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Cube

In geometry, a cube is a three-dimensional solid object bounded by six square faces. It has twelve edges and eight vertices. It can be represented as the rectangular cuboid with six faces are all squares, and parallelepiped with the edges are all equal. It is an example of many type of solids: Platonic solid, regular polyhedron, parallelohedron, zonohedron, and plesiohedron. The dual polyhedron of a cube is the regular octahedron.

The cube can be represented in many ways, one of which is the graph known as the cubical graph. It can be constructed by using the Cartesian product of graphs. The cube was discovered in antiquity. It was associated with the nature of earth by Plato, the founder of Platonic solid. It was used as the part of the Solar System, proposed by Johannes Kepler. It can be derived differently to create more polyhedrons, and it has applications to construct a new polyhedron by attaching others. It can be generalized as tesseract in four-dimensional space.

Properties
A cube is a special case of rectangular cuboid in which the edges are equal in length. Like other cuboids, every face of a cube has four vertices, each of which connects with three congruent lines. These edges form square faces, making the dihedral angle of a cube between every two adjacent squares being the interior angle of a square, 90°. Hence, the cube has six faces, twelve edges, and eight vertices. Because of such properties, it is categorized as one of the five Platonic solids, a polyhedron in which all the regular polygons are congruent and the same number of faces meet at each vertex.

Measurement and other metric properties
Given that a cube with edge length $$ a $$. The face diagonal of a cube is the diagonal of a square $$ a\sqrt{2} $$, and the space diagonal of a cube is a line connecting two vertices that is not in the same face, formulated as $$ a \sqrt{3} $$. Both formulas can be determined by using Pythagorean theorem. The surface area of a cube $$ A $$ is six times the area of a square: $$ A = 6a^2. $$ The volume of a cuboid is the product of length, width, and height. Because the edges of a cube are all equal in length, it is: $$ V = a^3. $$

A unit cube is a special case where each cube's edge is 1 unit length. The surface area and the volume of a unit cube is 1. It has Rupert property, meaning a polyhedron with the same or larger size can pass through into the hole of the unit cube. The Prince Rupert's cube, named after Prince Rupert of the Rhine, is the largest cube that can fit inside, with the size being 6% larger.

A geometric problem of doubling the cube—alternatively known as the Delian problem—requires the construction of a cube with a volume twice the original by using a compass and straightedge solely. Ancient mathematicians could not solve this old problem until French mathematician Pierre Wantzel in 1837 proved it was impossible.

Relation to the spheres
With edge length $$ a $$, the inscribed sphere of a cube is the sphere tangent to the faces of a cube at their centroids, with radius $ \frac{1}{2}a $. The midsphere of a cube is the sphere tangent to the edges of a cube, with radius $ \frac{1}{\sqrt{2}}a $. The circumscribed sphere of a cube is the sphere tangent to the vertices of a cube, with radius $ \frac{\sqrt{3}}{2}a $.

For a cube whose circumscribed sphere has radius $$ R $$, and for a given point in its three-dimensional space with distances $$ d_i $$ from the cube's eight vertices, it is: $$ \frac{1}{8}\sum_{i=1}^8 d_i^4 + \frac{16R^4}{9} = \left(\frac{1}{8}\sum_{i=1}^8 d_i^2 + \frac{2R^2}{3}\right)^2. $$

Symmetry
The cube has octahedral symmetry $$ \mathrm{O}_\mathrm{h} $$. It is composed of reflection symmetry, a symmetry by cutting into two halves by a plane. There are nine reflection symmetries: the five are cut the cube from the midpoints of its edges, and the four are cut diagonally. It is also composed of rotational symmetry, a symmetry by rotating it around the axis, from which the appearance is interchangeable. It has octahedral rotation symmetry $$ \mathrm{O} $$: three axes pass through the cube's opposite faces centroid, six through the cube's opposite edges midpoints, and four through the cube's opposite vertices; each of these axes is respectively four-fold rotational symmetry (0°, 90°, 180°, and 270°), two-fold rotational symmetry (0° and 180°), and three-fold rotational symmetry (0°, 120°, and 240°).

The dual polyhedron can be obtained from each of the polyhedron's vertices tangent to a plane by the process known as polar reciprocation. One property of dual polyhedrons generally is that the polyhedron and its dual share their three-dimensional symmetry point group. In this case, the dual polyhedron of a cube is the regular octahedron, and both of these polyhedron has the same symmetry, the octahedral symmetry.

The cube is face-transitive, meaning its two squares are alike and can be mapped by rotation and reflection. It is vertex-transitive, meaning all of its vertices are equivalent and can be mapped isometrically under its symmetry. It is also edge-transitive, meaning the same kind of faces surround each of its vertices in the same or reverse order, all two adjacent faces have the same dihedral angle. Therefore, the cube is regular polyhedron because it requires those properties.

Classifications
The cube is a special case among every cuboids. As mentioned above, the cube can be represented as the rectangular cuboid with edges equal in length and all of its faces are all squares. The cube may be considered as the parallelepiped in which all of its edges are equal edges.

