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Data structure

In computer science, a data structure is a data organization and storage format that enables efficient access and modification. More a data structure is a collection of data values, the relationships among them, the functions or operations that can be applied to the data. Data structures serve as the basis for abstract data types; the ADT defines the logical form of the data type. The data structure implements the physical form of the data type. Different types of data structures are suited to different kinds of applications, some are specialized to specific tasks. For example, relational databases use B-tree indexes for data retrieval, while compiler implementations use hash tables to look up identifiers. Data structures provide a means to manage large amounts of data efficiently for uses such as large databases and internet indexing services. Efficient data structures are key to designing efficient algorithms; some formal design methods and programming languages emphasize data structures, rather than algorithms, as the key organizing factor in software design.

Data structures can be used to organize the storage and retrieval of information stored in both main memory and secondary memory. Data structures are based on the ability of a computer to fetch and store data at any place in its memory, specified by a pointer—a bit string, representing a memory address, that can be itself stored in memory and manipulated by the program. Thus, the array and record data structures are based on computing the addresses of data items with arithmetic operations, while the linked data structures are based on storing addresses of data items within the structure itself; the implementation of a data structure requires writing a set of procedures that create and manipulate instances of that structure. The efficiency of a data structure cannot be analyzed separately from those operations; this observation motivates the theoretical concept of an abstract data type, a data structure, defined indirectly by the operations that may be performed on it, the mathematical properties of those operations.

There are numerous types of data structures built upon simpler primitive data types: An array is a number of elements in a specific order all of the same type. Elements are accessed using an integer index to specify. Typical implementations allocate contiguous memory words for the elements of arrays. Arrays may be resizable. A linked list is a linear collection of data elements of any type, called nodes, where each node has itself a value, points to the next node in the linked list; the principal advantage of a linked list over an array, is that values can always be efficiently inserted and removed without relocating the rest of the list. Certain other operations, such as random access to a certain element, are however slower on lists than on arrays. A record is an aggregate data structure. A record is a value that contains other values in fixed number and sequence and indexed by names; the elements of records are called fields or members. A union is a data structure that specifies which of a number of permitted primitive types may be stored in its instances, e.g. float or long integer.

Contrast with a record, which could be defined to contain a float and an integer. Enough space is allocated to contain the widest member datatype. A tagged union contains an additional field indicating its current type, for enhanced type safety. An object is a data structure that contains data fields, like a record does, as well as various methods which operate on the data contents. An object is an in-memory instance of a class from a taxonomy. In the context of object-oriented programming, records are known as plain old data structures to distinguish them from objects. In addition and binary trees are other used data structures. Most assembly languages and some low-level languages, such as BCPL, lack built-in support for data structures. On the other hand, many high-level programming languages and some higher-level assembly languages, such as MASM, have special syntax or other built-in support for certain data structures, such as records and arrays. For example, the C and Pascal languages support structs and records in addition to vectors and multi-dimensional arrays.

Most programming languages feature some sort of library mechanism that allows data structure implementations to be reused by different programs. Modern languages come with standard libraries that implement the most common data structures. Examples are the C++ Standard Template Library, the Java Collections Framework, the Microsoft. NET Framework. Modern languages generally support modular programming, the separation between the interface of a library module and its implementation; some provide opaque data types. Object-oriented programming languages, such as C++, Smalltalk use classes for this purpose. Many known data structures have concurrent versions which allow multiple computing threads to access a single concrete instance of a data structure simultaneously. Peter Brass, Advanced Data Structures, Cambridge University Press, 2008, ISBN 978-0521880374 Donald Knuth, The Art of Computer Prog

Ethel Moir

Ethel Mary Moir, a nursing orderly who served with the Scottish Women's Hospitals for Foreign Service on the Eastern Front during World War I. Moir recorded her experiences serving with the Elsie Inglis Unit in Russia and Serbia in two volumes of diaries. Ethel Mary Moir was born in 1884 in Belize in British Honduras, one of five children born to Dr John Moir and his wife Jessie. Moir left British Honduras at the age of 3 months and travelled with her family to Scotland where she grew up in Inverness and befriended Lilias Mary Grant. Moir is recorded as residing in Inverness with her family in both the 1911 census. In 1916, Moir and Grant enlisted with Dr Elsie Inglis unit of the Scottish Women's Hospitals for Foreign Service, known as the SWH, the two women embarked on the troopship Hanspiel in Liverpool, sailing from there to the port of Arkhangelsk in Russia. While aboard ship Moir began recording her experiences in a diary and scrapbook which she kept for the next three years. Moir notes in her diary that the ship arrived in Arkhangelsk on 10 September 1916 and from there the unit moved upriver to Bacheridza where they were visited by local dignitaries.

