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Scapegoat Tree
In computer science, a scapegoat tree is a self-balancing binary search tree, invented by Arne Andersson (computer scientist), Arne Andersson in 1989 and again by Igal Galperin and Ronald L. Rivest in 1993. It provides worst-case big O notation, lookup time (with n as the number of entries) and O(\log n) amortized analysis, amortized insertion and deletion time. Unlike most other self-balancing binary search trees which also provide worst case O(\log n) lookup time, scapegoat trees have no additional per-node memory overhead compared to a regular binary search tree: besides key and value, a node stores only two pointers to the child nodes. This makes scapegoat trees easier to implement and, due to data structure alignment, can reduce node overhead by up to one-third. Instead of the small incremental rebalancing operations used by most balanced tree algorithms, scapegoat trees rarely but expensively choose a "scapegoat" and completely rebuild the subtree rooted at the scapegoat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arne Andersson (computer Scientist)
Arne Andersson (27 October 1917 – 1 April 2009) was a Sweden, Swedish middle distance runner who became famous for his rivalry with his compatriot Gunder Hägg in the 1940s. Andersson set a 1500 metres world record in Gothenburg in August 1943 with a time of 3:45.0 minutes. He was born in Trollhättan Municipality, Trollhättan, Sweden. Andersson set three world records in the mile: the first in Stockholm in July 1942 in (4:06.2); this record was broken in the same year by Hägg (4:04.6). Andersson recaptured the world record in Gothenburg in July 1943 (4:02.6), and improved it further in Malmö in July 1944 (4:01.6). However, Hägg had the last word when he ran (4:01.4) in Malmö in 1945 (Hägg's record was not broken until Roger Bannister ran the first sub-4 mile in Oxford in 1954). Andersson won the Svenska Dagbladet Gold Medal in 1943. Andersson won seven national titles: two individual (1500 m, 1943–44) and five in relays (1940–42). In 1946 he was disqualified for vi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Locality Of Reference
In computer science, locality of reference, also known as the principle of locality, is the tendency of a processor to access the same set of memory locations repetitively over a short period of time. There are two basic types of reference locality temporal and spatial locality. Temporal locality refers to the reuse of specific data and/or resources within a relatively small time duration. Spatial locality (also termed ''data locality''"NIST Big Data Interoperability Framework: Volume 1"urn:doi:10.6028/NIST.SP.1500-1r2) refers to the use of data elements within relatively close storage locations. Sequential locality, a special case of spatial locality, occurs when data elements are arranged and accessed linearly, such as traversing the elements in a one-dimensional Array data structure, array. Locality is a type of predictability, predictable behavior that occurs in computer systems. Systems that exhibit strong ''locality of reference'' are great candidates for performance optimiza ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Binary Trees
In computer science, a binary tree is a k-ary k = 2 tree data structure in which each node has at most two children, which are referred to as the ' and the '. A recursive definition using just set theory notions is that a (non-empty) binary tree is a tuple (''L'', ''S'', ''R''), where ''L'' and ''R'' are binary trees or the empty set and ''S'' is a singleton set containing the root. Some authors allow the binary tree to be the empty set as well. From a graph theory perspective, binary (and K-ary) trees as defined here are arborescences. A binary tree may thus be also called a bifurcating arborescence—a term which appears in some very old programming books, before the modern computer science terminology prevailed. It is also possible to interpret a binary tree as an undirected, rather than a directed graph, in which case a binary tree is an ordered, rooted tree. Some authors use rooted binary tree instead of ''binary tree'' to emphasize the fact that the tree is rooted, but ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Massachusetts Institute Of Technology
The Massachusetts Institute of Technology (MIT) is a private land-grant research university in Cambridge, Massachusetts. Established in 1861, MIT has played a key role in the development of modern technology and science, and is one of the most prestigious and highly ranked academic institutions in the world. Founded in response to the increasing industrialization of the United States, MIT adopted a European polytechnic university model and stressed laboratory instruction in applied science and engineering. MIT is one of three private land grant universities in the United States, the others being Cornell University and Tuskegee University. The institute has an urban campus that extends more than a mile (1.6 km) alongside the Charles River, and encompasses a number of major off-campus facilities such as the MIT Lincoln Laboratory, the Bates Center, and the Haystack Observatory, as well as affiliated laboratories such as the Broad and Whitehead Institutes. , 98 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
T-tree
In computer science a T-tree is a type of binary tree data structure that is used by main memory database, main-memory databases, such as Datablitz, eXtremeDB, MySQL Cluster, TimesTen, Oracle TimesTen and MobileLite. A T-tree is a Height-balanced tree, balanced index tree data structure optimized for cases where both the index and the actual data are fully kept in memory, just as a B-tree is an index structure optimized for storage on block oriented secondary storage devices like hard disks. T-trees seek to gain the performance benefits of in-memory tree structures such as AVL trees while avoiding the large storage space overhead which is common to them. T-trees do not keep copies of the indexed data fields within the index tree nodes themselves. Instead, they take advantage of the fact that the actual data is always in main memory together with the index so that they just contain pointers to the actual data fields. The 'T' in T-tree refers to the shape of the node data struc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