The cube is one of the types of parallelohedron, meaning it is a polyhedron that can be translated without rotating to fill a space—called honeycomb—in which all of its copies are being attached. Every three-dimensional parallelohedron is zonohedron, a centrally symmetric polyhedron whose faces are centrally symmetric polygons, and it is plesiohedron, a special kind of space-filling polyhedron that can be defined as the Voronoi cell of a symmetric Delone set.

Construction
An elementary way to construct a cube is using the net. A net is an arrangement of edge-joining polygons constructing a polyhedron by connecting along the edges of those polygons. Here, there are eleven different cube's net.

In analytic geometry, a cube may be constructed using the Cartesian coordinate systems. For a cube centered at the origin, with edges parallel to the axes and with an edge length of 2, the Cartesian coordinates of the vertices are $$ (\pm 1, \pm 1, \pm 1) $$. Its interior consists of all points $$ (x_0, x_1, x_2) $$ with $$ -1 < x_i < 1 $$ for all $$ i $$. A cube's surface with center $$ (x_0, y_0, z_0) $$ and edge length of $$ 2a $$ is the locus of all points $$ (x,y,z) $$ such that $$ \max\{ |x-x_0|,|y-y_0|,|z-z_0| \} = a.$$

The cube is Hanner polytope, because it can be constructed by using Cartesian product of three line segments. Its dual polyhedron, the regular octahedron, is constructed by direct sum of three line segments.

As a graph
According to Steinitz's theorem, the graph can be represented as the skeleton of a polyhedron; roughly speaking, a framework of a polyhedron. Such a graph has two properties. It is planar, meaning the edges of a graph are connected to every vertex without crossing other edges. It is also 3-connected graph, meaning that, whenever a graph with more than three vertices, and two of the vertices are removed, the edges remain connected. The skeleton of a cube can be represented as the graph, and it is called the cubical graph, a Platonic graph. It has the same number of vertices and edges as the cube, twelve vertices and eight edges.

The cubical graph is a special case of hypercube graph or $n$-cube—denoted as $$ Q_n $$—because it can be constructed by using the operation known as the Cartesian product of graphs. To put it in a plain, its construction involves two graphs connecting the pair of vertices with an edge to form a new graph. In the case of the cubical graph, it is the product of two $$ Q_2 $$; roughly speaking, it is a graph resembling a square. In other words, the cubical graph is constructed by connecting each vertex of two squares with an edge. Notationally, the cubical graph can be denoted as $$ Q_3 $$. It is a unit distance graph.

Like other graphs of cuboids, the cubical graph is also classified as the prism graph.

In orthogonal projection
An object illuminated by parallel rays of light casts a shadow on a plane perpendicular to those rays, called an orthogonal projection. A polyhedron is considered equiprojective if, for some position of the light, its orthogonal projection is a regular polygon. The cube is equiprojective because, if the light is parallel to one of the four lines joining a vertex to the opposite vertex, its projection is a regular hexagon. Conventionally, the cube is 6-equiprojective.

As a configuration matrix
The cube can be represented as configuration matrix. A configuration matrix is a matrix in which the rows and columns correspond to the elements of a polyhedron as in the vertices, edges, and faces. The diagonal of a matrix denotes the number of each element that appears in a polyhedron, whereas the non-diagonal of a matrix denotes the number of the column's elements that occur in or at the row's element. As mentioned above, the cube has eight vertices, twelve edges, and six faces; each element in a matrix's diagonal is denoted as 8, 12, and 6. The first column of the middle row indicates that there are two vertices in (i.e., at the extremes of) each edge, denoted as 2; the middle column of the first row indicates that three edges meet at each vertex, denoted as 3. The following matrix is: $$ \begin{bmatrix}\begin{matrix}8 & 3 & 3 \\ 2 & 12 & 2 \\ 4 & 4 & 6 \end{matrix}\end{bmatrix}$$

In antiquity
The Platonic solid is a set of polyhedrons known since antiquity. It was named after Plato in his Timaeus dialogue, who attributed these solids with nature. One of them, the cube, represented the classical element of earth because of its stability. Euclid's Elements defined the Platonic solids, including the cube, and using these solids with the problem involving to find the ratio of the circumscribed sphere's diameter to the edge length.

Following its attribution with nature by Plato, Johannes Kepler in his Harmonices Mundi sketched each of the Platonic solids, one of them is a cube in which Kepler decorated a tree on it. In his Mysterium Cosmographicum, Kepler also proposed the Solar System by using the Platonic solids setting into another one and separating them with six spheres resembling the six planets. The ordered solids started from the innermost to the outermost: regular octahedron, regular icosahedron, regular dodecahedron, regular tetrahedron, and cube.

Polyhedron, honeycombs, and polytopes
The cube can appear in the construction of a polyhedron, and some of its types can be derived differently in the following:
 * When faceting a cube, meaning removing part of the polygonal faces without creating new vertices of a cube, the resulting polyhedron is the stellated octahedron.
 * Attaching a square pyramid to each square face of a cube produces its Kleetope, a polyhedron known as the tetrakis hexahedron. Suppose one and two equilateral square pyramids are attached to their square faces. In that case, they are the construction of an elongated square pyramid and elongated square bipyramid respectively, the Johnson solid's examples.
 * Each of the cube's vertices can be truncated, and the resulting polyhedron is the Archimedean solid, the truncated cube. When its edges are truncated, it is a rhombicuboctahedron. Relatedly, the rhombicuboctahedron can also be constructed by separating the cube's faces and then spreading away, after which adding other triangular and square faces between them; this is known as the "expanded cube". It also can be constructed similarly by the cube's dual, the regular octahedron.
 * The snub cube is an Archimedean solid that can be constructed by separating away the cube square's face, and filling their gaps with twisted angle equilateral triangles;a process known as snub.

