Ad hoc

Ad hoc

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Ad hoc is a Latin phrase meaning "for this". It generally signifies a solution designed for a specific problem or task, non-generalizable, and not intended to be able to be adapted to other purposes. Compare A priori
A priori
A priori is Latin for "from the former" or "from before", and may refer to:* A priori knowledge, justification or arguments. See a priori and a posteriori.* A priori , a type of constructed language...

.

Common examples are organizations, committees, and commissions created at the national or international level for a specific task. In other fields the term may refer, for example, to a military unit created under special circumstances, a tailor-made suit, a handcrafted network protocol, or a purpose-specific equation
Equation
An equation is a mathematical statement that asserts the equality of two expressions. In modern notation, this is written by placing the expressions on either side of an equals sign , for examplex + 3 = 5\,asserts that x+3 is equal to 5...

.

Ad hoc can also mean makeshift solutions, shifting contexts to create new meanings, inadequate planning, or improvised events.

Ad hoc committee, commission, or organization


Ad hoc organizations, including committee
Committee
A committee is a type of small deliberative assembly that is usually intended to remain subordinate to another, larger deliberative assembly—which when organized so that action on committee requires a vote by all its entitled members, is called the "Committee of the Whole"...

s and private non-profit organization
Non-profit organization
Nonprofit organization is neither a legal nor technical definition but generally refers to an organization that uses surplus revenues to achieve its goals, rather than distributing them as profit or dividends...

s, are used when an objective needs consideration and no standing organization or committee within said organization can absorb that issue into its scope. Usually these committees are used on a temporary basis, such as temporary oversight of an issue, or review of the standing rule
Standing rule
A standing rule is a rule that relates to the details of the administration of a society and which can be adopted or changed the same way as any other act of the deliberative assembly. Standing rules can be suspended by a majority vote for the duration of the session, but not for longer....

s or the constitution
Constitution
A constitution is a set of fundamental principles or established precedents according to which a state or other organization is governed. These rules together make up, i.e. constitute, what the entity is...

 of that organization.

An ad hoc organization may have, in some cases, a long-term or indefinite duration of existence. In these cases, an initial workgroup or forum may give place to a more permanent form of organization. An exaggerated typical example is the OSCE
Organization for Security and Co-operation in Europe
The Organization for Security and Co-operation in Europe is the world's largest security-oriented intergovernmental organization. Its mandate includes issues such as arms control, human rights, freedom of the press and fair elections...

.

Under the Anglo-American Cataloging Rules
AACR2
AACR2 stands for the Anglo-American Cataloguing Rules, Second Edition. It is published jointly by the American Library Association, the Canadian Library Association, and the Chartered Institute of Library and Information Professionals in the UK. The editor is Michael Gorman, a British-born...

, ad hoc events such as athletic contests, exhibitions, expeditions, fairs, and festivals are considered to be corporate bodies, and can be used as corporate body access points.

Ad hoc hypothesis


In science
Science
Science is a systematic enterprise that builds and organizes knowledge in the form of testable explanations and predictions about the universe...

 and philosophy
Philosophy
Philosophy is the study of general and fundamental problems, such as those connected with existence, knowledge, values, reason, mind, and language. Philosophy is distinguished from other ways of addressing such problems by its critical, generally systematic approach and its reliance on rational...

, ad hoc means the addition of extraneous hypotheses to a theory
Theory
The English word theory was derived from a technical term in Ancient Greek philosophy. The word theoria, , meant "a looking at, viewing, beholding", and referring to contemplation or speculation, as opposed to action...

 to save it from being falsified. Ad hoc hypotheses compensate for anomalies not anticipated by the theory in its unmodified form. Scientists are often skeptical
Scientific skepticism
Scientific skepticism is the practice of questioning the veracity of claims lacking empirical evidence or reproducibility, as part of a methodological norm pursuing "the extension of certified knowledge". For example, Robert K...

 of theories that rely on frequent, unsupported adjustments to sustain them. Ad hoc hypotheses are often characteristic of pseudoscientific subjects. Much of

Ad hoc hypotheses are not necessarily incorrect, however. An interesting example of an apparently supported ad hoc hypothesis was Albert Einstein
Albert Einstein
Albert Einstein was a German-born theoretical physicist who developed the theory of general relativity, effecting a revolution in physics. For this achievement, Einstein is often regarded as the father of modern physics and one of the most prolific intellects in human history...

