ETL based data warehousing.

The typical extract, transform, load (ETL)-based data warehouse uses staging, data integration, and access layers to house its key functions. The staging layer or staging database stores raw data extracted from each of the disparate source data systems. The integration layer integrates the disparate data sets by transforming the data from the staging layer often storing this transformed data in an operational data store (ODS) database. The integrated data are then moved to yet another database, often called the data warehouse database, where the data is arranged into hierarchical groups, often called dimensions, and into facts and aggregate facts. The combination of facts and dimensions is sometimes called a star schema. The access layer helps users retrieve data.  The main source of the data is cleansed, transformed, catalogued, and made available for use by managers and other business professionals for data mining, online analytical processing, market research and decision support. However, the means to retrieve and analyze data, to extract, transform, and load data, and to manage the data dictionary are also considered essential components of a data warehousing system. Many references to data warehousing use this broader context. Thus, an expanded definition for data warehousing includes business intelligence tools, tools to extract, transform, and load data into the repository, and tools to manage and retrieve metadata.  IBM InfoSphere DataStage, Ab Initio Software, Informatica – PowerCenter are some of the tools which are widely used to implement ETL based data warehouse.

ELT based data warehousing.

ELT based data warehousing gets rid of a separate ETL tool for data transformation. Instead, it maintains a staging area inside the data warehouse itself. In this approach, data gets extracted from heterogeneous source systems and are then directly loaded into the data warehouse, before any transformation occurs. All necessary transformations are then handled inside the data warehouse itself. Finally, the manipulated data gets loaded into target tables in the same data warehouse.

Benefits.

A data warehouse maintains a copy of information from the source transaction systems. This architectural complexity provides the opportunity to:

Generic.

The environment for data warehouses and marts includes the following:  In regards to source systems listed above, R. Kelly Rainer states, "A common source for the data in data warehouses is the company's operational databases, which can be relational databases".  Regarding data integration, Rainer states, "It is necessary to extract data from source systems, transform them, and load them into a data mart or warehouse".  Rainer discusses storing data in an organization's data warehouse or data marts.  Metadata is data about data. "IT personnel need information about data sources; database, table, and column names; refresh schedules; and data usage measures".  Today, the most successful companies are those that can respond quickly and flexibly to market changes and opportunities. A key to this response is the effective and efficient use of data and information by analysts and managers. A "data warehouse" is a repository of historical data that is organized by subject to support decision makers in the organization. Once data is stored in a data mart or warehouse, it can be accessed.

Related systems (data mart, OLAP, OLTP, predictive analytics).

A data mart is a simple form of a data warehouse that is focused on a single subject (or functional area), hence they draw data from a limited number of sources such as sales, finance or marketing. Data marts are often built and controlled by a single department within an organization. The sources could be internal operational systems, a central data warehouse, or external data. Denormalization is the norm for data modeling techniques in this system. Given that data marts generally cover only a subset of the data contained in a data warehouse, they are often easier and faster to implement.  Types of data marts include dependent, independent, and hybrid data marts.  Online analytical processing (OLAP) is characterized by a relatively low volume of transactions. Queries are often very complex and involve aggregations. For OLAP systems, response time is an effectiveness measure. OLAP applications are widely used by Data Mining techniques. OLAP databases store aggregated, historical data in multi-dimensional schemas (usually star schemas). OLAP systems typically have data latency of a few hours, as opposed to data marts, where latency is expected to be closer to one day. The OLAP approach is used to analyze multidimensional data from multiple sources and perspectives. The three basic operations in OLAP are : Roll-up (Consolidation), Drill-down and Slicing & Dicing.  Online transaction processing (OLTP) is characterized by a large number of short on-line transactions (INSERT, UPDATE, DELETE). OLTP systems emphasize very fast query processing and maintaining data integrity in multi-access environments. For OLTP systems, effectiveness is measured by the number of transactions per second. OLTP databases contain detailed and current data. The schema used to store transactional databases is the entity model (usually 3NF). Normalization is the norm for data modeling techniques in this system.  Predictive analytics is about finding and quantifying hidden patterns in the data using complex mathematical models that can be used to predict future outcomes. Predictive analysis is different from OLAP in that OLAP focuses on historical data analysis and is reactive in nature, while predictive analysis focuses on the future. These systems are also used for customer relationship management (CRM).

History.

The concept of data warehousing dates back to the late 1980s when IBM researchers Barry Devlin and Paul Murphy developed the "business data warehouse". In essence, the data warehousing concept was intended to provide an architectural model for the flow of data from operational systems to decision support environments. The concept attempted to address the various problems associated with this flow, mainly the high costs associated with it. In the absence of a data warehousing architecture, an enormous amount of redundancy was required to support multiple decision support environments. In larger corporations, it was typical for multiple decision support environments to operate independently. Though each environment served different users, they often required much of the same stored data. The process of gathering, cleaning and integrating data from various sources, usually from long-term existing operational systems (usually referred to as legacy systems), was typically in part replicated for each environment. Moreover, the operational systems were frequently reexamined as new decision support requirements emerged. Often new requirements necessitated gathering, cleaning and integrating new data from "data marts" that was tailored for ready access by users.  Key developments in early years of data warehousing:

Information storage.

Facts.

A fact is a value, or measurement, which represents a fact about the managed entity or system.  Facts, as reported by the reporting entity, are said to be at raw level; e.g., in a mobile telephone system, if a BTS (base transceiver station) receives 1,000 requests for traffic channel allocation, allocates for 820, and rejects the remaining, it would report three facts or measurements to a management system:  Facts at the raw level are further aggregated to higher levels in various dimensions to extract more service or business-relevant information from it. These are called aggregates or summaries or aggregated facts.  For instance, if there are three BTS in a city, then the facts above can be aggregated from the BTS to the city level in the network dimension. For example:

Dimensional versus normalized approach for storage of data.

There are three or more leading approaches to storing data in a data warehouse — the most important approaches are the dimensional approach and the normalized approach.  The dimensional approach refers to Ralph Kimball's approach in which it is stated that the data warehouse should be modeled using a Dimensional Model/star schema. The normalized approach, also called the 3NF model (Third Normal Form) refers to Bill Inmon's approach in which it is stated that the data warehouse should be modeled using an E-R model/normalized model.

Dimensional approach.

In a dimensional approach, transaction data are partitioned into "facts", which are generally numeric transaction data, and "dimensions", which are the reference information that gives context to the facts. For example, a sales transaction can be broken up into facts such as the number of products ordered and the total price paid for the products, and into dimensions such as order date, customer name, product number, order ship-to and bill-to locations, and salesperson responsible for receiving the order.  A key advantage of a dimensional approach is that the data warehouse is easier for the user to understand and to use. Also, the retrieval of data from the data warehouse tends to operate very quickly. Dimensional structures are easy to understand for business users, because the structure is divided into measurements/facts and context/dimensions. Facts are related to the organization's business processes and operational system whereas the dimensions surrounding them contain context about the measurement (Kimball, Ralph 2008). Another advantage offered by dimensional model is that it does not involve a relational database every time. Thus, this type of modeling technique is very useful for end-user queries in data warehouse.  The model of facts and dimensions can also be understood as a data cube. Where the dimensions are the categorical coordinates in a multi-dimensional cube, while the fact is a value corresponding to the coordinates.  The main disadvantages of the dimensional approach are the following:

Normalized approach.

In the normalized approach, the data in the data warehouse are stored following, to a degree, database normalization rules. Tables are grouped together by "subject areas" that reflect general data categories (e.g., data on customers, products, finance, etc.). The normalized structure divides data into entities, which creates several tables in a relational database. When applied in large enterprises the result is dozens of tables that are linked together by a web of joins. Furthermore, each of the created entities is converted into separate physical tables when the database is implemented (Kimball, Ralph 2008). The main advantage of this approach is that it is straightforward to add information into the database. Some disadvantages of this approach are that, because of the number of tables involved, it can be difficult for users to join data from different sources into meaningful information and to access the information without a precise understanding of the sources of data and of the data structure of the data warehouse.  Both normalized and dimensional models can be represented in entity-relationship diagrams as both contain joined relational tables. The difference between the two models is the degree of normalization (also known as Normal Forms). These approaches are not mutually exclusive, and there are other approaches. Dimensional approaches can involve normalizing data to a degree (Kimball, Ralph 2008).  In "Information-Driven Business", Robert Hillard proposes an approach to comparing the two approaches based on the information needs of the business problem. The technique shows that normalized models hold far more information than their dimensional equivalents (even when the same fields are used in both models) but this extra information comes at the cost of usability. The technique measures information quantity in terms of information entropy and usability in terms of the Small Worlds data transformation measure.

Design methods.

Bottom-up design.

