Ad hoc
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Ad hoc is a Latin phrase which means "for this [purpose]". It generally signifies a solution that has been custom designed for a specific problem or task, is non-generalizable, and cannot be adapted to other purposes. Common examples are organizations, committees and commissions created at national or international level for a specific task, or in other fields the term may refer for example to a tailor-made suit, a handcrafted network protocol or a purpose-specific equation. Ad hoc can also have connotations of a makeshift solution, inadequate planning, or improvised events. Other derivates of the Latin include AdHoc, adhoc and ad-hoc.
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[edit] Ad hoc committee, commission or organization
One which is formed to deal with a particular issue, and will be disbanded after the issue is resolved. These committees and commissions provide stop gap or temporary measures to solve problems that are not resolved by ordinary processes of the organization to which the committee belongs. The GATT, for example, was controlled by an ad-hoc committee before the WTO was established.
[edit] Ad hoc computer network
Ad hoc is a network connection method which is most often associated with wireless devices. The connection is established for the duration of one session and requires no base station. Instead, devices discover others within range to form a network for those computers. Devices may search for target nodes that are out of range by flooding the network with broadcasts that are forwarded by each node. Connections are possible over multiple nodes (multihop ad hoc network). Routing protocols then provide stable connections even if nodes are moving around. Sony's PlayStation Portable uses ad hoc connections for wireless multiplayer gaming, as does the Nintendo DS (although Nintendo does not officially use the term). Technically, the Nintendo Game Boy used this method for linking up to each other in a wired (Game Link Cable) or wireless (Game Boy Color IR Port, Game Boy Advance Wireless Adapter) mode.
See IEEE 802.11, Bluetooth, or ultra-wide band. The alternative is infrastructure, with a base station that manages the network for its range. The theory behind ad hoc networks falls within the Distributed Transient Network-paradigm.
The term ad hoc network can also refer to an independent basic service set (IBSS).
[edit] Mobile Ad Hoc and Social Network
Mobile ad hoc social network describe the new social networks constructed by the combination of computation, communication, reputation, and location awareness. More precisely, p2p computing and wireless networking technologies make it possible to design ad hoc networks of mobile devices to support the ad hoc social networks of the people who wear them. It could be understood as a longer yet more technical term for “smart mob”.
Ad hoc means that the organizing among people and their devices is done informally and on the fly (the way texting young people everywhere coordinate meetings after school). Social network means that every individual in a smart mob is a “node” in the jargon of social network analysis, with social “links” to other individuals, while social links means channels of communication and social bonds. The mobile thus is already self-evident as thousands and millions of people now are using mobile phones and SMS. Altogether, the fundamental elements of social networks formed by humans and communication networks constructed from optical cables and wireless devices, the nodes and links, is the answer why new communication technologies make possible profound social changes.
It is self-organizing, fully decentralized, and highly dynamic. It was argued that ad hoc social network opens the opportunity for many new invented devices to take part in our everyday social interactions with people. "Their ability to establish communication links among devices during face-to-face encounters can be used to facilitate, augment or even promote human social interactions" [1].
Examples of Mobile Ad Hoc and Social Network
- Ad hoc meetings,
- Mobile patient monitoring,
- Distributed command and Control systems
- Ubiquitous computing
[edit] Ad hoc hypothesis
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In philosophy and science, ad hoc often means the addition of corollary hypotheses or adjustment to a philosophical or scientific theory to save the theory from being falsified by compensating for anomalies not anticipated by the theory in its unmodified form. Philosophers and scientists are often suspicious or skeptical of theories that rely on continual, inelegant adjustments, and ad hoc hypotheses are often a characteristic of pseudoscientific subjects. See Skeptic's Dictionary: Ad hoc hypothesis. Much of scientific understanding relies on the modification of existing hypotheses or theories, but these are distinguished from ad hoc hypotheses in that the anomalies being explained propose a new means of being falsified.
Ideas that have been empirically tested and frequently require numerous ad hoc hypotheses to sustain them include applied kinesiology, astrology, sociobiology, biorhythms, creationism, facilitated communication, plant perception, and ESP.[1]
Hypotheses presented ad-hoc are not necessarily incorrect, however. An interesting example of an apparently supported ad hoc hypothesis is Albert Einstein's addition of the cosmological constant to relativity in order to allow a steady-state universe. Although he later referred to it as his "greatest blunder," it has been found to correspond quite well to the theories of dark energy.
[edit] Ad hoc pronunciation
Many reference works employ ad hoc pronunciation schemas as a way of indicating how words are pronounced. These are especially popular in U.S. published works[citation needed], such as the Merriam-Webster dictionary. An example of an ad hoc pronunciation would be "DIK-shuh-nair-ee", where the capitalization shows which syllable is stressed. This is in contrast to systems such as the International Phonetic Alphabet, which attempt to put pronunciation schemes on a standard footing.
Critics of ad hoc schemes point out that such schemas are inherently self-referential, since they rely on the ability of the reader to already know how a large number of words are commonly pronounced. In addition, such schemas often assume a certain language, dialect or accent on the part of the reader, and due to its popularity in the US, this is very often a US accent.
As its name suggests, there is no "standard" ad hoc schema, and so examples will vary considerably according to the publication's whim. In contrast, the IPA seeks to base pronunciation solely on vocal tract configurations and on the phonemes produced, though very often neo-common simple words are used to illustrate how the IPA applies in a specific language.
Proponents of ad hoc claim that it is much easier to use than IPA, though will often concur that this is usually only because the pronunciation is already known.
[edit] Ad hoc querying
Ad hoc querying is a term in information science.
Many application software 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-based system without the need for the in-depth knowledge of SQL, or database schema that a programmer would have.
Because such reporting has the potential to severely degrade the performance of a live system, it is sometimes provided only on a regularly-refreshed copy of the "live" database. Depending on the context, such a copy might be referred to as a data warehouse and the querying as data mining.
[edit] See also
[edit] References
- ^ Howard 2002, pp.169-171
[edit] Citations
- Howard, R, (2002). "Smart Mobs: the Next Social Revolution", Perseus.
[edit] External links