While in the area Moir and Grant visited a local village and Moir recorded a number of local words and customs in her diary. The unit left Bacheridza by train and travelled via Moscow to the Front where they joined the First Serbian Volunteer Division in Odessa and set up a field hospital in a barn housing 200 injured soldiers. In her diary, Muir records that the field hospital had no lighting and that water had to be carried from a pump on a hillside some distance away. In late September Moir and the SWH moved to Medgidia, close to the front line, where they set up a hospital treating both Serbian and Russian troops. By the end of 1916 Moir's unit returned to Odessa and established a hospital where Moir worked in the theatre. In January 1917 Moir and Grant left the Front to return to Scotland, a journey that took three months, they passed through Petrograd where Moir records in her diary that people were dying of starvation and there was talk of revolution and the death of Rasputin. Ethel arrived back in Scotland in March 1917, her ship having been diverted to Lerwick as it was carrying a cargo of zinc-spelter for munitions.

In February 1918, Ethel embarked on a second tour of duty with the Scottish Women's Hospital. Before leaving the UK the unit was inspected by King George Queen Mary at Buckingham Palace. Ethel left the UK with her unit on 20 February 1918 en route for Serbia, they travelled via Boulogne, Rome and Taranto before arriving at the Scottish Women's Hospital in Salonique. While passing through Naples Ethel records a short visit to Pompeii in her diary. From Thesaloniki the unit moved on to S. W. H. “Elsie Inglis” Camp in Verbliani where a tent hospital was to be built as a direct line from the trenches. Moir and Grant's war time experiences, as recorded in their diaries, inspired the play Sea And Land And Sky by Abigail Docherty.'There’s a Long Long Trail A-Winding' - Tales Of One City blog from Edinburgh City Council detailing Ethel Moir's diary. Images from Ethel Moir's diaries on the Capital Collections website

Fran├žoise d'Eaubonne

Françoise d'Eaubonne was a French feminist, who introduced the term "ecofeminism" in 1974. Her mother was a child of a Carlist revolutionary, her father was a member of an anarchist sympathiser. Her childhood in Toulouse was marked by the physical decay of her father, due to the gas he had been exposed to in the trenches during the war in 1914; when she was at the age of 16, the Spanish Civil War broke out. Three years she witnessed the arrival of the Republicans in exile. Between the age of 20 and 25, she endured the privations of the time. In a railway station in Paris, the Liberation, the end of the war, met her in the form of freed Jews returning from the camps, she would express her feelings in this period of her life with the meaningful title "Chienne de Jeunesse". Such a childhood, together with a hypersensitive personality, made her look at the world critically, formed her into a militant radical and feminist. A former member of the French Communist Party, in 1971, she co-founded the Front homosexuel d'action révolutionnaire, a homosexual revolutionary movement.

That year, she signed the Manifesto of the 343 declaring she had an abortion. She is considered the founder of the social movement of ecofeminism, she created the Ecology-Feminism Center in Paris in 1972. In 1974 she published her book Le féminisme ou la mort. In the book she speaks of a special connection women share with nature and encourages women's environmental activism, she cites toxic masculinity as the cause of population growth and other destructive influences on the environment. Many scholars shared d'Eaubonne's view on women's inherent connection to nature; these scholars include Sherry Ortner, Rosemary Radford Ruether, Susan Griffin, Carolyn Merchant. In her literary and militant life, she came across a number of people of influence in the 20th century, like Colette, Simone de Beauvoir, Jean-Paul Sartre, Jean Cocteau, many more. Following her motto, "Not a day without a line", Françoise d'Eaubonne wrote more than 50 works, from Colonnes de l'âme to L'Évangile de Véronique, her historical novel Comme un vol de gerfauts was translated into English as A Flight of Falcons, extracts from her essay Feminism or Death appeared in the 1974 anthology New French Feminisms.