The honeycomb is the space-filling or tessellation in three-dimensional space, meaning it is an object in which the construction begins by attaching any polyhedrons onto their faces without leaving a gap. The cube can be represented as the cell, and examples of a honeycomb are cubic honeycomb, order-5 cubic honeycomb, order-6 cubic honeycomb, and order-7 cubic honeycomb. The cube can be constructed with six square pyramids, tiling space by attaching their apices.

Polycube is a polyhedron in which the faces of many cubes are attached. Analogously, it can be interpreted as the polyominoes in three-dimensional space. When four cubes are stacked vertically, and the other four are attached to the second-from-top cube of the stack, the resulting polycube is Dali cross, after Salvador Dali. The Dali cross is a tile space polyhedron, which can be represented as the net of a tesseract. A tesseract is a cube analogous' four-dimensional space bounded by twenty-four squares, and it is bounded by the eight cubes known as its cells.

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title: Cube


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Commuter rail

Commuter rail, or suburban rail, is a passenger rail transport service that primarily operates within a metropolitan area, connecting commuters to a central city from adjacent suburbs or commuter towns. Commuter rail systems are considered heavy rail, using electric or diesel trains. Distance charges or zone pricing may be used.

The term can refer to systems with a wide variety of different features and service frequencies, but is often used in contrast to rapid transit or light rail.

Some services share similarities with both commuter rail and high-frequency rapid transit; examples include the German S-Bahn in some cities, the Réseau Express Régional (RER) in Paris, the S Lines in Milan, many Japanese commuter systems, the East Rail line in Hong Kong, and some Australasian suburban networks, such as Sydney Trains. Many commuter rail systems share tracks with other passenger services and freight.

In North America, commuter rail sometimes refers only to systems that primarily operate during peak periods and offer little to no service for the rest of the day, with regional rail being used to refer to systems that offer all-day service.

Characteristics

Most commuter (or suburban) trains are built to main line rail standards, differing from light rail or rapid transit (metro rail) systems by:
 * being larger
 * providing more seating and less standing room, owing to the longer distances involved
 * having (in most cases) a lower frequency of service
 * having scheduled services (i.e. trains run at specific times rather than at specific intervals)
 * serving lower-density suburban areas, typically connecting suburbs to the city center
 * sharing track or right-of-way with intercity and/or freight trains
 * not fully grade separated (containing at-grade crossings with crossing gates)
 * being able to skip certain stations as an express service due to normally being driver controlled

Train schedule
Compared to rapid transit (or metro rail), commuter/suburban rail often has lower frequency, following a schedule rather than fixed intervals, and fewer stations spaced further apart. They primarily serve lower density suburban areas (non inner-city), generally only having one or two stops in a city's central business district, and often share right-of-way with intercity or freight trains. Some services operate only during peak hours and others use fewer departures during off peak hours and weekends. Average speeds are high, often 50 km/h (30 mph) or higher. These higher speeds better serve the longer distances involved. Some services include express services which skip some stations in order to run faster and separate longer distance riders from short-distance ones.

The general range of commuter trains' travel distance varies between 15 and 200 km (10 and 125 miles), but longer distances can be covered when the trains run between two or several cities (e.g. S-Bahn in the Ruhr area of Germany). Distances between stations may vary, but are usually much longer than those of urban rail systems. In city centres the train either has a terminal station or passes through the city centre with notably fewer station stops than those of urban rail systems. Toilets are often available on-board trains and in stations.

Track
Their ability to coexist with freight or intercity services in the same right-of-way can drastically reduce system construction costs. However, frequently they are built with dedicated tracks within that right-of-way to prevent delays, especially where service densities have converged in the inner parts of the network.

Most such trains run on the local standard gauge track. Some systems may run on a narrower or broader gauge. Examples of narrow gauge systems are found in Japan, Indonesia, Malaysia, Thailand, Taiwan, Switzerland, in the Brisbane (Queensland Rail's City network) and Perth (Transperth) systems in Australia, in some systems in Sweden, and on the Genoa-Casella line in Italy. Some countries and regions, including Finland, India, Pakistan, Russia, Brazil and Sri Lanka, as well as San Francisco (BART) in the US and Melbourne and Adelaide in Australia, use broad gauge track.

Metro
Metro rail and rapid transit usually cover smaller inner-urban areas within 12 to 20 km of city centers, with shorter stop spacing, use rolling stocks with larger standing spaces, lower top speed and higher acceleration, designed for short-distance travel. They also run more frequently, to a headway rather than a published timetable and use dedicated tracks (underground or elevated), whereas commuter rail often shares tracks, technology and the legal framework within mainline railway systems, and uses rolling stocks with more seating and higher speed for comfort on longer city-suburban journeys.