In the "bottom-up" approach, data marts are first created to provide reporting and analytical capabilities for specific business processes. These data marts can then be integrated to create a comprehensive data warehouse. The data warehouse bus architecture is primarily an implementation of "the bus", a collection of conformed dimensions and conformed facts, which are dimensions that are shared (in a specific way) between facts in two or more data marts.

Top-down design.

The "top-down" approach is designed using a normalized enterprise data model. "Atomic" data, that is, data at the greatest level of detail, are stored in the data warehouse. Dimensional data marts containing data needed for specific business processes or specific departments are created from the data warehouse.

Hybrid design.

Data warehouses (DW) often resemble the hub and spokes architecture. Legacy systems feeding the warehouse often include customer relationship management and enterprise resource planning, generating large amounts of data. To consolidate these various data models, and facilitate the extract transform load process, data warehouses often make use of an operational data store, the information from which is parsed into the actual DW. To reduce data redundancy, larger systems often store the data in a normalized way. Data marts for specific reports can then be built on top of the data warehouse.  A hybrid DW database is kept on third normal form to eliminate data redundancy. A normal relational database, however, is not efficient for business intelligence reports where dimensional modelling is prevalent. Small data marts can shop for data from the consolidated warehouse and use the filtered, specific data for the fact tables and dimensions required. The DW provides a single source of information from which the data marts can read, providing a wide range of business information. The hybrid architecture allows a DW to be replaced with a master data management repository where operational, not static information could reside.  The data vault modeling components follow hub and spokes architecture. This modeling style is a hybrid design, consisting of the best practices from both third normal form and star schema. The data vault model is not a true third normal form, and breaks some of its rules, but it is a top-down architecture with a bottom up design. The data vault model is geared to be strictly a data warehouse. It is not geared to be end-user accessible, which when built, still requires the use of a data mart or star schema based release area for business purposes.

Data warehouse characteristics.

There are basic features that define the data in the data warehouse that include subject orientation, data integration, time-variant, nonvolatile data, and data granularity.

Subject-oriented.

Unlike the operational systems, the data in the data warehouse revolves around subjects of the enterprise (database normalization). Subject orientation can be really useful for decision making. Gathering the required objects is called subject oriented.

Integrated.

The data found within the data warehouse is integrated. Since it comes from several operational systems, all inconsistencies must be removed. Consistencies include naming conventions, measurement of variables, encoding structures, physical attributes of data, and so forth.

Time-variant.

While operational systems reflect current values as they support day-to-day operations, data warehouse data represents data over a long time horizon (up to 10 years) which means it stores historical data. It is mainly meant for data mining and forecasting, If a user is searching for a buying pattern of a specific customer, the user needs to look at data on the current and past purchases.

Nonvolatile.

The data in the data warehouse is read-only which means it cannot be updated, created, or deleted.

Summarized.

In the data warehouse, data is summarized at different levels. The user may start looking at the total sale units of a product in an entire region. Then the user looks at the states in that region. Finally, they may examine the individual stores in a certain state. Therefore, typically, the analysis starts at a higher level and moves down to lower levels of details.

Data warehouse architecture.

The different methods used to construct/organize a data warehouse specified by an organization are numerous. The hardware utilized, software created and data resources specifically required for the correct functionality of a data warehouse are the main components of the data warehouse architecture. All data warehouses have multiple phases in which the requirements of the organization are modified and fine tuned.

Versus operational system.

Operational systems are optimized for preservation of data integrity and speed of recording of business transactions through use of database normalization and an entity-relationship model. Operational system designers generally follow Codd's 12 rules of database normalization to ensure data integrity. Fully normalized database designs (that is, those satisfying all Codd rules) often result in information from a business transaction being stored in dozens to hundreds of tables. Relational databases are efficient at managing the relationships between these tables. The databases have very fast insert/update performance because only a small amount of data in those tables is affected each time a transaction is processed. To improve performance, older data are usually periodically purged from operational systems.  Data warehouses are optimized for analytic access patterns. Analytic access patterns generally involve selecting specific fields and rarely if ever'select *' as is more common in operational databases. Because of these differences in access patterns, operational databases (loosely, OLTP) benefit from the use of a row-oriented DBMS whereas analytics databases (loosely, OLAP) benefit from the use of a column-oriented DBMS. Unlike operational systems which maintain a snapshot of the business, data warehouses generally maintain an infinite history which is implemented through ETL processes that periodically migrate data from the operational systems over to the data warehouse.

Evolution in organization use.

These terms refer to the level of sophistication of a data warehouse:

In computing, a data warehouse (DW or DWH), also known as an enterprise data warehouse (EDW), is a system used for reporting and data analysis, and is considered a core component of business intelligence. DWs are central repositories of integrated data from one or more disparate sources. They store current and historical data in one single place that are used for creating analytical reports for workers throughout the enterprise.

在计算机领域,数据仓库(英语:data warehouse,也称为企业数据仓库)是用于商业报告和数据分析的系统,被认为是商业智能的核心组件。 数据仓库是来自一个或多个不同源的集成数据的中央存储库。数据仓库将当前和历史数据存储在一起,用于为整个企业的员工创建分析报告。


Early life.

Richard Milhous Nixon was born on January 9, 1913, in Yorba Linda, California, in a house built by his father. His parents were Hannah (Milhous) Nixon and Francis A. Nixon. His mother was a Quaker, and his father converted from Methodism to the Quaker faith. Through his mother, Nixon was a descendant of the early English settler Thomas Cornell, who was also an ancestor of Ezra Cornell, the founder of Cornell University, as well as of Jimmy Carter and Bill Gates. Nixon's upbringing was marked by evangelical Quaker observances of the time such as refraining from alcohol, dancing, and swearing. Nixon had four brothers: Harold (1909–33), Donald (1914–87), Arthur (1918–25), and Edward (1930–2019). Four of the five Nixon boys were named after kings who had ruled in medieval or legendary Britain; Richard, for example, was named after Richard the Lionheart.  Nixon's early life was marked by hardship, and he later quoted a saying of Eisenhower to describe his boyhood: "We were poor, but the glory of it was we didn't know it". The Nixon family ranch failed in 1922, and the family moved to Whittier, California. In an area with many Quakers, Frank Nixon opened a grocery store and gas station. Richard's younger brother Arthur died in 1925 at the age of seven after a short illness. Richard was twelve years old when a spot was found on his lung. With a family history of tuberculosis, he was forbidden to play sports. Eventually, the spot was found to be scar tissue from an early bout of pneumonia.

Primary and secondary education.

Richard attended East Whittier Elementary School, where he was president of his eighth-grade class. His parents believed that attending Whittier High School had caused Richard's older brother Harold to live a dissolute lifestyle before he fell ill of tuberculosis (he died of it in 1933), so they sent Richard to the larger Fullerton Union High School. He had to ride a school bus for an hour each way during his freshman year, and received excellent grades. Later, he lived with an aunt in Fullerton during the week. He played junior varsity football, and seldom missed a practice, though he was rarely used in games. He had greater success as a debater, winning a

College and law school education.

Nixon was offered a tuition grant to attend Harvard University, but Harold's continued illness and the need for their mother to care for him meant Richard was needed at the store. He remained in his hometown and attended Whittier College with his expenses covered by a bequest from his maternal grandfather. Nixon played for the basketball team; he also tried out for football but lacked the size to play. He remained on the team as a substitute and was noted for his enthusiasm. Instead of fraternities and sororities, Whittier had literary societies. Nixon was snubbed by the only one for men, the Franklins; many of the Franklins were from prominent families, but Nixon was

Early career and marriage.

After graduating from Duke, Nixon initially hoped to join the FBI. He received no response to his letter of application and learned years later that he had been hired, but his appointment had been canceled at the last minute due to budget cuts. Instead, he returned to California and was admitted to the California bar in 1937. He began practicing in Whittier with the law firm Wingert and Bewley, working on commercial litigation for local petroleum companies and other corporate matters, as well as on wills. In later years, Nixon proudly said he was the only modern president to have previously worked as a practicing

Military service.

In January 1942 the couple moved to Washington, D.C., where Nixon took a job at the Office of Price Administration. In his political campaigns, Nixon would suggest that this was his response to Pearl Harbor, but he had sought the position throughout the latter part of 1941. Both Nixon and his wife believed he was limiting his prospects by remaining in Whittier. He was assigned to the tire rationing division, where he was tasked with replying to correspondence. He did not enjoy the role, and four months later applied to join the United States Navy. As a birthright Quaker, he could have by law claimed exemption from the draft; he might also have been deferred because he worked in government service. In spite of that, Nixon sought a commission in the Navy. His application was successful, and he was appointed a lieutenant junior grade in the U.S Naval Reserve (U.S. Navy Reserve) on June 15, 1942.  In October 1942, he was assigned as aide to the commander of the Naval Air Station Ottumwa in Iowa

Rising politician.

Congressional career.

California congressman (1947−1950).

