Contiguity
Encyclopedia
A contiguity is a continuous mass, or a series of things in contact or proximity. In a different meaning, contiguity is the state of being contiguous. The concept was first set out in the Law of Contiguity, one of Aristotle
Aristotle
Aristotle was a Greek philosopher and polymath, a student of Plato and teacher of Alexander the Great. His writings cover many subjects, including physics, metaphysics, poetry, theater, music, logic, rhetoric, linguistics, politics, government, ethics, biology, and zoology...

's Laws of Association, which states that things which occur in proximity to each other in time
Time
Time is a part of the measuring system used to sequence events, to compare the durations of events and the intervals between them, and to quantify rates of change such as the motions of objects....

 or space
Space
Space is the boundless, three-dimensional extent in which objects and events occur and have relative position and direction. Physical space is often conceived in three linear dimensions, although modern physicists usually consider it, with time, to be part of a boundless four-dimensional continuum...

 are readily associated.

Biology

A cluster of genes that are located close to one another at a chromosome locus are termed contiguous. Contiguous gene disorders result from deletions or duplications of a chromosome segment, thus causing a contiguous gene imbalance.
Also, Contiguity refers to the way Taxonomy is ordered and formed after Charles Darwin wrote his famous, Theory of the Origins of Species in 1859. Prior to this a more strict taxonomy based upon an organisms locomotion and mobility was used. Now, we still use a type which is based on contiguity where the changes in an organism's anatomy are tracked and classed over time, thus showing a contiguous shaping over time.

Computer science

Elements of memory are contiguous if they are adjacent to one another and appear to be connected, but may in fact be disconnected. A computer file
Computer file
A computer file is a block of arbitrary information, or resource for storing information, which is available to a computer program and is usually based on some kind of durable storage. A file is durable in the sense that it remains available for programs to use after the current program has finished...

 or other data
Data (computing)
In computer science, data is information in a form suitable for use with a computer. Data is often distinguished from programs. A program is a sequence of instructions that detail a task for the computer to perform...

 stored on a mass storage
Mass storage
In computing, mass storage refers to the storage of large amounts of data in a persisting and machine-readable fashion. Devices and/or systems that have been described as mass storage include tape libraries, RAID systems, hard disk drives, magnetic tape drives, optical disc drives, magneto-optical...

 system, particularly hard disk
Hard disk
A hard disk drive is a non-volatile, random access digital magnetic data storage device. It features rotating rigid platters on a motor-driven spindle within a protective enclosure. Data is magnetically read from and written to the platter by read/write heads that float on a film of air above the...

-based, is said to be contiguous—sometimes, ungramatically, to be composed of one fragment—if the file data is in one continuous region without intervening extraneous data. A non-contiguous file is said to be fragmented
File system fragmentation
In computing, file system fragmentation, sometimes called file system aging, is the inability of a file system to lay out related data sequentially , an inherent phenomenon in storage-backed file systems that allow in-place modification of their contents. It is a special case of data fragmentation...

, and can usually be defragmented
Defragmentation
In the maintenance of file systems, defragmentation is a process that reduces the amount of fragmentation. It does this by physically organizing the contents of the mass storage device used to store files into the smallest number of contiguous regions . It also attempts to create larger regions of...

 with appropriate software.

Geography

Land which are in physical contact with one another. In the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

, for example, the "48 contiguous states
Contiguous United States
The contiguous United States are the 48 U.S. states on the continent of North America that are south of Canada and north of Mexico, plus the District of Columbia....

" exclude the states of Hawaii
Hawaii
Hawaii is the newest of the 50 U.S. states , and is the only U.S. state made up entirely of islands. It is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean, southwest of the continental United States, southeast of Japan, and northeast of...

 and Alaska
Alaska
Alaska is the largest state in the United States by area. It is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...

, which do not share borders with other U.S. state
U.S. state
A U.S. state is any one of the 50 federated states of the United States of America that share sovereignty with the federal government. Because of this shared sovereignty, an American is a citizen both of the federal entity and of his or her state of domicile. Four states use the official title of...

s.

Two or more contiguous municipalities
Municipality
A municipality is essentially an urban administrative division having corporate status and usually powers of self-government. It can also be used to mean the governing body of a municipality. A municipality is a general-purpose administrative subdivision, as opposed to a special-purpose district...

 can be consolidated into one, or one municipality can consist of many noncontiguous elements. For example, the Financially Distressed Municipalities Act
Financially Distressed Municipalities Act
The Financially Distressed Municipalities Act , also known as Act 47, empowers the Pennsylvania Department of Community and Economic Development to declare certain municipalities as financially distressed...

 allows the commonwealth of Pennsylvania
Pennsylvania
The Commonwealth of Pennsylvania is a U.S. state that is located in the Northeastern and Mid-Atlantic regions of the United States. The state borders Delaware and Maryland to the south, West Virginia to the southwest, Ohio to the west, New York and Ontario, Canada, to the north, and New Jersey to...

 to merge contiguous municipalities to reduce financial distress
Financial distress
Financial distress is a term in Corporate Finance used to indicate a condition when promises to creditors of a company are broken or honored with difficulty. Sometimes financial distress can lead to bankruptcy...

.

Geographic contiguity is important in biology
Biology
Biology is a natural science concerned with the study of life and living organisms, including their structure, function, growth, origin, evolution, distribution, and taxonomy. Biology is a vast subject containing many subdivisions, topics, and disciplines...

, especially animal ranges
Range (biology)
In biology, the range or distribution of a species is the geographical area within which that species can be found. Within that range, dispersion is variation in local density.The term is often qualified:...