However, the classification as a metro or rapid rail can be difficult as both may typically cover a metropolitan area exclusively, run on separate tracks in the centre, and often feature purpose-built rolling stock. The fact that the terminology is not standardised across countries (even across English-speaking countries) further complicates matters. This distinction is most easily made when there are two (or more) systems such as New York's subway and the LIRR and Metro-North Railroad, Paris' Métro and RER along with Transilien, Washington D.C.'s Metro along with its MARC and VRE, London's tube lines of the Underground and the Overground, Elizabeth line, Thameslink along with other commuter rail operators, Madrid's Metro and Cercanías, Barcelona's Metro and Rodalies, and Tokyo's subway and the JR lines along with various privately owned and operated commuter rail systems.

Regional rail
Regional rail usually provides rail services between towns and cities, rather than purely linking major population hubs in the way inter-city rail does. Regional rail operates outside major cities. Unlike Inter-city, it stops at most or all stations between cities. It provides a service between smaller communities along the line that are often byproducts of ribbon developments, and also connects with long-distance services at interchange stations located at junctions, terminals, or larger towns along the line. Alternative names are "local train" or "stopping train". Examples include the former BR's Regional Railways, France's TER (Transport express régional), Germany's Regionalexpress and Regionalbahn, and South Korea's Tonggeun and Mugunghwa-ho services.

Inter-city rail
In some European countries, the distinction between commuter trains and long-distance/intercity trains is subtle, due to the relatively short distances involved. For example, so-called "intercity" trains in Belgium and the Netherlands carry many commuters, while their equipment, range, and speeds are similar to those of commuter trains in some larger countries.

The United Kingdom has a privatised rail system, with different routes and services covered by different private operators. The distinction between commuter and intercity rail is not as clear as it was before privatisation (when InterCity existed as a brand of its own), but usually it is still possible to tell them apart. Some operators, for example Thameslink, focus solely on commuter services. Others, such as Avanti West Coast and LNER, run solely intercity services. Others still, such as GWR and EMR, run a mixture of commuter, regional and intercity services. Some of these operators use different branding for different types of service (for example EMR brands its trains as either "InterCity", "Connect" for London commuter services, and "Regional") but even for those operators that do not, the type of train, amenities offered, and stopping pattern, usually tell the services apart.

Russian commuter trains, on the other hand, frequently cover areas larger than Belgium itself, although these are still short distances by Russian standards. They have a different ticketing system from long-distance trains, and in major cities they often operate from a separate section of the train station.

Some consider "inter-city" service to be that which operates as an express service between two main city stations, bypassing intermediate stations. However, this term is used in Australia (Sydney for example) to describe the regional trains operating beyond the boundaries of the suburban services, even though some of these "inter-city" services stop all stations similar to German regional services. In this regard, the German service delineations and naming conventions are clearer and better used for academic purposes.

High-speed rail
Sometimes high-speed rail can serve daily use of commuters. The Japanese Shinkansen high speed rail system is heavily used by commuters in the Greater Tokyo Area, who commute between 100 and 200 km by Shinkansen. To meet the demand of commuters, JR sells commuter discount passes. Before 2021, they operated 16-car bilevel E4 Series Shinkansen trains at rush hour, providing a capacity of 1,600 seats. Several lines in China, such as the Beijing–Tianjin Intercity Railway and the Shanghai–Nanjing High-Speed Railway, serve a similar role with many more under construction or planned.

In South Korea, some sections of the high-speed rail network are also heavily used by commuters, such as the section between Gwangmyeong Station and Seoul Station on the KTX network (Gyeongbu HSR Line), or the section between Dongtan Station and Suseo station on the SRT Line.

The high-speed services linking Zürich, Bern and Basel in Switzerland (200 km/h) have brought the Central Business Districts (CBDs) of these three cities within 1 hour of each other. This has resulted in unexpectedly high demand for new commuter trips between the three cities and a corresponding increase in suburban rail passengers accessing the high-speed services at the main city-centre stations (Hauptbahnhof). The Regional-Express commuter service between Munich and Nuremberg in Germany runs at 200 km/h on the 300 km/h Nuremberg–Ingolstadt high-speed railway.

The regional trains Stockholm–Uppsala, Stockholm–Västerås, Stockholm–Eskilstuna and Gothenburg–Trollhättan in Sweden reach 200 km/h and have many daily commuters.

In Great Britain, the HS1 domestic services between London and Ashford runs at a top speed of 225 km/h, and in peak hours the trains can be full with commuters standing.

The Athens Suburban Railway in Greece consists of five lines, 4 of which are electrified. The Kiato–Piraeus line and the Aigio–Airport lines reach speeds of up to 180 km/h. The Athens–Chalcis line is also expected to attain speeds of up to 200 km/h upon upgrading of the SKA–Oinoi railway sector. These lines also have many daily commuters, with the number expected to rise even higher upon full completion of the Acharnes Railway Center.

Eskişehir-Ankara and Konya-Ankara high speed train routes serve as high speed commuter trains in Turkey.

Train types
Commuter/suburban trains are usually optimized for maximum passenger volume, in most cases without sacrificing too much comfort and luggage space, though they seldom have all the amenities of long-distance trains. Cars may be single- or double-level, and aim to provide seating for all. Compared to intercity trains, they have less space, fewer amenities and limited baggage areas.

