sparse data, with widespread usage in domains ranging from computer graphics to machine learning.  ...  n n , which is the probability of achieving a minimal perfect hash [75] .  ... 
arXiv:1807.04345v1 fatcat:hjqikv3wjfgahavy3lbweolhh4
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