Republicans in California's 12th congressional district were frustrated by their inability to defeat Democratic representative Jerry Voorhis, They sought a consensus candidate who would run a strong campaign against him. In 1945, they formed a "Committee of 100" to decide on a candidate, hoping to avoid internal dissensions which had led to previous Voorhis victories. After the committee failed to attract higher-profile candidates, Herman Perry, manager of Whittier's Bank of America branch, suggested Nixon, a family friend with whom he had served on the Whittier College Board of Trustees before the war. Perry wrote to Nixon in Baltimore. After a

U.S. Senate (1950−1953).

In 1949, Nixon began to consider running for the United States Senate against the Democratic incumbent, Sheridan Downey, and entered the race in November. Downey, faced with a bitter primary battle with Representative Helen Gahagan Douglas, announced his retirement in March 1950. Nixon and Douglas won the primary elections and engaged in a contentious campaign in which the ongoing Korean War was a major issue. Nixon tried to focus attention on Douglas's liberal voting record. As part of that effort, a "Pink Sheet" was distributed by the Nixon campaign suggesting that, as Douglas's voting record was

Vice presidency (1953–1961).

General Dwight D. Eisenhower was nominated for president by the Republicans in 1952. He had no strong preference for a vice presidential candidate, and Republican officeholders and party officials met in a "smoke-filled room" and recommended Nixon to the general, who agreed to the senator's selection. Nixon's youth (he was then 39), stance against communism, and political base in California—one of the largest states—were all seen as vote-winners by the leaders. Among the candidates considered along with Nixon were Ohio Senator Robert A. Taft, New Jersey Governor Alfred Driscoll and Illinois Senator Everett Dirksen. On the campaign trail, Eisenhower spoke to his plans for the country, leaving the negative campaigning to his running mate. In mid-September, the Republican ticket faced a major crisis. The media reported that Nixon had a political fund, maintained by his backers, which reimbursed him for political expenses. Such a fund was not illegal but it exposed Nixon to allegations of possible conflict of interest. With pressure building for Eisenhower to demand Nixon's resignation from the

1960 and 1962 elections; wilderness years.

In 1960 Nixon launched his first campaign for President of the United States. He faced little opposition in the Republican primaries and chose former Massachusetts Senator Henry Cabot Lodge Jr. as his running mate. His Democratic opponent was John F. Kennedy and the race remained close for the duration. Nixon campaigned on his experience but Kennedy called for new blood and claimed the Eisenhower–Nixon administration had allowed the Soviet Union to overtake the U.S. in ballistic missiles (the "missile gap").  A new political medium was introduced in the campaign: televised presidential debates. In the first of four such debates Nixon appeared pale, with a five o'clock shadow,

1968 presidential election.

At the end of 1967, Nixon told his family he planned to run for president a second time. Although Pat Nixon did not always enjoy public life (for example, she had been embarrassed by the need to reveal how little the family owned in the Checkers speech), she was supportive of her husband's ambitions. Nixon believed that with the Democrats torn over the issue of the Vietnam War, a Republican had a good chance of winning, although he expected the election to be as close as in 1960. One of the most tumultuous primary election seasons ever began as the Tet Offensive was launched in January 1968. President Johnson withdrew as a candidate in March, after doing unexpectedly poorly in the New Hampshire primary. In June, Senator Robert F. Kennedy, a Democratic candidate, was assassinated just moments after his victory in the California primary. On the Republican side, Nixon's main opposition was Michigan Governor George Romney, though New York Governor Nelson Rockefeller and California Governor Ronald Reagan each hoped to be nominated in a brokered convention. Nixon secured the nomination on the first ballot. He selected Maryland Governor Spiro Agnew as his running mate, a choice which Nixon believed would unite the party, appealing both to Northern moderates and to Southerners disaffected with the Democrats. Nixon's Democratic opponent in the general election was Vice President Hubert Humphrey, who was nominated at a convention marked by violent protests. Throughout the campaign, Nixon portrayed himself as a figure of stability during a period of national unrest and

Presidency (1969–1974).

Nixon was inaugurated as president on January 20, 1969, sworn in by his onetime political rival, Chief Justice Earl Warren. Pat Nixon held the family Bibles open at Isaiah 2:4, which reads, "They shall beat their swords into plowshares, and their spears into pruning hooks." In his inaugural address, which received almost uniformly positive reviews, Nixon remarked that "the greatest honor history can bestow is the title of peacemaker"—a phrase that would later be placed on his gravestone. He spoke about turning partisan politics into a new age of unity:

Foreign policy.

The relationship between Nixon and Henry Kissinger, his National Security Advisor was unusually close. It has been compared to the relationships of Woodrow Wilson and Colonel House, or Franklin D. Roosevelt and Harry Hopkins. In all three cases, State Department was relegated to a backseat role in developing foreign-policy. Historian David Rothkopf has compared the personalities of Nixon and Kissinger:

China.

Nixon laid the groundwork for his overture to China before he became president, writing in "Foreign Affairs" a year before his election: "There is no place on this small planet for a billion of its potentially most able people to live in angry isolation." Assisting him in this venture was Kissinger, in charge of his United States National Security Council and future Secretary of State. They collaborated closely, bypassing Cabinet officials. With relations between the Soviet Union and China at a nadir—border clashes between the two took place during Nixon's first year in office—Nixon sent private word to the Chinese that he desired closer relations. A breakthrough came in early 1971, when Chairman Mao invited a team of American table tennis players to visit China and play against top Chinese players. Nixon followed up by sending Kissinger to China for clandestine meetings with Chinese officials. On July 15, 1971, it was simultaneously announced by Beijing and by Nixon (on television and radio) that the President would visit China the following February. The announcements astounded the world. The secrecy allowed both sets of leaders time to prepare the political climate in their countries for the contact.  In February 1972, Nixon

Vietnam War.

When Nixon took office, about 300 American soldiers were dying each week in Vietnam, and the war was broadly unpopular in the United States, with ongoing violent protests against the war. The Johnson administration had agreed to suspend bombing in exchange for negotiations without preconditions, but this agreement never fully took force. According to Walter Isaacson, soon after taking office, Nixon had concluded that the Vietnam War could not be won and he was determined to end the war quickly. He sought some arrangement which would permit American forces to withdraw, while leaving South Vietnam secure

Latin American policy.

Nixon had been a firm supporter of Kennedy during the 1961 Bay of Pigs Invasion and 1962 Cuban Missile Crisis. On taking office in 1969, he stepped up covert operations against Cuba and its president, Fidel Castro. He maintained close relations with the Cuban-American exile community through his friend, Bebe Rebozo, who often suggested ways of irritating Castro. These activities concerned the Soviets and Cubans, who feared Nixon might attack Cuba and break the understanding between Kennedy and Khrushchev which had ended the missile crisis. In August 1970, the Soviets asked Nixon to reaffirm the understanding; despite his hard line against Castro, Nixon agreed. The process had not yet been completed when the

Soviet Union.

Nixon used the improving international environment to address the topic of nuclear peace. Following the announcement of his visit to China, the Nixon administration concluded negotiations for him to visit the Soviet Union. The President and First Lady arrived in Moscow on May 22, 1972, and met with Leonid Brezhnev, the General Secretary of the Communist Party; Alexei Kosygin, the Chairman of the Council of Ministers; and Nikolai Podgorny, the head of state, among other leading Soviet officials.  Nixon engaged in intense negotiations with Brezhnev. Out of the summit came agreements for increased trade and two landmark arms control treaties: SALT I, the first comprehensive limitation pact signed by the two superpowers, and the Anti-Ballistic Missile Treaty, which banned the development of systems

Middle Eastern policy.

As part of the Nixon Doctrine, the U.S. avoided giving direct combat assistance to its allies and instead gave them assistance to defend themselves. During the Nixon administration, the U.S. greatly increased arms sales to the Middle East, particularly Israel, Iran and Saudi Arabia. The Nixon administration strongly supported Israel, an American ally in the Middle East, but the support was not unconditional. Nixon believed Israel should make peace with its Arab neighbors and that the U.S. should encourage it. The president believed that—except during the Suez Crisis—the U.S. had failed to intervene with Israel, and should use the leverage of the large U.S. military aid to Israel to urge the parties to the negotiating table. The Arab-Israeli conflict was not a major focus of Nixon's attention during his first term—for one thing, he felt that no matter what he did, American Jews would oppose his reelection.  On October 6, 1973, an Arab coalition led by Egypt and Syria, supported with arms and materiel by the Soviet Union, attacked Israel in the Yom Kippur War. Israel suffered heavy losses and Nixon ordered an airlift to resupply Israeli losses, cutting through inter-departmental squabbles and bureaucracy and taking personal responsibility for any response by Arab

Domestic policy.

Economy.