She wrote science fiction novels, like L'échiquier du temps and Rêve de feu, Le sous-marin de l'espace. Novels: Le cœur de Watteau, 1944 Comme un vol de gerfauts, prix des lecteurs 1947 Belle Humeur ou la Véridique Histoire de Mandrin,1957 J'irai cracher sur vos tombes, 1959 Les Tricheurs, 1959 Jusqu'à la gauche, 1963 Les Bergères de l'Apocalypse, 1978 On vous appelait terroristes, 1979 Je ne suis pas née pour mourir, 1982 Terrorist's blues, 1987 Floralies du désert, 1995 Biographies: La vie passionnée d'Arthur Rimbaud, 1957 La vie passionnée de Verlaine, 1959 Une femme témoin de son siècle, Germaine de Staël, 1966 La couronne de sable, vie d'Isabelle Eberhardt, 1967 L'éventail de fer ou la vie de Qiu Jin, 1977 Moi, reine de Suède, 1979 L'impératrice rouge: moi, Jiang King, veuve Mao, 1981 L'Amazone Sombre: vie d'Antoinette Lix, 1983 Louise Michel la Canaque, 1985 Une femme nommée Castor, 1986 Les scandaleuses, 1990 L'évangile de Véronique, 2000 Essays: Le complexe de Diane, érotisme ou féminisme, 1951 Y a-t-il encore des hommes?, 1964 Eros minoritaire, 1970 Le féminisme ou la mort, 1974 Les femmes avant le patriarcat, 1976 Contre violence ou résistance à l'état, 1978 Histoire de l'art et lutte des sexes, 1978 Écologie, féminisme: révolution ou mutation?, 1978 S comme Sectes, 1982 La femme russe, 1988 Féminin et philosophie: une allergie historique, 1997 La liseuse et la lyre, 1997 Le sexocide des sorcières, 1999 Poems: Columns of the soul, 1942 Rutten, 1951 Neither place nor meter, 1981

List of libraries in the ancient world

The great libraries of the ancient world served as archives for empires, sanctuaries for sacred writings, depositories of literature and chronicles. Timgad The library was a gift to the Roman people and province of Thamugadi or Timgad by Julius Quintianus Flavius Rogatianus in the third century; the library contained an expansive arched hall which consisted of a reading room, stack room, a rotunda for lectures. The library was quite large measuring 81 feet in length by 77 feet in width. Oblong alcoves held wooden cabinets along walls. In addition, there is evidence for free-standing bookcases in the center as well as a reading desk. There is no evidence as to how many books the library harbored although it is estimated that it could have accommodated 3000 scrolls. Hattusa This archive constituted the largest collection of Hittite texts discovered with thirty thousand inscribed cuneiform tablets; the tablets had been classified according to a precise system. Royal Library of Antioch The library was commissioned in the third century B.

C. by Euphorion of Chalcis by the Greek sovereign Antiochus III the Great. Euphorion was an academic and was the chief librarian. Library of Pergamum The Attalid kings formed the second-best Hellenistic library after Alexandria, founded in emulation of the Ptolemies. Parchment, a predecessor of vellum and paper, was used in the library, came to be known as pergamum after the city; the library had collected over 200,000 volumes and the reason why the library was so successful was because of Pergamum's hegemony, a purveyor of scholarship. Library of Celsus This library was part of the triumvirate of libraries in the Mediterranean which included the aforementioned Library of Pergamum and the great Library of Alexandria listed below; the library was a tomb and a shrine for the deceased Tiberius Julius Celsus Polemaeanus for whom the library is named. 12,000 volumes were collected at this library which were deposited in several cabinets along the wall. The Imperial Library of Constantinople The library was established by Constantius II, the son of the first Christian emperor Constantine.

Constantius requested that the rolls of papyrus should be copied onto parchment or vellum in order that they would be preserved. It is known that several documents from the Library of Alexandria were spared incineration and secured here at the library; some assessments place the collection at just over 100,000 volumes which included papyrus scrolls and codices bound in parchment, although 120,000 volumes had been destroyed in a fire in a.d. 473. Han Imperial Library Catalogue preserved in the Yiwenzhi chapter of the Book of Han. At the time of inventory contained 596 works divided into six genres. Qin reign It was the practice of Chinese emperors to assemble and maintain their official written archive; the first Qin emperor was a determined opponent of Confucianism, worked to eradicate texts and teachings of that philosophy. Tang dynasty The Tang Dynasty is known as the Golden Age of Imperial Chinese history. Academy libraries were places where young men came to study for civil service exams, became an important part of the Chinese meritocracy.

Private collection of books was common during this time. Wood-block printing spread throughout the kingdom at this time. Social status was determined, in part, by the cultural refinement acquired through personal book collections; the Royal Library of Alexandria, Egypt, fl. 3rd century BC. Founded by Ptolemy, this library was said to have amassed an estimated 400,000 manuscripts and was considered the leading intellectual metropolis of the Hellenistic world; the Serapeum in Alexandria served as an extension of the library. Serapeum of Alexandria Offshoot collection of the great Library of Alexandria Temple of Edfu Archive/Library This library was an extension of the Temple itself; the walls of this chamber are bestrewn with engravings and captions depicting numerous receptacles filled with manuscripts of papyrus as well as scrolls bound in leather. These documents chronicled the circadian workings of the temple, but detailed construction drafts and directives on how the temple walls should be decorated.