's addition of the cosmological constant
Cosmological constant
In physical cosmology, the cosmological constant was proposed by Albert Einstein as a modification of his original theory of general relativity to achieve a stationary universe...

 to general relativity
General relativity
General relativity or the general theory of relativity is the geometric theory of gravitation published by Albert Einstein in 1916. It is the current description of gravitation in modern physics...

 in order to allow a static universe
Static universe
A static universe, also referred to as a "stationary" or "Einstein" universe, is a model in which space is neither expanding nor contracting. Albert Einstein proposed such a model as his preferred cosmology in 1917...

. Although he later referred to it as his "greatest blunder," it has been found to correspond quite well to the theories of dark energy
Dark energy
In physical cosmology, astronomy and celestial mechanics, dark energy is a hypothetical form of energy that permeates all of space and tends to accelerate the expansion of the universe. Dark energy is the most accepted theory to explain recent observations that the universe appears to be expanding...

.

Ad hoc querying


Ad hoc querying is a term in information science
Information science
-Introduction:Information science is an interdisciplinary science primarily concerned with the analysis, collection, classification, manipulation, storage, retrieval and dissemination of information...

.

Many application software
Application software
Application software, also known as an application or an "app", is computer software designed to help the user to perform specific tasks. Examples include enterprise software, accounting software, office suites, graphics software and media players. Many application programs deal principally with...

 systems have an underlying database which can be accessed by only a limited number of queries and reports. Typically these are available via some sort of menu, and will have been carefully designed, pre-programmed and optimized for performance by expert programmers.

By contrast, "ad hoc" reporting systems allow the users themselves to create specific, customized queries. Typically this would be via a user-friendly GUI
Gui
Gui or guee is a generic term to refer to grilled dishes in Korean cuisine. These most commonly have meat or fish as their primary ingredient, but may in some cases also comprise grilled vegetables or other vegetarian ingredients. The term derives from the verb, "gupda" in Korean, which literally...

-based system without the need for the in-depth knowledge of SQL
SQL
SQL is a programming language designed for managing data in relational database management systems ....

, or database schema
Database schema
A database schema of a database system is its structure described in a formal language supported by the database management system and refers to the organization of data to create a blueprint of how a database will be constructed...

 that a programmer would have.

Because such reporting has the potential to severely degrade the performance of a live system, it is usually provided over a data warehouse
Data warehouse
In computing, a data warehouse is a database used for reporting and analysis. The data stored in the warehouse is uploaded from the operational systems. The data may pass through an operational data store for additional operations before it is used in the DW for reporting.A data warehouse...

.

Ad hoc querying/reporting is a business intelligence
Business intelligence
Business intelligence mainly refers to computer-based techniques used in identifying, extracting, and analyzing business data, such as sales revenue by products and/or departments, or by associated costs and incomes....

 subtopic, along with OLAP
OLAP
In computing, online analytical processing, or OLAP , is an approach to swiftly answer multi-dimensional analytical queries. OLAP is part of the broader category of business intelligence, which also encompasses relational reporting and data mining...

, data warehousing, data mining
Data mining
Data mining , a relatively young and interdisciplinary field of computer science is the process of discovering new patterns from large data sets involving methods at the intersection of artificial intelligence, machine learning, statistics and database systems...

 and other tools.

Ad hoc military


In military, ad hoc units are created during unpredictable situations, when the cooperation between different units is needed for fast action. An example would be a military breakout
Breakout (military)
A breakout is a military operation to end a situation of encirclement or siege. It is used in contexts such as: "The British breakout attempt from Normandy"....

.

Ad hoc networking


The term ad hoc networking typically refers to a system of network elements that combine to form a network requiring little or no planning.
See Wireless ad hoc network.