At the time Nixon took office in 1969, inflation was at 4.7 percent—its highest rate since the Korean War. The Great Society had been enacted under Johnson, which, together with the Vietnam War costs, was causing large budget deficits. Unemployment was low, but interest rates were at their highest in a century. Nixon's major economic goal was to reduce inflation; the most obvious means of doing so was to end the war. This could not be accomplished overnight, and the U.S. economy continued to struggle through 1970, contributing to a lackluster Republican performance in the midterm congressional elections (Democrats controlled both Houses of Congress throughout Nixon's presidency). According to political economist Nigel Bowles in his 2011 study of Nixon's economic record, the new president did little to alter Johnson's policies through the first year of his presidency.  Nixon was far more interested in foreign affairs than domestic policies, but he believed that voters tend to focus on their own financial condition, and that economic conditions were a threat to his reelection. As part of his "New Federalism" views,

Governmental initiatives and organization.

Nixon advocated a "New Federalism", which would devolve power to state and local elected officials, though Congress was hostile to these ideas and enacted few of them. He eliminated the Cabinet-level United States Post Office Department, which in 1971 became the government-run United States Postal Service.  Nixon was a late supporter of the conservation movement. Environmental policy had not been a significant issue in the 1968 election, and the candidates were rarely asked for their views on the subject. Nixon broke new ground by discussing environmental policy in his State of the Union speech in 1970. He saw that the first Earth Day in April 1970 presaged a wave of voter interest on the subject, and sought to use that to his benefit; in June he announced the formation of the Environmental Protection Agency (EPA). He relied on his domestic advisor John Ehrlichman, who favored protection of natural resources, to keep him "out of trouble on environmental issues." Other initiatives supported by Nixon included the Clean Air

Civil rights.

The Nixon presidency witnessed the first large-scale integration of public schools in the South. Nixon sought a middle way between the segregationist Wallace and liberal Democrats, whose support of integration was alienating some Southern whites. Hopeful of doing well in the South in 1972, he sought to dispose of desegregation as a political issue before then. Soon after his inauguration, he appointed Vice President Agnew to lead a task force, which worked with local leaders—both white and black—to determine how to integrate local schools. Agnew had little interest in the work, and most of it was done by Labor Secretary George Shultz. Federal aid was available, and a meeting with President Nixon was a possible reward for compliant committees. By September 1970, less than ten percent of black children were

Space policy.

After a nearly decade-long national effort, the United States won the race to land astronauts on the Moon on July 20, 1969, with the flight of Apollo 11. Nixon spoke with Neil Armstrong and Buzz Aldrin during their moonwalk. He called the conversation "the most historic phone call ever made from the White House".  Nixon was unwilling to keep funding for the National Aeronautics and Space Administration (NASA) at the high level seen during the 1960s as NASA prepared to send men to the Moon. NASA Administrator Thomas

Reelection, Watergate scandal, and resignation.

1972 presidential campaign.

Nixon believed his rise to power had peaked at a moment of political realignment. The Democratic "Solid South" had long been a source of frustration to Republican ambitions. Goldwater had won several Southern states by opposing the Civil Rights Act of 1964 but had alienated more moderate Southerners. Nixon's efforts to gain Southern support in 1968 were diluted by Wallace's candidacy. Through his first term, he pursued a Southern Strategy with policies, such as his desegregation plans, that would be broadly acceptable among Southern whites, encouraging them to realign with the Republicans in the aftermath of the civil rights movement. He nominated two Southern conservatives, Clement Haynsworth and G. Harrold Carswell to the Supreme Court, but neither was confirmed by the Senate.  Nixon entered his name on the New Hampshire primary ballot on January 5, 1972, effectively announcing his candidacy

Watergate.

The term "Watergate" has come to encompass an array of clandestine and often illegal activities undertaken by members of the Nixon administration. Those activities included "dirty tricks," such as bugging the offices of political opponents, and the harassment of activist groups and political figures. The activities were brought to light after five men were caught breaking into the Democratic party headquarters at the Watergate complex in Washington, D.C. on June 17, 1972. "The Washington Post" picked up on the story; reporters Carl Bernstein and Bob Woodward relied on an informant known as "Deep Throat"—later revealed to be Mark Felt, associate director at the FBI—to link the men to the Nixon administration. Nixon downplayed the scandal as mere politics, calling news articles biased and misleading. A series of revelations

Resignation.

In light of his loss of political support and the near-certainty that he would be impeached and removed from office, Nixon resigned the presidency on August 9, 1974, after addressing the nation on television the previous evening. The resignation speech was delivered from the Oval Office and was carried live on radio and television. Nixon said he was resigning for the good of the country and asked the nation to support the new president, Gerald Ford. Nixon went on to review the accomplishments of his presidency, especially in foreign policy. He defended his record as president, quoting from Theodore Roosevelt's 1910 speech "Citizenship in a Republic": Nixon's speech received generally favorable initial responses from network commentators, with only Roger Mudd of CBS stating that Nixon had not admitted wrongdoing. It was termed "a masterpiece" by Conrad Black, one of his biographers. Black opined that "What was intended to be an unprecedented humiliation for any American president, Nixon converted into a virtual parliamentary acknowledgement of almost blameless insufficiency of legislative support to continue. He left while devoting half his address to a recitation of his accomplishments in office."

Post-presidency (1974–1994).

Pardon and illness.

Following his resignation, the Nixons flew to their home La Casa Pacifica in San Clemente, California. According to his biographer, Jonathan Aitken, "Nixon was a soul in torment" after his resignation. Congress had funded Nixon's transition costs, including some salary expenses, though reducing the appropriation from $850,000 to $200,000. With some of his staff still with him, Nixon was at his desk by 7:00 a.m.—with little to do. His former press secretary, Ron Ziegler, sat with him alone for hours each day.  Nixon's resignation had not put an end to the desire among many to see him punished. The Ford White House considered a pardon of Nixon, even though it would be unpopular in the country. Nixon, contacted by Ford emissaries, was initially reluctant to accept the pardon, but then agreed

Return to public life.

In December 1974, Nixon began planning his comeback despite the considerable ill will against him in the country. He wrote in his diary, referring to himself and Pat,  By early 1975, Nixon's health was improving. He maintained an office in a Coast Guard station 300 yards from his home, at first taking a golf cart and later walking the route each day; he mainly worked on his memoirs. He had hoped to wait before writing his memoirs; the fact that his assets were being eaten away by expenses and lawyer fees compelled him to begin work quickly. He was handicapped in this work by the end of his transition allowance in February, which compelled him to part with many of his staff, including Ziegler. In August of that year, he met with British talk-show host and producer David Frost, who paid him $600,000 (equivalent to $ million in ) for a series of sit-down interviews, filmed and aired in 1977. They began on the topic of foreign policy, recounting the leaders he had known, but the most remembered section of the interviews was that on Watergate. Nixon

Author and elder statesman.

In 1978, Nixon published his memoirs, "RN: The Memoirs of Richard Nixon", the first of ten books he was to author in his retirement. The book was a bestseller and attracted a generally positive critical response. Nixon visited the White House in 1979, invited by Carter for the state dinner for Chinese Vice Premier Deng Xiaoping. Carter had not wanted to invite Nixon, but Deng had said he would visit Nixon in California if the former president was not invited. Nixon had a private meeting with Deng and visited Beijing

Death and funeral.

Nixon suffered a severe stroke on April 18, 1994, while preparing to eat dinner in his Park Ridge, New Jersey home. A blood clot resulting from the atrial fibrillation he had suffered for many years had formed in his upper heart, broken off, and traveled to his brain. He was taken to New York Hospital–Cornell Medical Center in Manhattan, initially alert but unable to speak or to move his right arm or leg. Damage to the brain caused swelling (cerebral edema), and Nixon slipped into a deep coma. He died at 9:08 p.m. on April 22, 1994, with his daughters at his bedside. He was 81 years old. Nixon's funeral took place on April 27, 1994, in Yorba Linda, California. Eulogists at the Nixon Library ceremony included President Bill Clinton, former Secretary of State Henry Kissinger, Senate Minority Leader Bob Dole, California Governor Pete Wilson, and the Reverend Billy Graham. Also in attendance were former Presidents Ford, Carter, Reagan, George H. W. Bush, and their wives.  Richard Nixon was buried beside his wife Pat on the grounds of the Nixon Library. He was survived by his two daughters, Tricia and Julie, and four grandchildren. In keeping with his wishes, his funeral was not a full state funeral, though his body did lie in repose in the Nixon Library lobby from April 26 to the morning of the funeral service. Mourners waited in line for up to eight hours in chilly, wet weather to pay their respects. At its peak, the line to pass by Nixon's casket

Legacy.

