61. Data & Procedure: Hashing While trees are a useful data structure for implementing the Set ADT, practitioners tend to use the hash table instead. A tree maintain its elements in http://www.toves.org/books/data/ch06-hash/index.html

Contents 1. Introduction 2. Recursion and lists 3. Reasoning about correctness ... 5. Trees 6. Hashing 7. Stacks and queues 8. Priority queues 9. Java review Chapter 6. Hashing While trees are a useful data structure for implementing the Set ADT, practitioners tend to use the hash table instead. A tree maintain its elements in order, which is useful in some cases. Hash tables do not maintain any order; this flexibility, as we shall see, results in an opportunity for improved speed. Before investigating the technique of hashing, though, we'll first examine the important Map ADT, another ADT for which both trees and hashing are useful. 6.1. The Map ADT mapping from some collection of objects to another set of objects. 6.1.1. Lookup tables Before we look at the general Map ADT, we first consider a simple structure called a lookup table . Here, we use an array to associate values with a small range of integers. An example involving a lookup table would be a program to compute the mode O n n test scores. We can improve this dramatically, still without using a lookup table, by sorting the list: After sorting, all repeated scores will be adjacent to one another, and we have only to go through the sorted list to find the longest sequence. Sorting the list takes O n log n ) time, and finding the longest sequence takes

62. Athens HHH - Hashing Weekends Click for listing of past hashing weekends Registration form downloading help 0406 May 2007 hashing Island Weekend Island of Mykonos in the main town http://www.athenshash.com/Main_HTML/weekends.htm

Hashing Weekends in Greece Click for listing of past hashing weekends Registration form downloading help Watch This Space info@athenshash.com If you are stopping in Athens: Cheap accommodation in the centre... (NOTE: Most of our hashers live way out from the centre - in the Northern or Southern suburbs - away from tourist spots) This is a great place to stay to do some quick sightseeing and tour the tourist areas, bars, etc. ATHENS BACKPACKERS 12 Makri Street, Athens 117 42 (beside the Acropolis metro) (Take metro exit on right, to Athinas Diachou, walk down this street 30 metres, then left into Makri St.) Tel: +30-210-922-4044 Fax: +30-210-922-4040 E-mail: info@backpackers.gr Web: http://www.backpackers.gr .... From 15 Euro per night (2004) Don't forget to book! Examples of Some Past Hash Weekends 04-06 May 2007 Hashing Island Weekend Island of Mykonos in the main town 3 runs 15-17 Sep 2006 Hashing Island Weekend Island of Evia in Eretria town 3 runs 26-28 May 2006 Hashing Weekend in Tyros, Peloponissos

63. Hash Function - Wikipedia, The Free Encyclopedia A hash function 1 is a reproducible method of turning some kind of data into a (relatively) small number that may serve as a digital fingerprint of the http://en.wikipedia.org/wiki/Hash_function

Hash function From Wikipedia, the free encyclopedia Jump to: navigation search A hash function is a reproducible method of turning some kind of data into a (relatively) small number that may serve as a digital "fingerprint" of the data. The algorithm "chops and mixes" (i.e., substitutes or transposes) the data to create such fingerprints. The fingerprints are called hash sums hash values hash codes or simply hashes . (Note that hashes can also mean the hash functions.) Hash sums are commonly used as indices into hash tables or intermediate hash files. Cryptographic hash functions are used for various purposes in information security applications. A typical hash function at work Contents Properties Applications Cryptography Hash tables ... edit Properties Hash functions are designed to be fast and to yield few hash collisions in expected input domains. In hash tables and data processing , collisions inhibit the distinguishing of data, making records more costly to find. A hash function must be deterministic , i.e. if two hashes generated by the same hash function are different, then the two inputs were different in some way. Hash functions are usually not injective , i.e. the computed hash value may be the same for different input values. This is because it is usually a requirement that the hash value can be stored in fewer bits than the data being hashed. It is a design goal of hash functions to minimize the likelihood of such a

64. An Illustrated Guide To Cryptographic Hashes This demonstrates that no matter how big the input stream is, the generated hash is the same size (but of course, not the same value). http://unixwiz.net/techtips/iguide-crypto-hashes.html

Does this site look plain? This site uses advanced css techniques Steve Friedl's Unixwiz.net Tech Tips An Illustrated Guide to Cryptographic Hashes Contact About TechTips Evo Payroll ... My Weblog Moved! This website recently changed hosts, so there may be stuff that didn't make the trip. Please send me a note if you notice such. With the recent news of weaknesses in some common security algorithms (MD4, MD5, SHA-0), many are wondering exactly what these things are: They form the underpinning of much of our electronic infrastructure, and in this Guide we'll try to give an overview of what they are and how to understand them in the context of the recent developments. Table of Contents What is a cryptographic hash? Hashes are "digests", not "encryption" How are hashes used? But what about collisions? ... Other voices But note: though we're fairly strong on security issues, we are not crypto experts. We've done our best to assemble (digest?) the best available information into this Guide, but we welcome being pointed to the errors of our ways. What is a cryptographic hash?