. For a particular species, its habitat may be a 'contiguous range', or it might be broken, requiring periodic, typically seasonal migrations; (see: Disjunct distribution
Disjunct distribution
In biology, a taxon with a disjunct distribution is one that has two or more groups that are related but widely separated from each other geographically...

). The same concept of contiguous range is true for human transportation studies in an attempt to understand census geography. It also comes into play with electoral geography and politics.

Interaction design

Contiguous data is recognized by the fact that it needs to be in a particular order to keep its meaning: if you would scramble the letters, words or even the paragraphs in a text it wouldn't be the same text anymore.

Management

The concept of close operational context is an approach to determine the co-operation of entities, e.g. persons or persons with equipment, to monitor the usage of equipment just by an fuzzy metrics
Fuzzy locating system
Fuzzy locating is a rough but reliable method based on appropriate measuring technology for estimating a location of an object. The concept of precise or ‘’crisp locating’’ is replaced with respect to the operational requirements and the economic viability...

 for lateral distance, as else the events of coooperation or, in healthcare, especially the events of service by staff to patients.

Mathematics

The ideas of closeness are inherent in the concept of a contiguity space or proximity space
Proximity space
In topology, a proximity space is an axiomatization of notions of "nearness" that hold set-to-set, as opposed to the better known point-to-set notions that characterize topological spaces....

. See also Law of Continuity
Law of Continuity
The Law of Continuity is a heuristic principle introduced by Leibniz based on earlier work by Nicholas of Cusa and Johannes Kepler. It is the principle that "whatever succeeds for the finite, also succeeds for the infinite"...

. In addition, the Law of Continuity can be applied to conceptual computational abstract ideas.

Philosophy

Philosophers speak of contiguity when they assume two events or objects lying directly side by side in space and time without being connected by causality or any other principle.

Physics

Contiguity is a metallurgical property used to characterize microstructure of materials. It is computed by finding the ratio of solid–solid length to the sum of solid–solid and solid–liquid length of the microstructure.

Probability theory

The contiguity of a pair of sequences of probability measures is a property that relates to the commonality of the sets which have zero measure as the index in the sequence increases: see Contiguity (probability theory)
Contiguity (probability theory)
In probability theory, two sequences of probability measures are said to be contiguous if asymptotically they share the same support. Thus the notion of contiguity extends the concept of absolute continuity to the sequences of measures....

.

Psychology

Association by contiguity is the principle that ideas, memories, and experiences are linked when one is frequently experienced with the other. For example, if you constantly see a knife and a fork together they become linked (associated). The more these two items (stimuli) are perceived together the stronger the link between them. When one of the memories becomes activated later on, the linked (contiguously associated) memory becomes temporarily more activated and thus easier to be called into working memory. This process is known as priming
Priming (psychology)
Priming is an implicit memory effect in which exposure to a stimulus influences a response to a later stimulus. It can occur following perceptual, semantic, or conceptual stimulus repetition...

, and the initial memory that primed the other is known as the retrieval cue.

Association by contiguity is the root of association by similarity. Association by similarity is the idea that one memory primes another through their common property or properties. Thus, an apple may prime a memory of a rose through the common property of red. These two become associated even though you may have never experienced an apple and a rose together (consistent with association by contiguity).

In the study of human memory, the contiguity effect has been found in studies of free recall. Analyses of free recall data indicates that there tends to be the greatest number of +/- 1 transitions between words, suggesting that words that are closer together in a list are more likely to be recalled together (). This is shown in a graph of conditional response probability as a function of lag as originated by Dr. Michael Kahana. The probability of recall (y-axis) is plotted against the lag, or separation between subsequently recalled words also see figure http://memory.psych.upenn.edu/Research?action=AttachFile&do=get&target=crp2a_square.jpg. For example, if two items A and B are learned together, when cued with B, A is retrieved and vice-versa due to their temporal contiguity, although there will be a stronger forward association (when cued with A, B is recalled) .

The contiguity effect appears relatively constant, and has been predicted to have long-term effects according to the temporal context model proposed by Howard and Kahana . This model explains the contiguity effect in the following manner: when an item is presented, it activates the temporal context that was active when the item was originally studied. Since contexts of neighboring items overlap, and that overlap increases with decreasing lag between items, a contiguity effect results (). The contiguity effect has even been found between items in different lists, although it has been speculated that these items could simply be intrusions (

When one associated memory, a group of associated memories, or a whole line of associated memories becomes primed, this is known as spreading activation
Spreading activation
Spreading activation is a method for searching associative networks, neural networks, or semantic networks. The search process is initiated by labeling a set of source nodes with weights or "activation" and then iteratively propagating or "spreading" that activation out to other nodes linked to...

.

In conditioning
Operant conditioning
Operant conditioning is a form of psychological learning during which an individual modifies the occurrence and form of its own behavior due to the association of the behavior with a stimulus...

, contiguity refers to how associated a reinforcer
Reinforcement
Reinforcement is a term in operant conditioning and behavior analysis for the process of increasing the rate or probability of a behavior in the form of a "response" by the delivery or emergence of a stimulus Reinforcement is a term in operant conditioning and behavior analysis for the process of...

 is with behaviour. The higher the contiguity between events the greater the strength of the behavioural relationship.

Edwin Ray Guthrie
Edwin Ray Guthrie
Edwin Ray Guthrie was a philosopher, mathematician, and later became a behavior psychologist. Guthrie is best known for his one trial theory, nonreinforcement, and contiguity learning. One word that could describe Guthrie is “simple." His approach to learning and theories was simple...

's contiguity theory deals with patterned movements.
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