Historian and political scientist James MacGregor Burns asked of Nixon, "How can one evaluate such an idiosyncratic president, so brilliant and so morally lacking?" Nixon's biographers disagree on how he will be perceived by posterity. According to Ambrose, "Nixon wanted to be judged by what he accomplished. What he will be remembered for is the nightmare he put the country through in his second term and for his resignation." Irwin Gellman, who chronicled Nixon's Congressional career, suggests, "He was remarkable among his congressional peers, a success story in a troubled era, one who steered a sensible anti-Communist course against the excess of McCarthy." Aitken feels that "Nixon, both as a man and as a statesman, has been excessively maligned for his faults and inadequately recognised for his virtues. Yet even in a spirit of historical revisionism, no simple verdict is possible."  Some historians say Nixon's Southern Strategy turned the Southern United States into a Republican stronghold, while others deem economic factors more important in the change. Throughout his career, Nixon moved his party away from the control of isolationists, and as a Congressman he was a persuasive advocate of containing Soviet communism. According to his biographer Herbert Parmet, "Nixon's role was to steer the Republican party along a middle course, somewhere between the competitive impulses of the Rockefellers, the Goldwaters, and the Reagans." Nixon's stance on domestic affairs has been credited with the passage and enforcement of environmental

Personality and public image.

Nixon's career was frequently dogged by his persona and the public's perception of it. Editorial cartoonists and comedians often exaggerated his appearance and mannerisms, to the point where the line between the human and the caricature became increasingly blurred. He was often portrayed with unshaven jowls, slumped shoulders, and a furrowed, sweaty brow. Nixon had a complex personality, both very secretive and awkward, yet strikingly reflective about himself. He was inclined to distance himself from people and was formal in all aspects, wearing a coat and tie even when home alone. Nixon biographer Conrad Black described him as being "driven" though also "uneasy with himself in some ways". According to Black, Nixon thought that he was doomed to be traduced, double-crossed, unjustly harassed, misunderstood, underappreciated, and subjected to the trials of Job, but that by the application of his mighty will, tenacity, and diligence, he would ultimately prevail. Nixon sometimes drank to excess, especially during 1970 when things were not going well for him. He also had trouble battling insomnia, for which he was prescribed sleeping pills. According to Ray Price, he sometimes took them in together. Nixon also took dilantin, recommended by Jack Dreyfus. That medicine is usually prescribed for anti-seizure attacks, but in Nixon's

External links.

Official websites  Media coverage  Other

Richard Milhous Nixon (January 9, 1913 – April 22, 1994) was the 37th president of the United States, serving from 1969 until 1974. A member of the Republican Party, Nixon previously served as the 36th vice president from 1953 to 1961, having risen to national prominence as a representative and senator from California. After five years in the White House that saw the conclusion to the U.S. involvement in the Vietnam War, détente with the Soviet Union and China, and the establishment of the Environmental Protection Agency, he became the only president to resign from the office.

理乍得·米尔豪斯·尼克松(英语:Richard Milhous Nixon,;1913年-1月9日-1994年-4月22日)是美国政治家,曾于1969年至1974年担任第37任美国总统,1974年时成为美国历史上唯一一位在任期内辞职下台的总统。尼克松曾于1953至1961年担任第36任美国副总统,还曾任加利福尼亚州联邦众议员和联邦参议员。


Great Fathers.

In both the Catholic Church and Eastern Orthodox Church traditions there are four Fathers who are called the "Great Church Fathers":  In the Catholic Church, they are also collectively called the "Eight Doctors of the Church", and in the Eastern Orthodox Church, three of them (Basil of Caesarea, Gregory of Nazianzus and John Chrysostom) are honored as the "Three Holy Hierarchs".

Apostolic Fathers.

The Apostolic Fathers were Christian theologians who lived in the 1st and 2nd centuries AD, who are believed to have personally known some of the Twelve Apostles, or to have been significantly influenced by them. Their writings, though popular in Early Christianity, were ultimately not included in the canon of the New Testament once it reached its final form. Many of the writings derive from the same time period and geographical location as other works of early Christian literature that did come to be part of the New Testament, and some of the writings found among the Apostolic Fathers' seem to have been just as highly regarded as some of the writings that became the New Testament. The first three are considered the chief ones; Clement, Ignatius and Polycarp.

Clement of Rome.

His epistle, 1 Clement (), was copied and widely read in the Early Church. Clement calls on the Christians of Corinth to maintain harmony and order. Outside of the canon of the New Testament, it is the earliest extant epistle from a Church Father.

Ignatius of Antioch.

Ignatius of Antioch (also known as Theophorus) ( – ) was the third bishop or Patriarch of Antioch and a student of the Apostle John. En route to his martyrdom in Rome, Ignatius wrote a series of letters which have been preserved. Important topics addressed in these letters include ecclesiology, the sacraments, the role of bishops, and the Incarnation of Christ. He is the second after Clement to mention Paul's epistles.

Polycarp of Smyrna.

Polycarp of Smyrna ( – ) was a Christian bishop of Smyrna (now İzmir in Turkey). It is recorded that he had been a disciple of "John". The options/possibilities for this John are John, the son of Zebedee, traditionally viewed as the author of the Gospel of John, or John the Presbyter. Traditional advocates follow Eusebius of Caesarea in insisting that the apostolic connection of Polycarp was with John the Evangelist, and that he was the author of the Gospel of John, and thus the Apostle John.  Polycarp tried and failed to persuade Pope Anicetus to have the West celebrate Passover on the 14th of Nisan, as in the Eastern calendar. Around A.D. 155, the Smyrnans of his town demanded Polycarp's execution as a Christian, and he died a martyr. The story of his martyrdom describes how the fire built around him would not burn him, and that when he was stabbed to death, so much blood issued from his body that it quenched the flames around him. Polycarp is recognized as a saint in both the Roman Catholic and Eastern Orthodox churches.

Papias of Hierapolis.

Very little is known of Papias apart from what can be inferred from his own writings. He is described as "an ancient man who was a hearer of John and a companion of Polycarp" by Polycarp's disciple Irenaeus (). Eusebius adds that Papias was Bishop of Hierapolis around the time of Ignatius of Antioch. In this office Papias was presumably succeeded by Abercius of Hierapolis. The name Papias was very common in the region, suggesting that he was probably a native of the area. The work of Papias is dated by most modern scholars to about A.D. 95–120.  Despite indications that the work of Papias was still extant in the Late Middle Ages, the full text is now lost. Extracts, however, appear in a number of other writings, some of which cite a book number.

Greek Fathers.

Those who wrote in Greek are called the Greek (Church) Fathers. In addition to the Apostolic Fathers, famous Greek Fathers include: Justin Martyr, Irenaeus of Lyons, Clement of Alexandria, Athanasius of Alexandria, John Chrysostom, Cyril of Alexandria, the Cappadocian Fathers (Basil of Caesarea, Gregory Nazianzus, Gregory of Nyssa), Peter of Sebaste, Maximus the Confessor, and John of Damascus.

Justin Martyr.

Justin Martyr was an early Christian apologist, and is regarded as the foremost interpreter of the theory of the Logos in the 2nd century. He was martyred, alongside some of his students, and is considered a saint by the Roman Catholic Church, the Anglican Church, the Eastern Orthodox Church, and the Oriental Orthodox Churches.

Irenaeus of Lyons.

Irenaeus was bishop of Lugdunum in Gaul, which is now Lyon(s), France. His writings were formative in the early development of Christian theology, and he is recognized as a saint by both the Eastern Orthodox Church and the Roman Catholic Church. He was a notable early Christian apologist. He was also a disciple of Polycarp.  His best-known book, "Against Heresies" (c.180) enumerated heresies and attacked them. Irenaeus wrote that the only way for Christians to retain unity was to humbly accept one doctrinal authority—episcopal councils. Irenaeus proposed that the Gospels of Matthew, Mark, Luke and John all be accepted as canonical.

Clement of Alexandria.

Clement of Alexandria was the first member of the church of Alexandria to be more than a name, and one of its most distinguished teachers. He united Greek philosophical traditions with Christian doctrine and valued "gnosis" that with communion for all people could be held by common Christians. He developed a Christian Platonism. Like Origen, he arose from Catechetical School of Alexandria and was well versed in pagan literature.

Origen of Alexandria.

Origen, or Origen Adamantius ( – ) was a scholar and theologian. According to tradition, he was an Egyptian who taught in Alexandria, reviving the Catechetical School where Clement had taught. The patriarch of Alexandria at first supported Origen but later expelled him for being ordained without the patriarch's permission. He relocated to Caesarea Maritima and died there after being tortured during a persecution. He was later anathematised and some of his writings condemned as heretical. Using his knowledge of Hebrew, he produced a corrected Septuagint. He wrote commentaries on all the books of the Bible. In "Peri Archon" ("First Principles"), he articulated the first philosophical exposition of Christian doctrine. He interpreted scripture allegorically and showed himself to be a stoic, a Neo-Pythagorean, and a Platonist. Like Plotinus, he wrote that the soul passes through successive stages before incarnation as a human and after death, eventually reaching God. He imagined even demons being reunited with God. For Origen, God was not Yahweh but the First Principle, and Christ, the Logos, was subordinate to him. His views of a hierarchical structure in the Trinity, the temporality of matter, "the fabulous preexistence of souls", and "the monstrous restoration which follows from it" were declared anathema in the 6th century. Prior to this, he was not considered heretical.