The Library of Aksum The kingdom of Aksum, by the first century CE, was a noted trading hub for Europe and Africa. By the third century, it was the equal of the Roman and Chinese empires. Aksum had a unique written language, Ge'ez, their libraries held their own translation of the Christian Bible, other important early Christian works, it is believed. Notably, the Book of Enoch, a pre-Christian religious text, was written in Ge'ez. By the 7th century CE, the kingdom of Aksum fell due to Islamic expansion, agricultural difficulties, a trading shift away from the Red Sea in favor of the Persian Gulf, but it is remembered as a society that celebrated literacy and libraries; the Library of Aristotle The Library of Aristotle was a private library and the earliest one reported on by ancient chroniclers. It is not known the number of books that were included in the library. Accounts in antiquity state that the library formed part of the Library of Alexandria in Egypt. Kos Library The library was a local public library situated on

Mel Kiper Jr.

Melvin Adam Kiper Jr. is an American football analyst for ESPN. He has appeared on ESPN's annual NFL draft coverage since 1984, providing in-depth information on the nation's potential draft picks. Kiper said that Ernie Accorsi, general manager of the then-Baltimore Colts, encouraged him to become a draft analyst. Accorsi told him that there was a market for draft information and suggested that Kiper convert his analysis into a business. Kiper and fellow draft analyst Todd McShay are featured together and compare their mock drafts on ESPN programs. Kiper co-hosts the weekend show Mel with Dari Nowkhah on ESPN Radio. Kiper creates. During ESPN draft coverage, Kiper's big board appears on the ticker and updates automatically once a player is selected. Kiper is "unlockable" as a free agent longsnapper. Kiper appears in NFL Head Coach as a draft expert. Kiper appears in 08 during the pre-draft workout period. Kiper has been married since 1989 to Kim, who assists him in running Mel Kiper Enterprises from their Baltimore home.

They have one daughter together. Mel Kiper Jr.'s biography on ESPN.com Mel Kiper Jr.'s website

Medial graph

In the mathematical discipline of graph theory, the medial graph of plane graph G is another graph M that represents the adjacencies between edges in the faces of G. Medial graphs were introduced in 1922 by Ernst Steinitz to study combinatorial properties of convex polyhedra, although the inverse construction was used by Peter Tait in 1877 in his foundational study of knots and links. Given a connected plane graph G, its medial graph M has a vertex for each edge of G and an edge between two vertices for each face of G in which their corresponding edges occur consecutively; the medial graph of a disconnected graph is the disjoint union of the medial graphs of each connected component. The definition of medial graph extends without modification to graph embeddings on surfaces of higher genus; the medial graph of any plane graph is a 4-regular plane graph. For any plane graph G, the medial graph of G and the medial graph of the dual graph of G are isomorphic. Conversely, for any 4-regular plane graph H, the only two plane graphs with medial graph H are dual to each other.

Since the medial graph depends on a particular embedding, the medial graph of a planar graph is not unique. In the picture, the red graphs are not isomorphic because the two vertices with self loops share an edge in one graph but not in the other; every 4-regular plane graph is the medial graph of some plane graph. For a connected 4-regular plane graph H, a planar graph G with H as its medial graph can be constructed as follows. Color the faces of H with just two colors, possible since H is Eulerian; the vertices in G correspond to the faces of a single color in H. These vertices are connected by an edge for each vertex shared by their corresponding faces in H. Note that performing this construction using the faces of the other color as the vertices produces the dual graph of G; the medial graph of a 3-regular plane graph coincides with its line graph. However, this is not true for medial graphs of plane graphs that have vertices of degree greater than three. For a plane graph G, twice the evaluation of the Tutte polynomial at the point equals the sum over weighted Eulerian orientations in the medial graph of G, where the weight of an orientation is 2 to the number of saddle vertices of the orientation.

Since the Tutte polynomial is invariant under embeddings, this result shows that every medial graph has the same sum of these weighted Eulerian orientations. The medial graph definition can be extended to include an orientation. First, the faces of the medial graph are colored black if they contain a vertex of the original graph and white otherwise; this coloring causes each edge of the medial graph to be bordered by one black face and one white face. Each edge is oriented so that the black face is on its left. A plane graph and its dual do not have the same directed medial graph. Using the directed medial graph, one can generalize the result on evaluations of the Tutte polynomial at. For a plane graph G, n times the evaluation of the Tutte polynomial at the point equals the weighted sum over all edge colorings using n colors in the directed medial graph of G so that each set of monochromatic edges forms a directed Eulerian graph, where the weight of a directed Eulerian orientation is 2 to the number of monochromatic vertices.

Knots and graphs Tait graph Rectification - The equivalent operation on polyhedrons Brylawski, Thomas. "The Tutte Polynomial and Its Applications". In White, Neil. Matriod Applications. Cambridge University Press. Pp. 123–225