Multiple unit type
Commuter rail trains are usually composed of multiple units, which are self-propelled, bidirectional, articulated passenger rail cars with driving motors on each (or every other) bogie. Depending on local circumstances and tradition they may be powered either by diesel engines located below the passenger compartment (diesel multiple units) or by electricity picked up from third rails or overhead lines (electric multiple units). Multiple units are almost invariably equipped with control cabs at both ends, which is why such units are so frequently used to provide commuter services, due to the associated short turn-around time.

Locomotive hauled services
Locomotive hauled services are used in some countries or locations. This is often a case of asset sweating, by using a single large combined fleet for intercity and regional services. Loco hauled services are usually run in push-pull formation, that is, the train can run with the locomotive at the "front" or "rear" of the train (pushing or pulling). Trains are often equipped with a control cab at the other end of the train from the locomotive, allowing the train operator to operate the train from either end. The motive power for locomotive-hauled commuter trains may be either electric or diesel–electric, although some countries, such as Germany and some of the former Soviet-bloc countries, also use diesel–hydraulic locomotives.

Seat plans
In the US and some other countries, a three-and-two seat plan is used. Middle seats on these trains are often less popular because passengers feel crowded and uncomfortable.

In Japan, South Korea and Indonesia, longitudinal (sideways window-lining) seating is widely used in many commuter rail trains to increase capacity in rush hours. Carriages are usually not organized to increase seating capacity (although in some trains at least one carriage would feature more doors to facilitate easier boarding and alighting and bench seats so that they can be folded up during rush hour to provide more standing room) even in the case of commuting longer than 50 km and commuters in the Greater Tokyo Area, Seoul metropolitan area, and Jabodetabek area have to stand in the train for more than an hour.

Africa
Currently there are not many examples of commuter rail in Africa. Metrorail operates in the major cities of South Africa, and there are some commuter rail services in Algeria, Botswana, Kenya, Morocco, Egypt and Tunisia. In Algeria, SNTF operates commuter rail lines between the capital Algiers and its southern and eastern suburbs. They also serve to connect Algiers' main universities to each other. The Dar es Salaam commuter rail offers intracity services in Dar es Salaam, Tanzania. In Botswana, the (Botswana Railways) "BR Express" has a commuter train between Lobatse and Gaborone.

East Asia
In Japan, commuter rail systems have extensive network and frequent service and are heavily used. In many cases, Japanese commuter rail is operationally more like a typical metro system (frequent trains, an emphasis on standing passengers, short station spacings) than it is like commuter rail in other countries. Japanese commuter rail commonly interline with city center subway lines, with commuter rail trains continuing into the subway network, and then out onto different commuter rail systems on the other side of the city. Many Japanese commuter systems operate various stopping patterns to reduce the travel time to distant locations, often using station passing loops instead of dedicated express tracks. It is notable that the larger Japanese commuter rail systems are owned and operated by for-profit private railway companies, without public subsidy.

East Japan Railway Company operates a large suburban train network in Tokyo with various lines connecting the suburban areas to the city center. While the Yamanote Line, Keihin Tohoku Line, Chūō–Sōbu Line services arguably are more akin to rapid transit with frequent stops, simple stopping patterns (relative to other JR East lines) no branching services and largely serving the inner suburbs; other services along the Chūō Rapid Line, Sōbu Rapid Line/Yokosuka Line, Ueno–Tokyo Line, Shōnan–Shinjuku Line etc. are mid-distance services from suburban lines in the outer reaches of Greater Tokyo through operating into these lines to form a high frequency corridor though central Tokyo.

Other commuter rail routes in Japan include:
 * Hanshin Namba Line and Kintetsu Namba Line have a busy east west underground section that allow trains from both Hanshin Electric Railway and Kintetsu Railway to access Namba, a major commercial center of Osaka, and service destinations east and west of Osaka.
 * Osaka Metro Sakaisuji Line is a north south line that allows Hankyu services from the Senri Line, Kyoto Main Line and Arashiyama Line to enter Osaka city center.
 * JR West Tozai Line is an underground east west corridor allowing trains from the Kobe Line, Takarazuka Line and Gakkentoshi Line to access Umeda in central Osaka.
 * JR West Osaka Loop Line is a mostly elevated loop line that allows for services from the Yamatoji Line, Hanwa Line and Sakurajima Line to loop around central Osaka.
 * JR West Kobe Line/Kyoto Line is a four track corridor allowing Biwako Line, Kosei Line, Takarazuka Line, San'yō Main Line and Akō Line services to service Kyoto, Osaka and Kobe.
 * A special private railway Kōbe Rapid Transit Railway owns two underground corridors (a north south and east west line) that allow for Sanyo Electric Railway, Hankyu railway, Hanshin Electric Railway and Kobe Electric Railway services to enter and cross Kobe city center.
 * Most of the trains on the Meitetsu network through operate into a high frequency trunk line on the Meitetsu Nagoya Main Line branching out to other lines on the other side of Nagoya.

Commuter rail systems have been inaugurated in several cities in China such as Beijing, Shanghai, Zhengzhou, Wuhan, Changsha and the Pearl River Delta. With plans for large systems in northeastern Zhejiang, Jingjinji, and Yangtze River Delta areas. The level of service varies considerably from line to line ranging high to near high speeds. More developed and established lines such as the Guangshen Railway have more frequent metro-like service.