65. World Hash House Harriers Home Page World s largest resource for the Hash House Harriers, a social hounds and hare running and bicycling club with groups in every major city in the world. http://www.gthhh.com/

World HHH Market Global Trash InterHASHional News presents The World Hash House Harriers Home Page 18326 Members and Climbing - Are You? Welcome to the home page for the world's most eccentric running club, the Hash House Harriers . Now with 1849 hash groups registered in the world directory located in almost every major city in the world and 178 countries , it is easier than ever for you to find fun, trail, and friendship where you live. The Hash House Harriers is a more social version of Hare and Hounds, where you join the pack of hounds (runners) to chase down the trail set by the hare or hares (other runners) , then gather together for a bit of social activity known as the On In or Down Down with refreshment, humor, song and sometimes a feast. In most groups, all are welcome, young and old, fast or slow, so don't wait to get in shape , just come on out and join us. The only prerequisite to hashing is a sense of humor, so check out a hash near you by clicking on the World Directory button, search for the group nearest you and ring up or email one of the contacts listed there. It's that simple. If you do not know anything about the Hash House Harriers and would like to read up on us, or if you cannot find a group near you and are thinking of starting one, click on the

66. This Is The Home Page Of The Atlanta Hash House Harriers And Harriettes This is the Web Site for the Atlanta Hash House Harriers and Harriettes AH4 for Short - We Run and Drink Beer Every Saturday at 130 PM, and Virgins get http://www.atlantahash.com/

Welcome To The Atlanta Hash! The Atlanta Hash House Harriers and Harriettes, (AH4) is a Social Running Club that emphasizes fun (beer) more than competition. Our goal is pretty simple - get a little exercise, drink some beer, give each other a hard time, and bitch about stuff with four-letter words. Founded in 1982 , the Atlanta Hash was the first hash to hit the great state of Georgia, and we've given birth to many other chapters near and far. We don't take ANY responsibility for these ne'er-do-wells, but if you can't hash with us for some stooopid reason, we suggest giving them a look-see . Just don't expect any of them to be as cool as us. At one of our fine hashes, which generally meet each

67. Hash Function Definition of hash function, possibly with links to more information and implementations. http://www.nist.gov/dads/HTML/hash.html

hash function (algorithm) Definition: A function that maps keys to integers, usually to get an even distribution on a smaller set of values. Specialization (... is a kind of me.) different kinds: linear hash perfect hashing minimal perfect hashing order preserving minimal perfect hashing , specific functions: Pearson's hash multiplication method Aggregate parent (I am a part of or used in ...) hash table uniform hashing universal hashing Bloom filter See also simple uniform hashing Note: The range of integers is typically [0... m-1] where m is a prime number or a power of 2. Author: PEB Implementation See the implementations at minimal perfect hashing (C++ and C) and Pearson's hash (C) . Bob Jenkins' fast, parameterizable, broadly applicable hash function (C) including code for and evaluations of many other hash functions. A review and comparison of many integer hash functions (C) . Overview of different kinds of hash functions . Bret Mulvey's great tutorial on good hash functions, including analysis of and code for FNV, Jenkin's hashes, SHA-1, and other hash and evaluation functions (C#)

68. Perl.com: How Hashes Really Work Ahbijit explains what a hash actually is, and how they work. http://www.perl.com/pub/a/2002/10/01/hashes.html

Articles ONLamp Weblog Books Courses ... Podcasts var addthis_pub = 'odewahn'; Listen Print Subscribe to Perl.com How Hashes Really Work by Abhijit Menon-Sen October 01, 2002 It's easy to take hashes for granted in Perl. They are simple, fast, and they usually "just work," so people never need to know or care about how they are implemented. Sometimes, though, it's interesting and rewarding to look at familiar tools in a different light. This article follows the development of a simple hash class in Perl in an attempt to find out how hashes really work. A hash is an unordered collection of values, each of which is identified by a unique key. A value can be retrieved by its key, and one can add to or delete from the collection. A data structure with these properties is called a dictionary, and some of the many ways to implement them are outlined below. Related Reading Programming Perl By Larry Wall Tom Christiansen Jon Orwant Table of Contents ... Read OnlineSafari Search this book on Safari: Only This Book All of Safari Code Fragments only Many objects are naturally identified by unique keys (like login names), and it is convenient to use a dictionary to address them in this manner. Programs use their dictionaries in different ways. A compiler's symbol table (which records the names of functions and variables encountered during compilation) might hold a few hundred names that are looked up repeatedly (since names usually occur many times in a section of code). Another program might need to store 64-bit integers as keys, or search through several thousands of filenames.