Athanasius of Alexandria.

Athanasius of Alexandria ( – 373) was a theologian, Pope of Alexandria, and a noted Egyptian leader of the 4th century. He is remembered for his role in the conflict with Arianism and for his affirmation of the Trinity. At the First Council of Nicaea (325), Athanasius argued against the Arian doctrine that Christ is of a distinct substance from the Father.

Cappadocian Fathers.

The Cappadocian Fathers are Basil the Great (330–379), who was bishop of Caesarea; Basil's younger brother Gregory of Nyssa ( – 395), who was bishop of Nyssa; and a close friend, Gregory of Nazianzus (329–389), who became Patriarch of Constantinople. The Cappadocians promoted early Christian theology and are highly respected in both Western and Eastern churches as saints. They were a 4th-century monastic family, led by Macrina the Younger (324–379) to provide a central place for her brothers to study and meditate, and also to provide a peaceful shelter for their mother. Abbess Macrina fostered the education and development of her three brothers Basil the Great, Gregory of Nyssa and Peter of Sebaste ( – 391) who became bishop of Sebaste.  These scholars set out to demonstrate that Christians could hold their own in conversations with learned Greek-speaking intellectuals. They argued that Christian faith, while it was against many of the ideas of Plato and Aristotle (and other Greek philosophers), was an almost scientific and distinctive movement with the healing of the soul of man and his union with God at its center. They made major contributions to the definition of the Trinity finalized at the First Council of Constantinople in 381 and the final version of the Nicene Creed.  Subsequent to the First Council of Nicea, Arianism did not simply disappear. The semi-Arians taught that the Son is of like substance with the Father (homoiousios), as against the outright Arians who taught that the Son was unlike the Father (heterousian). So the Son was held to be "like" the Father but not of the same essence as the Father. The Cappadocians worked to bring these semi-Arians back to the Orthodox cause. In their writings they made extensive use of the formula "three substances (hypostases) in one essence (homoousia)", and thus explicitly acknowledged a distinction between the Father and the Son (a distinction that Nicea had been accused of blurring) but at the same time insisting on their essential unity.

John Chrysostom.

John Chrysostom ( – ), archbishop of Constantinople, is known for his eloquence in preaching and public speaking; his denunciation of abuse of authority by both ecclesiastical and political leaders, recorded sermons and writings making him the most prolific of the eastern fathers, and his ascetic sensibilities. After his death (or according to some sources, during his life) he was given the Greek epithet "chrysostomos", meaning "golden mouthed", rendered in English as Chrysostom.  Chrysostom is known within Christianity chiefly as a preacher and theologian, particularly in the Eastern Orthodox Church; he is the patron saint of orators in the Roman Catholic Church. Chrysostom is also noted for eight of his sermons that played a considerable part in the history of Christian antisemitism, diatribes against Judaizers composed while a presbyter in Antioch, which were extensively exploited and misused by the Nazis in their ideological campaign against the Jews.. Patristic scholars such as Robert L Wilken point out that applying modern understandings of antisemitism back to Chrysostom is anachronistic due to his use of the Psogos. The Psogos, along with the encomium, were both rhetorical techniques used in the ancient world in a polemical context. With the encomium "one passes over a man's faults in order to praise him, and in a psogos, one passed over his virtues to defame him. Such principles are explicit in the handbooks of the rhetors, but an interesting passage from the church historian Socrates, writing in the mid-fifth century, shows that the rules for invective were simply taken for granted by men and women of the late Roman world"  Chrysostom's sermons along with Basil the Great's have greatly influenced the Christian Church's understanding of economic and distributive justice for the poor, being cited extensively by the Catechism of the Catholic Church as well as Pope Francis in his own sermons critiquing modern-day forms of capitalism

Cyril of Alexandria.

Cyril of Alexandria ( – 444) was the Bishop of Alexandria when the city was at its height of influence and power within the Roman Empire. Cyril wrote extensively and was a leading protagonist in the Christological controversies of the late 4th and early 5th centuries. He was a central figure in the First Council of Ephesus in 431, which led to the deposition of Nestorius as Archbishop of Constantinople. Cyril's reputation within the Christian world has resulted in his titles "Pillar of Faith" and "Seal of all the Fathers".

Maximus the Confessor.

Maximus the Confessor (also known as Maximus the Theologian and Maximus of Constantinople) ( – 662) was a Christian monk, theologian, and scholar. In his early life, he was a civil servant and an aide to the Byzantine Emperor Heraclius. However, he gave up this life in the political sphere to enter into the monastic life.  After moving to Carthage, Maximus studied several Neo-Platonist writers and became a prominent author. When one of his friends began espousing the Christological position known as Monothelitism, Maximus was drawn into the controversy, in which he supported the Chalcedonian position that Jesus had both a human and a divine will. Maximus is venerated in both Eastern Christianity and Western Christianity. His Christological positions eventually resulted in his torture and exile, soon after which he died. However, his theology was vindicated by the Third Council of Constantinople, and he was venerated as a saint soon after his death. His feast day is celebrated twice during the year: on 21 January and on 13 August. His title of Confessor means that he suffered for the faith, but not to the point of death, and thus is distinguished from a martyr. His "Life of the Virgin" is thought to be the earliest complete biography of Mary, the mother of Jesus.

John of Damascus.

John of Damascus ( – 749) was a Syrian Christian monk and priest. Born and raised in Damascus, he died at his monastery, Mar Saba, near Jerusalem.  A polymath whose fields of interest and contribution included law, theology, philosophy, and music, before being ordained, he served as a chief administrator to the Muslim caliph of Damascus, wrote works expounding the Christian faith, and composed hymns which are still in use in Eastern Christian monasteries. The Catholic Church regards him as a Doctor of the Church, often referred to as the Doctor of the Assumption because of his writings on the Assumption of Mary.

Latin Fathers.

Those fathers who wrote in Latin are called the Latin (Church) Fathers.

Tertullian.

Quintus Septimius Florens Tertullianus ( – ), who was converted to Christianity before 197, was a prolific writer of apologetic, theological, controversial and ascetic works. He was born in Carthage, the son of a Roman centurion.  Tertullian denounced Christian doctrines he considered heretical, but later in life adopted Montanism, regarded as heretical by the mainstream Church, which prevented his canonization. He wrote three books in Greek and was the first great writer of Latin Christianity, thus sometimes known as the "Father of the Latin Church". He was evidently a lawyer in Rome. He is said to have introduced the Latin term "trinitas" with regard to the Divine (Trinity) to the Christian vocabulary (but Theophilus of Antioch already wrote of "the Trinity, of God, and His Word, and His wisdom", which is similar but not identical to the Trinitarian wording), and also probably the formula "three Persons, one Substance" as the Latin ""tres Personae, una Substantia"" (itself from the Koine Greek "τρεῖς ὑποστάσεις, ὁμοούσιος; "treis Hypostases, Homoousios""), and also the terms "vetus testamentum" (Old Testament) and "novum testamentum" (New Testament).  In his "Apologeticus", he was the first Latin author who qualified Christianity as the "vera religio", and systematically relegated the classical Roman Empire religion and other accepted cults to the position of mere "superstitions".  Later in life, Tertullian joined the Montanists, a heretical sect that appealed to his rigorism. He used the early church's symbol for fish—the Greek word for "fish" being ΙΧΘΥΣ which is an acronym for Ιησοῦς Χριστός, Θεοῦ Υἱός, Σωτήρ (Jesus Christ, God's Son, Saviour)—to explain the meaning of baptism since fish are born in water. He wrote that human beings are like little fish.

Cyprian of Carthage.

Cyprian ( – 258) was bishop of Carthage and an important early Christian writer. He was born in North Africa, probably at the beginning of the 3rd century, perhaps at Carthage, where he received an excellent classical (pagan) education. After converting to Christianity, he became a bishop and eventually died a martyr at Carthage. He emphasized the necessity of the unity of Christians with their bishops, and also the authority of the Roman See, which he claimed was the source of "priestly unity"'.

Hilary of Poitiers.

Hilary of Poitiers ( – ) was Bishop of Poitiers and is a Doctor of the Church. He was sometimes referred to as the "Hammer of the Arians" () and the "Athanasius of the West"/ His name comes from the Latin word for happy or cheerful. His optional memorial in the Roman Catholic calendar of saints is 13 January. In the past, when this date was occupied by the Octave Day of the Epiphany, his feast day was moved to 14 January.

Ambrose of Milan.

Ambrose was an archbishop of Milan who became one of the most influential ecclesiastical figures of the 4th century. He was a Governor before becoming bishop.He is counted as one of the four original doctors of the Church. He offered a new perspective on the theory of atonement.

Pope Damasus I.

