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A Comparison of Hashing Schemes for Address Lookup in Computer Networks
, 1989
"... The trend toward networks becoming larger and faster, and addresses increasing in size, has impelled a need to explore alternatives for fast address recognition. Hashing is one such alternative which can help minimize the address search time in adapters, bridges, routers, gateways, and name servers. ..."
Abstract

Cited by 45 (1 self)
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The trend toward networks becoming larger and faster, and addresses increasing in size, has impelled a need to explore alternatives for fast address recognition. Hashing is one such alternative which can help minimize the address search time in adapters, bridges, routers, gateways, and name servers. Using a trace of address references, we compared the efficiency of several different hashing functions and found that the cyclic redundancy checking (CRC) polynomials provide excellent hashing functions. For software implementation, Fletcher checksum provides a good hashing function. Straightforward folding of address octets using the exclusiveor operation is also a good hashing function. For some applications, bit extraction from the address can be used. Guidelines are provided for determining the size of hash mask required to achieve a specified level of performance.
An Optimal Algorithm for Generating Minimal Perfect Hash Functions
 Information Processing Letters
, 1992
"... 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 facto ..."
Abstract

Cited by 42 (0 self)
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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. Keywords: Data structures, probabilistic algorithms, analysis of algorithms, hashing, random graphs
Application of Minimal Perfect Hashing in Main Memory Indexing
, 1994
"... With the rapid decrease in the cost of random access memory (RAM), it will soon become economically feasible to place fulltext indexes of a library in main memory. One essential component of the indexing system is a hashing algorithm, which maps a keyword into the memory address of the index inform ..."
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Cited by 2 (0 self)
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With the rapid decrease in the cost of random access memory (RAM), it will soon become economically feasible to place fulltext indexes of a library in main memory. One essential component of the indexing system is a hashing algorithm, which maps a keyword into the memory address of the index information corresponding to that keyword. This thesis studies the application of the minimal perfect hashing algorithm in main memory indexing. This algorithm is integrated into the index search engine of the Library 2000 system, a digital online library system. The performance of this algorithm is compared with that of the openaddressing hashing scheme. We find that although the minimal perfect hashing algorithm needs fewer keyword comparisons per keyword search on average, its hashing performance is slower than the openaddressing scheme.
Abbreviated Dynamic Source Routing: Source Routing with NonUnique Network Identifiers ∗
"... Current adhoc network protocols are designed for hosts similar to the ones that are used in fixed networks. These protocols are not suitable for some applications of adhoc networks, where resources are very scarce. One point is the size of the network addresses, which may be a critical issue, spec ..."
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Cited by 1 (1 self)
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Current adhoc network protocols are designed for hosts similar to the ones that are used in fixed networks. These protocols are not suitable for some applications of adhoc networks, where resources are very scarce. One point is the size of the network addresses, which may be a critical issue, specially with the use of IPv6 in the DSR protocol. This is because this protocol uses source routing, and, therefore, each datagram must carry the addresses of all the machines in its path. In this paper a new protocol named ADSR is proposed to solve this problem. This new protocol is a modified version of DSR based on the use of abbreviated addresses. The abbreviation procedure can lead to two different nodes having the same address, which we will term collision. ADSR allows rather than averts collisions, as analysed in this paper. Some results on the performance of this new protocol are shown. These results have been obtained by simulations implemented on an ns2 network simulator. 1. AdHoc Networks Adhoc networks are computer networks that are set up when needed. These networks are composed of the hosts that happen to be in the right place at the right time, and have no fixed infrastructure, like, for instance, the Internet. Wireless links, battery power and the right algorithms free these networks from the need for wires, access points, routers or external power [12]. These networks are made up of similar nodes with no hierarchy. Each host is able to produce, route and consume data. Preferably they should not need the assistance of any user or human administrator either.
Submitted to the Department of Electrical Engineering and
, 1999
"... In recent years, the recognition of handwritten mathematical expressions has recieved an increasing amount of attention in pattern recognition research. The diversity of approaches to the problem and the lack of a commercially viable system, however, indicate that there is still much research to be ..."
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In recent years, the recognition of handwritten mathematical expressions has recieved an increasing amount of attention in pattern recognition research. The diversity of approaches to the problem and the lack of a commercially viable system, however, indicate that there is still much research to be done in this area. In this thesis, I will describe an online approach for converting a handwritten mathematical expression into an equivalent expression in a typesetting command language such as T E X or MathML, as well as a feedbackoriented user interface which can make errors more tolerable to the end user since they can be quickly corrected.