The two MTR lines which are owned and formerly operated by the Kowloon-Canton Railway Corporation (East Rail line and Tuen Ma line which is integrated from the former West Rail line and Ma On Shan line in 2021), then the "KCR"), and MTR's own Tung Chung line connect the new towns in New Territories and the city centre Kowloon together with frequent intervals, and some New Territories-bound trains terminate at intermediate stations, providing more frequent services in Kowloon and the towns closer to Kowloon. They use rolling stocks with a faster maximum speed and have longer stop spacing compard to other lines which only run in the inner urban area, but in order to maximise capacity and throughput, these rolling stocks have longitudinal seatings, 5 pairs of doors in each carriage with large standing spaces like the urban lines, and run as frequent as well. Most of the sections of these four lines are overground and some sections of the East Rail Line share tracks with intercity trains to mainland China. The three KCR lines are integrated into the MTR network since 2008 and most passengers do not need to exit and re-enter the system through separate fare gates and purchase separate tickets to transfer between such lines and the rest of the network (the exceptions are between the Tuen Ma line's East Tsim Sha Tsui station and the Tsuen Wan line's Tsim Sha Tsui station.

In Taiwan, the Western line in the Taipei-Taoyuan Metropolitan Area, Taichung Metropolitan Area and Tainan-Kaohsiung Metropolitan Area as well as the Neiwan-Liujia line in the Hsinchu Area are considered commuter rail.

In South Korea, the Seoul Metropolitan Subway includes a total of 22 lines, and some of its lines are suburban lines. This is especially the case for lines operated by Korail, such as the Gyeongui-Jungang Line, the Gyeongchun Line, the Suin-Bundang Line, or the Gyeonggang Line. Even some lines not operated by Korail, such as the AREX Line, the Seohae Line or the Shinbundang Line mostly function as commuter rail. Lastly, even for the "numbered lines" (1–9) of the Seoul Metropolitan Subway which mostly travel in the dense parts of Seoul, some track sections extend far outside of the city, and operate large sections at ground level, such as on the Line 1, Line 3 and Line 4. In Busan, the Donghae Line, while part of the Busan Metro system, mostly functions as a commuter rail line.

Southeast Asia

In Indonesia, the KRL Commuterline is the largest commuter rail system in the country, serving the Greater Jakarta. It connects the Jakarta city center with surrounding cities and sub-urbans in Banten and West Java provinces, including Depok, Bogor, Tangerang, Serpong, Rangkasbitung, Bekasi and Cikarang. In July 2015, KRL Commuterline served more than 850,000 passengers per day, which is almost triple of the 2011 figures, but still less than 3.5% of all Jabodetabek commutes. Other commuter rail systems in Indonesia include the Metro Surabaya Commuter Line, Commuter Line Bandung, KAI Commuter Yogyakarta–Solo Line, Kedung Sepur, and the Sri Lelawangsa.

In the Philippines, the Philippine National Railways has two commuter rail systems currently operational; the PNR Metro Commuter Line in the Greater Manila Area and the PNR Bicol Commuter in the Bicol Region. A new commuter rail line in Metro Manila, the North–South Commuter Railway, is currently under construction. Its North section is set to be partially opened by 2021.

In Malaysia, there are two commuter services operated by Keretapi Tanah Melayu. They are the KTM Komuter that serves Kuala Lumpur and the surrounding Klang Valley area, and the KTM Komuter Northern Sector that serves Greater Penang, Perak, Kedah and Perlis in the northern region of Peninsular Malaysia.

In Thailand, the Greater Bangkok Commuter rail and the Airport Rail Link serve the Bangkok Metropolitan Region. The SRT Red Lines, a new commuter line in Bangkok, started construction in 2009. It opened in 2021.

Another commuter rail system in Southeast Asia is the Yangon Circular Railway in Myanmar.

South Asia
In India, commuter rail systems are present in major cities and form an important part of people's daily lives. Mumbai Suburban Railway, the oldest suburban rail system in Asia, carries more than 7.24 million commuters on a daily basis which constitutes more than half of the total daily passenger capacity of the Indian Railways itself. Kolkata Suburban Railway, one of the largest suburban railway networks in the world, consists of more than 450 stations and carries more than 3.5 million commuters per day. The Chennai Suburban Railway along with the Chennai MRTS, also covers over 300 stations and carries more than 2.5 million people daily to different areas in Chennai and its surroundings. Other commuter railways in India include the Hyderabad MMTS, Delhi Suburban Railway, Pune Suburban Railway and Lucknow-Kanpur Suburban Railway.

In 2020, Government of India approved Bengaluru Suburban Railway to connect Bengaluru and its suburbs. It will be unique and first of its kind in India as it will have metro like facilities and rolling stock.

In Bangladesh, there is one suburban rail called the Chittagong Circular Railway. Another suburban railway called the Dhaka Circular Railway is currently proposed.

Karachi in Pakistan has a circular railway since 1969.