69. FNV Hash The basis of the FNV hash algorithm was taken from an idea sent as reviewer comments to the IEEE POSIX P1003.2 committee by Glenn Fowler and Phong Vo. http://isthe.com/chongo/tech/comp/fnv/index.html

Fowler / Noll / Vo (FNV) Hash Mathematics / Cryptology / Cryptography pages Computer / Algorithm pages Technology pages chongo's home page Search the entire web Search only www.isthe.com FNV quick index History and use of the FNV hash The FNV-1 hash in a nutshell The FNV-1a hash minor variation FNV-1 hash parameters Changing the FNV hash size with xor-folding FNV hash with a non-power of 2 size Portable FNV hashing of numeric values Extended FNV type hashing Sample FNV source code A slight gcc optimization top FNV hash history The basis of the FNV hash algorithm was taken from an idea sent as reviewer comments to the IEEE POSIX P1003.2 committee by Glenn Fowler and Phong Vo . In a subsequent ballot round: Landon Curt Noll improved on their algorithm. Some people tried this hash and found that it worked rather well. In an EMail message to Landon, they named it the `` Fowler/Noll/Vo '' or FNV hash. FNV hashes are designed to be fast while maintaining a low collision rate. The FNV speed allows one to quickly hash lots of data while maintaining a reasonable collision rate. The high dispersion of the FNV hashes makes them well suited for hashing nearly identical strings such as URLs, hostnames, filenames, text, IP addresses, etc.

70. World Hash Links Traveling Hasher s Information Resource, National and Regional Hash House Harriers Link Page Go to the Hash!!! All the resources needed to hash around the http://gotothehash.net/

Contact Links Map Africa Map Arabian Gulf ... Viet Nam Features Hash T-Shirt Museum Hash Web Kit Hash History Hash Humor ... Travel Resource World Hash Events World Hash Events Calendar Worldwide Hash Events Also: AUS NZ UK Red Dress Links Interhash Info Interhash - 2008: Perth Bali - 2010 Bid Borneo - 2010 Bid Durban - 2010 Bid (pending) Kenya - 2010 Bid Malaysia - 2010 Bid IntraContinental Hash Events EuroHash 2009 - Turkey IndoChina Mekong 2007 - Viet Nam InterAmericas 2009 - Colorado InterAfrica 2009 - Uganda InterGulf 2009 - ? InterScandi 2009 - Norway PanAsia 2009 - Philippines South Asia 2007 - Sri Lanka Check the Latest Info Nash Hash Events Australia (May 09) Belgium (May 08) Borneo (Nov 09) Canada (OVER) China (OVER) Dutch (May 08) Germany (OVER) India (Mar 08) Indonesia (OVER) Japan (May 08) Korea (OVER) Malaysia (May 08) New Zealand (Feb 09) Philippines (Jan 09) Sweden (OVER) Switzerland (Aug 08) Turkey (OVER) United Kingdom (OVER) United States (May 08) Read Hash-L Monday Tuesday Wednesday Thursday ... Hash-L FAQ Other Hash-L Subscribe Read Before You Post Check E-Mail AOL G-Mail Hotmail Yahoo Maps Google MapQuest Yahoo Information Links Asia-Pacific Harrier Magazine Digital Hash T-Shirt Museum Founder's Hash Half Mind Catalog ... Harrier.net

71. Hash Table: Information And Much More From Answers.com hash table A lookup table that is designed to efficiently store noncontiguous keys (account numbers, part numbers, etc.) that may have wide gaps in. http://www.answers.com/topic/hash-table

BodyLoad('s'); Results for Hash Table On this page: Select Article Computer Ency. Wikipedia Best of Web Or search: - The Web - Images - News - Blogs - Shopping Computer Encyclopedia hash table A lookup table that is designed to efficiently store non-contiguous keys (account numbers, part numbers, etc.) that may have wide gaps in their alphabetic and numeric sequences. Hash tables are created by using a hashing function (algorithm) to hash the keys into hash buckets. Each bucket is a list of key value pairs. Since different keys may hash to the same bucket, the goal of hash table design is to spread out the key-value pairs evenly with each bucket containing as few key-value pairs as possible. When an item is looked up, its key is hashed to find the appropriate bucket. Then, the bucket is searched for the right key-value pair. If access to the values is desired other than through the keys, an indexing system can be built on top of a hash table. Such user-level search engines can be made to handle imprecise queries and misspellings. See key-value pair and DHT A Hash Table When an item is looked up, its key is hashed into a hash value that becomes the index into the bucket. Then, the bucket is searched for the right key-value pair.