B-tree
In computer science, a B-tree is a self-balancing tree data structure that maintains sorted data and allows searches, sequential access, insertions, and deletions in logarithmic time. The B-tree generalizes the binary search tree, allowing for nodes with more than two children. Unlike other self-balancing binary search trees, the B-tree is well suited for storage systems that read and write relatively large blocks of data, such as databases and file systems. Origin B-trees were invented by Rudolf Bayer and Edward M. McCreight while working at Boeing Research Labs, for the purpose of efficiently managing index pages for large random-access files. The basic assumption was that indices would be so voluminous that only small chunks of the tree could fit in main memory. Bayer and McCreight's paper, ''Organization and maintenance of large ordered indices'', was first circulated in July 1970 and later published in ''Acta Informatica''. Bayer and McCreight never explained what, if a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tree Rotation
In discrete mathematics, tree rotation is an operation on a binary tree that changes the structure without interfering with the order of the elements. A tree rotation moves one node up in the tree and one node down. It is used to change the shape of the tree, and in particular to decrease its height by moving smaller subtrees down and larger subtrees up, resulting in improved performance of many tree operations. There exists an inconsistency in different descriptions as to the definition of the direction of rotations. Some say that the direction of rotation reflects the direction that a node is moving upon rotation (a left child rotating into its parent's location is a right rotation) while others say that the direction of rotation reflects which subtree is rotating (a left subtree rotating into its parent's location is a left rotation, the opposite of the former). This article takes the approach of the directional movement of the rotating node. Illustration The right rotation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tree Data Structure
In computer science, a tree is a widely used abstract data type that represents a hierarchical tree structure with a set of connected nodes. Each node in the tree can be connected to many children (depending on the type of tree), but must be connected to exactly one parent, except for the ''root'' node, which has no parent. These constraints mean there are no cycles or "loops" (no node can be its own ancestor), and also that each child can be treated like the root node of its own subtree, making recursion a useful technique for tree traversal. In contrast to linear data structures, many trees cannot be represented by relationships between neighboring nodes in a single straight line. Binary trees are a commonly used type, which constrain the number of children for each parent to exactly two. When the order of the children is specified, this data structure corresponds to an ordered tree in graph theory. A value or pointer to other data may be associated with every node in the tre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scapegoat
In the Bible, a scapegoat is one of a pair of kid goats that is released into the wilderness, taking with it all sins and impurities, while the other is sacrificed. The concept first appears in the Book of Leviticus, in which a goat is designated to be cast into the desert to carry away the sins of the community. Practices with some similarities to the scapegoat ritual also appear in Ancient Greece and Ebla. Origins Some scholars have argued that the scapegoat ritual can be traced back to Ebla around 2400 BC, from where it spread throughout the ancient Near East. Etymology The word "scapegoat" is an English translation of the Hebrew ( he, עזאזל), which occurs in Leviticus 16:8: The Brown–Driver–Briggs Hebrew Lexicon gives () as a reduplicative intensive of the stem , "remove", hence , "for entire removal". This reading is supported by the Greek Old Testament translation as "the sender away (of sins)". The lexicographer Gesenius takes to mean "averter", wh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bible
The Bible (from Koine Greek , , 'the books') is a collection of religious texts or scriptures that are held to be sacred in Christianity, Judaism, Samaritanism, and many other religions. The Bible is an anthologya compilation of texts of a variety of forms originally written in Hebrew, Aramaic, and Koine Greek. These texts include instructions, stories, poetry, and prophecies, among other genres. The collection of materials that are accepted as part of the Bible by a particular religious tradition or community is called a biblical canon. Believers in the Bible generally consider it to be a product of divine inspiration, but the way they understand what that means and interpret the text can vary. The religious texts were compiled by different religious communities into various official collections. The earliest contained the first five books of the Bible. It is called the Torah in Hebrew and the Pentateuch (meaning ''five books'') in Greek; the second oldest part was a coll ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aggregate Analysis
In computer science, amortized analysis is a method for analyzing a given algorithm's complexity, or how much of a resource, especially time or memory, it takes to execute. The motivation for amortized analysis is that looking at the worst-case run time can be too pessimistic. Instead, amortized analysis averages the running times of operations in a sequence over that sequence. As a conclusion: "Amortized analysis is a useful tool that complements other techniques such as worst-case and average-case analysis." For a given operation of an algorithm, certain situations (e.g., input parametrizations or data structure contents) may imply a significant cost in resources, whereas other situations may not be as costly. The amortized analysis considers both the costly and less costly operations together over the whole sequence of operations. This may include accounting for different types of input, length of the input, and other factors that affect its performance. History Amortized ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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