West Asia
In Iran, SYSTRA proposed 4 express lines similar to RER suburban lines in Paris. Tehran Metro is going to construct express lines. For instance, the Rahyab Behineh, a consultant for Tehran Metro, is studying Tehran Express Line 2. Tehran Metro currently has a commuter line, which is Line 5 between Tehran and Karaj. Isfahan has two lines to its suburbs Baharestan and Fuladshahr under construction, and a third line to Shahinshahr is planned.

In Turkey; Başkentray, İZBAN, Marmaray and Gaziray are well-known examples.

Europe
Major metropolitan areas in most European countries are usually served by extensive commuter/suburban rail systems. Well-known examples include BG Voz in Belgrade (Serbia), S-Bahn in Germany, Austria and German-speaking areas of Switzerland, Proastiakos in Greece, RER in France and Belgium, Servizio ferroviario suburbano in Italy, Cercanías and Rodalies (Catalonia) in Spain, CP Urban Services in Portugal, Esko in Prague and Ostrava (Czech Republic), HÉV in Budapest (Hungary) and DART in Dublin (Ireland).

Western Europe
London has multiple commuter rail routes:
 * The Elizabeth line runs on a 22 km (14 mi)-long east–west twin tunnel under central London (Crossrail project) as its central core section.
 * Thameslink brings together several branches from northern and southern suburbs and satellite towns in to a high frequency central tunnel underneath London.
 * The London Overground, by contrast, skirts through the inner suburbs with lines mostly independent of each other, although there are several branches. The Watford DC line, partly shared with underground trains, uses third rail, but parallels a main line using overhead wires. The East London Line and North London Line run at metro-like frequencies in inner London, which make them nearly indistinguishable from metro systems apart from the fact that the tracks are shared with freight trains.
 * The Metropolitan line, despite being part of the London Underground, is a commuter rail route as it links the City of London to commuter towns outside Greater London such as Rickmansworth, Amersham and Chesham, where it runs to a timetable, being the only London Underground line with a public timetable published. It also shares tracks with Chiltern Railways main line services between London and Aylesbury.

The Merseyrail network in Liverpool consists of two commuter rail routes powered by third rail, both of which branch out at one end. At the other, the Northern Line continues out of the city centre to a mainline rail interchange, while the Wirral Line has a city-centre loop.

Birmingham has four suburban routes, one of which is operated with diesel trains.

The Tyneside Electrics system in Newcastle existed from 1904 to 1967 using DC third rail. British Rail did not have the budget to maintain the ageing electrification system. The Riverside Branch was closed, while the remaining lines were de-electrified. 13 years later, they were re-electrified using DC overhead wires, and now form the Tyne & Wear Metro Yellow Line.

Many of the rail services around Glasgow are branded as Strathclyde Partnership for Transport. The network includes most electrified Scottish rail routes.

The Metro run eleven services which feed into Leeds, connecting the city with commuter areas and neighbouring urban centres in the West Yorkshire Connurbation.

MetroWest is a proposed network in Bristol, northern Somerset & southern Gloucestershire. The four-tracking of the line between Bristol Temple Meads and Bristol Parkway stations will enable local rail services to be separated from long-distance trains.

The Réseau express régional d'Île-de-France (RER) is a commuter rail network in the agglomeration of Paris. In the centre the RER has high frequency underground corridors where several suburban branches feed similar to a rapid transit system.

Commuter rail systems in Germany are called S-Bahn. While in some major cities S-Bahn services run on separate lines exclusively other systems use the existing regional rail tracks.

In Italy fifteen cities have commuter rail systems:
 * Bari (Bari metropolitan railway service, 3 lines)
 * Bologna (Bologna metropolitan railway service, 8 lines)
 * Cagliari, 1 line
 * Catanzaro, 2 lines
 * Genoa (Genoa urban railway service, 3 lines)
 * Messina, 1 line
 * Milan (Milan suburban railway service, 12 lines)
 * Naples, 8 lines
 * Palermo (Palermo metropolitan railway service, 2 lines)
 * Perugia, 1 line
 * Potenza, 1 line
 * Reggio Calabria, 1 line
 * Rome (FL lines, 8 lines)
 * Salerno (Salerno metropolitan railway service, 1 line)
 * Turin (Turin metropolitan railway service, 8 lines)

Randstadspoor is a network of Sprinter train services in and around the city of Utrecht in the Netherlands. For the realisation of this network, new stations were opened. Separate tracks have been built for these trains, so they can call frequently without disturbing high-frequent Intercity services parallel to these routes. Similar systems are planned for The Hague and Rotterdam.

Northern Europe
In Sweden, electrified commuter rail systems known as Pendeltåg are present in the cities of Stockholm and Gothenburg. The Stockholm commuter rail system, which began in 1968, shares railway tracks with inter-city trains and freight trains, but for the most part runs on its own dedicated tracks. It is primarily used to transport passengers from nearby towns and other suburban areas into the city centre, not for transportation inside the city centre. The Gothenburg commuter rail system, which began in 1960, is similar to the Stockholm system, but does fully share tracks with long-distance trains.

In Norway, the Oslo commuter rail system mostly shares tracks with more long-distance trains, but also runs on some local railways without other traffic. Services converge on a primary main line between Asker and Lillestrøm. Oslo has the largest commuter rail system in the Nordic countries in terms of line lengths and number of stations. But some lines have travel times (over an hour from Oslo) and frequencies (once per hour) which are more like regional trains. Also Bergen, Stavanger and Trondheim have commuter rail systems. These have only one or two lines each and they share tracks with other trains.