72. Middle Georgia Hash House Harriers Middle Georgia s local crosscountry running club with a drinking problem! A great way to spice up your jogging, walking, or running routine. http://mgh4.com/

Proudly contributing to the decline of civilization in Middle Georgia! 'DRINKING CLUB WITH A RUNNING PROBLEM'. Anyone who wants to have some fun, drink some beer, and get a bit of exercise, can put on their running shoes and meet us for the next trail. There is no formal membership and we LOVE new people to come out and join us!!! We normally run every other week on Saturday or Sunday around 3pm. Afterwards, we often meet for dinner at a local restaurant. Your first run is free ("come on kid, first time's free...") thereafter the price is a measly $6.00 for all the beer (or soft drinks/water) snacks and general camaraderie you can stand! All it takes to be a hasher is a good sense of humor, an interest in the outdoors, and half a mind! Sound like fun? Wanna know more? Check out the "So what is hashing" button to your left! A completely unofficial, unrequested, unnecessary, uncouth and unfunded Homepage Visitor #

73. Jax Beach Hash House Harriers Jax Hash 8 Sat, 01/19/2008 Hare(s) Cirrohsis Sphincter. Time 200pm HST Jax Beach Hash 515 Wed, 01/23/2008 Hare(s) Tom A Cock Chop http://www.jaxh3.com/

MENU Home What is Hashing? Shiggy Meter Hash Calendar ... Admin Page HASH INFO For Wednesdays Kerb Crawler JaxH3 Yahoo Groups Message Board KGB KGB Messages KGB Photos Jax Beach Hash House Harriers A Drinking Club with a Running Problem Recent Trash All Trashes Recent Photos NEXT LOCAL HASH Jax Beach Hash #516 Wed, 01/30/2008 : Hare(s): Hops on Pops To Be Announced... Mardi Gras Anyone? SPECIAL EVENTS Mardi Gras Madness XVIII -FeBREWary 5th LOLLA BUD ZOOLA FeBREWary 9th Daytona Bike Week, Feb 29 - Mar 2 USA NASH Hash 2008, 23-26MAY08 JANUARY VOTES PRIOR MONTHS 4 Votes 1 Votes 1 Votes December November October

74. SparkNotes: Hash Tables: What Is A Hash Table? A hash table is made up of two parts an array (the actual table where the data to be searched is stored) and a mapping function, known as a hash function. http://www.sparknotes.com/cs/searching/hashtables/section1.html

saveBookmark("", "", ""); Shopping Cart Checkout Home Computer Science Study Guides ... Hash Tables : What is a Hash Table? - Navigate Here - Introduction and Summary Terms What is a Hash Table? Problems Hash Functions Problems Coding up a Hash Table Problems Another use of hashing: Rabin-Karp string searching Problems What is a Hash Table? As we saw with binary search , certain data structures such as a binary search tree can help improve the efficiency of searches. From linear search to binary search , we improved our search efficiency from O n to O logn . We now present a new data structure , called a hash table, that will increase our efficiency to O , or constant time A hash table is made up of two parts: an array (the actual table where the data to be searched is stored) and a mapping function, known as a hash function. The hash function is a mapping from the input space to the integer space that defines the indices of the array. In other words, the hash function provides a way for assigning numbers to the input data such that the data can then be stored at the array index corresponding to the assigned number. Let's take a simple example. First, we start with a hash table array of strings (we'll use strings as the data being stored and searched in this example). Let's say the hash table size is 12:

75. Tree Hash EXchange Format (THEX) This memo presents the Tree Hash Exchange (THEX) format, for exchanging Merkle Hash Trees built up from the subrange hashes of discrete digital files. http://open-content.net/specs/draft-jchapweske-thex-02.html

TOC J. Chapweske Onion Networks, Inc. G. Mohr Bitzi, Inc. March 4, 2003 Tree Hash EXchange format (THEX) Abstract This memo presents the Tree Hash Exchange (THEX) format, for exchanging Merkle Hash Trees built up from the subrange hashes of discrete digital files. Such tree hash data structures assist in file integrity verification, allowing arbitrary subranges of bytes to be verified before the entire file has been received. TOC Table of Contents Introduction Merkle Hash Trees Hash Functions Unbalanced Trees Choice Of Segment Size Serialization Format DIME Encapsulation XML Tree Description File Size File Segment Size Digest Algorithm Digest Output Size Serialized Tree Depth Serialized Tree Type Serialized Tree URI Breadth-First Serialization Serialization Type URI Authors' Addresses A. Test Vectors TOC 1. Introduction The Merkle Hash Tree, invented by Ralph Merkle, is a hash construct that exhibits desirable properties for verifying the integrity of files and file subranges in an incremental or out-of-order fashion. This document describes a binary serialization format for hash trees that is compact and optimized for both sequential and random access. This memo has two goals: To describe Merkle Hash Trees and how they are used for file integrity verification.

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