Pope Damasus I (305–384) was active in defending the Catholic Church against the threat of schisms. In two Roman synods (368 and 369) he condemned the heresies of Apollinarianism and Macedonianism, and sent legates (papal representatives) to the First Council of Constantinople that was convoked in 381 to address these heresies. He also wrote in defense of the Roman See's authority, and inaugurated use of Latin in the Mass, instead of the Koine Greek that was still being used throughout the Church in the west in the liturgy.

Jerome of Stridonium.

Jerome ( – 420) is best known as the translator of the Bible from Greek and Hebrew into Latin. He also was a Christian apologist. Jerome's edition of the Bible, the "Vulgate", is still an important text of Catholicism. He is recognised by the Roman Catholic Church as a Doctor of the Church.

Augustine of Hippo.

Augustine (354–430), Bishop of Hippo, was a philosopher and theologian. Augustine, a Latin Father and Doctor of the Church, is one of the most important figures in the development of Western Christianity. In his early life, Augustine read widely in Greco-Roman rhetoric and philosophy, including the works of Platonists such as Plotinus. He framed the concepts of original sin and just war as they are understood in the West. When Rome fell and the faith of many Christians was shaken, Augustine wrote "The City of God", in which he defended Christianity from pagan critics and developed the concept of the Church as a spiritual City of God, distinct from the material City of Man. Augustine's work defined the start of the medieval worldview, an outlook that would later be firmly established by Pope Gregory the Great.  Augustine was born in present-day Algeria to a Christian mother, Monica of Hippo. He was educated in North Africa and resisted his mother's pleas to become Christian. He took a concubine and became a Manichean. He later converted to Christianity, became a bishop, and opposed heresies, such as Pelagianism. His many works—including "The Confessions", which is often called the first Western autobiography—have been read continuously since his lifetime. The Roman Catholic religious order, the Order of Saint Augustine, adopted his name and way of life. Augustine is also the patron saint of many institutions and a number have been named after him.

Pope Gregory the Great.

Gregory I the Great ( – 604) was pope from 3 September 590 until his death. He is also known as Gregorius Dialogus ("Gregory the Dialogist") in Eastern Orthodoxy because of the "Dialogues" he wrote. He was the first of the popes from a monastic background. Gregory is a Doctor of the Church and one of the four great Latin Fathers of the Church (the others being Ambrose, Augustine, and Jerome). Of all popes, Gregory I had the most influence on the early medieval church.

Isidore of Seville.

Isidore of Seville ( – 636) was Archbishop of Seville for more than three decades and is considered, as the historian Montalembert put it in an oft-quoted phrase, "le dernier savant du monde ancien" ("the last scholar of the ancient world"). Indeed, all the later medieval history-writing of Hispania (the Iberian Peninsula, comprising modern Spain and Portugal) was based on his histories.  At a time of disintegration of classical culture and aristocratic violence and illiteracy, he was involved in the conversion of the royal Visigothic Arians to Catholicism, both assisting his brother Leander of Seville and continuing after his brother's death. He was influential in the inner circle of Sisebut, Visigothic king of Hispania. Like Leander, he played a prominent role in the Councils of Toledo and Seville. The Visigothic legislation which resulted from these councils is regarded by modern historians as exercising an important influence on the beginnings of representative government.

Syriac Fathers.

A few Church Fathers wrote in Syriac; many of their works were also widely translated into Latin and Greek.

Aphrahat.

Aphrahat (c. 270–c. 345) was a Syriac-Christian author of the 3rd century from the Adiabene region of Northern Mesopotamia, which was within the Persian Empire, who composed a series of twenty-three expositions or homilies on points of Christian doctrine and practice. He was born in Persia around 270, but all his known works, the "Demonstrations", come from later on in his life. He was an ascetic and celibate, and was almost definitely a son of the covenant (an early Syriac form of communal monasticism). He may have been a bishop, and later Syriac tradition places him at the head of Mar Matti monastery near Mosul, in what is now northern Iraq. He was a near contemporary to the slightly younger Ephrem the Syrian, but the latter lived within the sphere of the Roman Empire. Called the "Persian Sage" (, ḥakkîmâ p̄ārsāyā), Aphrahat witnesses to the concerns of the early church beyond the eastern boundaries of the Roman Empire.

Ephrem the Syrian.

Ephrem the Syrian (ca. 306 – 373) was a Syriac deacon and a prolific Syriac-language hymnographer and theologian of the 4th century from the region of Syria. His works are hailed by Christians throughout the world, and many denominations venerate him as a saint. He has been declared a Doctor of the Church in Roman Catholicism. He is especially beloved in the Syriac Orthodox Church.  Ephrem wrote a wide variety of hymns, poems, and sermons in verse, as well as prose biblical exegesis. These were works of practical theology for the edification of the church in troubled times. So popular were his works, that, for centuries after his death, Christian authors wrote hundreds of pseudepigraphal works in his name. He has been called the most significant of all of the fathers of the Syriac-speaking church tradition.

Isaac of Antioch.

Isaac of Antioch (451–452), one of the stars of Syriac literature, is the reputed author of a large number of metrical homilies (The fullest list, by Gustav Bickell, contains 191 which are extant in MSS), many of which are distinguished by an originality and acumen rare among Syriac writers.

Isaac of Nineveh.

Isaac of Nineveh was a 7th-century Syriac bishop and theologian best remembered for his written work. He is also regarded as a saint in the Church of the East, the Catholic Church, the Eastern Orthodox Church and among the Oriental Orthodox Churches, making him the last saint chronologically to be recognised by every apostolic Church. His feast day falls on January 28 and in the Syriac Orthodox calendar on March 14. Isaac is remembered for his spiritual homilies on the inner life, which have a human breadth and theological depth that transcends the Nestorian Christianity of the Church to which he belonged. They survive in Syriac manuscripts and in Greek and Arabic translations.

Desert Fathers.

The Desert Fathers were early monastics living in the Egyptian desert; although they did not write as much, their influence was also great. Among them are Paul of Thebes, Anthony the Great and Pachomius. Many of their, usually short, sayings are collected in the "Apophthegmata Patrum" ("Sayings of the Desert Fathers").

Modern positions.

In the Catholic Church, John of Damascus, who lived in the 8th century, is generally considered to be a Doctor of the Church and at the same time the first seed of the next period of church writers, scholasticism. The Eastern Orthodox Church does not consider the age of Church Fathers to be over and includes later influential writers up to the present day. The Orthodox view is that men do not have to agree on every detail, much less be infallible, to be considered Church Fathers. Rather, Orthodox doctrine is determined by the consensus of the Holy Fathers—those points on which they do agree. This consensus guides the church in questions of dogma, the correct interpretation of scripture, and to distinguish the authentic sacred tradition of the Church from false teachings.  The original Lutheran "Augsburg Confession" of 1530, for example, and the later "Formula of Concord" of 1576–1584, each begin with the mention of the doctrine professed by the Fathers of the First Council of Nicaea.  Though much Protestant religious thought is based on "sola scriptura" (the principle that the Bible itself is the ultimate authority in doctrinal matters), the first Protestant reformers, like the Catholic and Orthodox churches, used the theological interpretations of scripture set forth by the early Church Fathers. John Calvin's "French Confession of Faith" of 1559 states, "And we confess that which has been established by the ancient councils, and we detest all sects and heresies which were rejected by the holy doctors, such as St. Hilary, St. Athanasius, St. Ambrose and St. Cyril." The "Scots Confession" of 1560 deals with general councils in its 20th chapter. The Thirty-nine Articles of the Church of England, both the original of 1562-1571 and the American version of 1801, explicitly accept the Nicene Creed in Article VII. Even when a particular Protestant confessional formula does not mention the Nicene Council or its creed, its doctrine is nonetheless always asserted, as, for example, in the Presbyterian "Westminster Confession" of 1647. Many Protestant seminaries provide courses on patristics as part of their curriculum, and many historic Protestant churches emphasize the importance of tradition and of the fathers in scriptural interpretation. Such an emphasis is even more pronounced in certain streams of Protestant thought, such as Paleo-Orthodoxy.

Patristics.

The study of the Church Fathers is known as "patristics".  Works of fathers in early Christianity, prior to Nicene Christianity, were translated into English in a 19th-century collection "Ante-Nicene Fathers". Those of the First Council of Nicaea and continuing through the Second Council of Nicea (787) are collected in "Nicene and Post-Nicene Fathers."

The Church Fathers, Early Church Fathers, Christian Fathers, or Fathers of the Church were ancient and influential Christian theologians and writers who established the intellectual and doctrinal foundations of Christianity. There is no definitive list. The historical period during which they flourished is referred to by scholars as the Patristic Era ending approximately around AD 700 (John of Damascus died in 749 AD, Byzantine Iconoclasm began in 726 AD).

教父(英语:Church Fathers,或 英语:Fathers of the church),又译为天主教早期教父(英语:Early Church Fathers),是天主教会(基督教)早期宗教作家及宣教师的统称。他们的著作被认定具备权威,可以作为教会的教义指引与先例。他们包括许多著名的教会神学家、主教和护教士,但是不一定是教会认定的圣人,有些教父甚至被教会判定为“异端”。


Operations.

In an associative array, the association between a key and a value is often known as a "mapping", and the same word mapping may also be used to refer to the process of creating a new association.  The operations that are usually defined for an associative array are:  Often then instead of add or reassign there is a single set operation that adds a new formula_1 pair if one does not already exist, and otherwise reassigns it.  In addition, associative arrays may also include other operations such as determining the number of mappings or constructing an iterator to loop over all the mappings. Usually, for such an operation, the order in which the mappings are returned may be implementation-defined.  A multimap generalizes an associative array by allowing multiple values to be associated with a single key. A bidirectional map is a related abstract data type in which the mappings operate in both directions: each value must be associated with a unique key, and a second lookup operation takes a value as an argument and looks up the key associated with that value.

Example.

Suppose that the set of loans made by a library is represented in a data structure. Each book in a library may be checked out only by a single library patron at a time. However, a single patron may be able to check out multiple books. Therefore, the information about which books are checked out to which patrons may be represented by an associative array, in which the books are the keys and the patrons are the values. Using notation from Python or JSON, the data structure would be:  A lookup operation on the key "Great Expectations" would return "John". If John returns his book, that would cause a deletion operation, and if Pat checks out a book, that would cause an insertion operation, leading to a different state:

Implementation.

For dictionaries with very small numbers of mappings, it may make sense to implement the dictionary using an association list, a linked list of mappings. With this implementation, the time to perform the basic dictionary operations is linear in the total number of mappings; however, it is easy to implement and the constant factors in its running time are small.  Another very simple implementation technique, usable when the keys are restricted to a narrow range, is direct addressing into an array: the value for a given key "k" is stored at the array cell "A"["k"], or if there is no mapping for "k" then the cell stores a special sentinel value that indicates the absence of a mapping. As well as being simple, this technique is fast: each dictionary operation takes constant time. However, the space requirement for this structure is the size of the entire keyspace, making it impractical unless the keyspace is small.  The two major approaches to implementing dictionaries are a hash table or a search tree.

Hash table implementations.

The most frequently used general purpose implementation of an associative array is with a hash table: an array combined with a hash function that separates each key into a separate "bucket" of the array. The basic idea behind a hash table is that accessing an element of an array via its index is a simple, constant-time operation. Therefore, the average overhead of an operation for a hash table is only the computation of the key's hash, combined with accessing the corresponding bucket within the array. As such, hash tables usually perform in O(1) time, and outperform alternatives in most situations.  Hash tables need to be able to handle collisions: when the hash function maps two different keys to the same bucket of the array. The two most widespread approaches to this problem are separate chaining and open addressing. In separate chaining, the array does not store the value itself but stores a pointer to another container, usually an association list, that stores all of the values matching the hash. On the other hand, in open addressing, if a hash collision is found, then the table seeks an empty spot in an array to store the value in a deterministic manner, usually by looking at the next immediate position in the array.  Open addressing has a lower cache miss ratio than separate chaining when the table is mostly empty. However, as the table becomes filled with more elements, open addressing's performance degrades exponentially. Additionally, separate chaining uses less memory in most cases, unless the entries are very small (less than four times the size of a pointer).

Tree implementations.

Self-balancing binary search trees.

Another common approach is to implement an associative array with a self-balancing binary search tree, such as an AVL tree or a red-black tree.  Compared to hash tables, these structures have both advantages and weaknesses. The worst-case performance of self-balancing binary search trees is significantly better than that of a hash table, with a time complexity in big O notation of O(log "n"). This is in contrast to hash tables, whose worst-case performance involves all elements sharing a single bucket, resulting in O("n") time complexity. In addition, and like all binary search trees, self-balancing binary search trees keep their elements in order. Thus, traversing its elements follows a least-to-greatest pattern, whereas traversing a hash table can result in elements being in seemingly random order. However, hash tables have a much better average-case time complexity than self-balancing binary search trees of O(1), and their worst-case performance is highly unlikely when a good hash function is used.  It is worth noting that a self-balancing binary search tree can be used to implement the buckets for a hash table that uses separate chaining. This allows for average-case constant lookup, but assures a worst-case performance of O(log "n"). However, this introduces extra complexity into the implementation, and may cause even worse performance for smaller hash tables, where the time spent inserting into and balancing the tree is greater than the time needed to perform a linear search on all of the elements of a linked list or similar data structure.

Other trees.

Associative arrays may also be stored in unbalanced binary search trees or in data structures specialized to a particular type of keys such as radix trees, tries, Judy arrays, or van Emde Boas trees, though the ability of these implementation methods within comparison to hash tables varies; for instance, Judy trees remain indicated to perform with a smaller quantity of efficiency than hash tables, while carefully selected hash tables generally perform with increased efficiency in comparison to adaptive radix trees, with potentially greater restrictions on the types of data that they can handle. The advantages of these alternative structures come from their ability to handle operations beyond the basic ones of an associative array, such as finding the mapping whose key is the closest to a queried key, when the query is not itself present in the set of mappings.

Ordered dictionary.

The basic definition of the dictionary does not mandate an order. To guarantee a fixed order of enumeration, ordered versions of the associative array are often used. There are two senses of an ordered dictionary:  The latter sense of ordered dictionaries are more commonly encountered. They can be implemented using an association list, or by overlaying a doubly linked list on top of a normal dictionary. The latter approach, as used by CPython before version 3.6, has the advantage of keeping the potentially better complexity of another implementation. CPython 3.6+ makes dictionaries ordered by splitting the hash table into an insertion-ordered array and a sparse array ("hash table") of indices.

Language support.

Associative arrays can be implemented in any programming language as a package and many language systems provide them as part of their standard library. In some languages, they are not only built into the standard system, but have special syntax, often using array-like subscripting.  Built-in syntactic support for associative arrays was introduced in 1969 by SNOBOL4, under the name "table". TMG offered tables with string keys and integer values. MUMPS made multi-dimensional associative arrays, optionally persistent, its key data structure. SETL supported them as one possible implementation of sets and maps. Most modern scripting languages, starting with AWK and including Rexx, Perl, Tcl, JavaScript, Maple, Python, Ruby, Wolfram Language, Go, and Lua, support associative arrays as a primary container type. In many more languages, they are available as library functions without special syntax.  In Smalltalk, Objective-C,.NET, Python, REALbasic, Swift, VBA and Delphi they are called "dictionaries"; in Perl, Ruby and Seed7 they are called "hashes"; in C++, Java, Go, Clojure, Scala, OCaml, Haskell they are called "maps" (see map (C++), unordered_map (C++), and ); in Common Lisp and Windows PowerShell, they are called "hash tables" (since both typically use this implementation); in Maple and Lua, they are called "tables". In PHP, all arrays can be associative, except that the keys are limited to integers and strings. In JavaScript (see also JSON), all objects behave as associative arrays with string-valued keys, while the Map and WeakMap types take arbitrary objects as keys. In Lua, they are used as the primitive building block for all data structures. In Visual FoxPro, they are called "Collections". The D language also has support for associative arrays.

Permanent storage.

Many programs using associative arrays will at some point need to store that data in a more permanent form, like in a computer file. A common solution to this problem is a generalized concept known as "archiving" or "serialization", which produces a text or binary representation of the original objects that can be written directly to a file. This is most commonly implemented in the underlying object model, like.Net or Cocoa, which include standard functions that convert the internal data into text form. The program can create a complete text representation of any group of objects by calling these methods, which are almost always already implemented in the base associative array class.  For programs that use very large data sets, this sort of individual file storage is not appropriate, and a database management system (DB) is required. Some DB systems natively store associative arrays by serializing the data and then storing that serialized data and the key. Individual arrays can then be loaded or saved from the database using the key to refer to them. These key-value stores have been used for many years and have a history as long as that as the more common relational database (RDBs), but a lack of standardization, among other reasons, limited their use to certain niche roles. RDBs were used for these roles in most cases, although saving objects to a RDB can be complicated, a problem known as object-relational impedance mismatch.  After, the need for high performance databases suitable for cloud computing and more closely matching the internal structure of the programs using them led to a renaissance in the key-value store market. These systems can store and retrieve associative arrays in a native fashion, which can greatly improve performance in common web-related workflows.

In computer science, an associative array, map, symbol table, or dictionary is an abstract data type composed of a collection of (key, value) pairs, such that each possible key appears at most once in the collection.

在计算机科学中,关联数组(),又称映射()、字典()是一个抽象的数据结构,它包含着类似于(键,值)的有序对。一个关联数组中的有序对可以重复(如C++中的multimap)也可以不重复(如C++中的map)。