In Finland, the Helsinki commuter rail network runs on dedicated tracks from Helsinki Central railway station to Leppävaara and Kerava. The Ring Rail Line serves Helsinki Airport and northern suburbs of Vantaa and is exclusively used by the commuter rail network. On 15 December 2019, the Tampere region got its own commuter rail service, with trains running from Tampere to Nokia, Lempäälä and Orivesi.

Southern Europe
In Spain, Cercanías networks exist in Madrid, Sevilla, Murcia/Alicante, San Sebastián, Cádiz, Valencia, Asturias, Santander, Zaragoza, Bilbao and Málaga. All these systems include underground sections in the city centre. There is also a network of narrow-gauge commuter systems in North Spain and Murcia. Cercanías Madrid is one of the most important train services in the country, more than 900,000 passengers move in the system. It has underground stations in Madrid like Recoletos, Sol or Nuevos Ministerios and in the metropolitan area in cities like Parla or Getafe.

In the autonomous community of Catalonia, and unlike the rest of Spain, the commuter service is not managed by Renfe Operadora. Since 2010, the Government of Catalonia has managed all the regular commuter services with the "transfer of Rodalies". There are two companies that manage the Catalan commuter network:

 * Rodalies de Catalunya, which after the transfer at the beginning of 2010 when, due to the "Catalan rail chaos" of 2007, the Spanish government promised to transfer the Renfe commuter service to the Generalitat, although it does not deal with the entire service; After the transfer, responsibilities for the commuter trains were divided into three parts: the Generalitat (management, regulation, planning, coordination and inspection of services and activities and power to charge), Renfe (train operator and its maintenance), and Adif (owner of the railway infrastructure). Lines R1, R2, R2 Nord, R2 Sud, R3 (to Sant Quirze de Besora, from there to Puigcerdà or La Tor de Querol it is considered a regional route), R4, R7 and R8 run through Rodalies de Catalunya, all on Iberian gauge (1668 mm).

The Government of Catalonia will assume full control of the current R12 regional line in 2024 and it will be owned by the FGC. It will eliminate the current line and replace it with the new commuter lines RL3 and RL4, towards Cervera and Manresa from Lleida respectively.
 * Ferrocarrils de la Generalitat de Catalunya (or FGC) is the railway company responsible for the Vallès, Llobregat-Anoia and Lleida-La Pobla de Segur lines. This company is mainly in charge of metro and suburban lines, although it also has five commuter lines spread over two lines, four on the Llobregat-Anoia line (R5, R50, R6, R60) on metre-gauge (1000 mm) and a single line on the Lleida-La Pobla de Segur line (RL1) on Iberian gauge (1668 mm). FGC is in charge of the entire service, unlike Rodalies de Catalunya, which is not in charge of either the trains or the infrastructure.

In Italy there are several commuter rail networks:
 * Roman FL lines cover most of the Latium regional railways.
 * Milan suburban railway service, operated by Trenord, has numerous services funneling into the underground Milan Passante railway.
 * Turin metropolitan railway service, operated by Trenitalia and GTT, with an underground railway line running through the city used by most services.
 * Naples Metro Line 2 is an underground corridor where commuter rail services operated by Trenitalia traverse and service the urban center.
 * Genoa urban railway service consists in three lines passing through the Giovi railway line and the Tyrrhenian railway lines Genoa–Ventimiglia and Genoa–Pisa.
 * Bologna metropolitan railway service. The system comprises 8 lines.
 * Bari metropolitan railway service
 * Canton Tessin suburban railway reaches Italian cities like Como and Varese and the Malpensa Airport.

Eastern Europe
In Poland, commuter rail systems exist in Tricity, Warsaw, Kraków (SKA) and Katowice (SKR). There is also a similar system planned in Wrocław and Szczecin. The terms used are "Szybka Kolej Miejska" (fast urban rail) and "kolej aglomeracyjna" (agglomeration rail). These systems are:
 * Szybka Kolej Miejska w Warszawie in the Warsaw urban area, with 4 lines and 46 stations.
 * Łódzka Kolej Aglomeracyjna is located in the center of Poland connecting satellite towns in and around Łódź. It also operates some trains between Łódź and Warsaw.
 * Szybka Kolej Miejska w Trójmieście is located in the Tricity/Trójmiasto urban area, the three cities of Gdańsk, Gdynia and Sopot.

The Proastiakos (Προαστιακός; "suburban") is Greece's suburban railway (commuter rail) services, which are run by TrainOSE, on infrastructure owned by the Hellenic Railways Organisation (OSE). There are three Proastiakos networks, servicing the country's three largest cities: Athens, Thessaloniki and Patras. In particular, the Athenian network is undergoing modifications to completely separate it from mainline traffic, by re-routing the tracks via a tunnel underneath the city center. A similar project is planned for the Patras network, whereas a new line is due to be constructed for the Thessalonian network.

In Romania, the first commuter trains were introduced in December 2019. They operate between Bucharest and Funduea or Buftea.

BG Voz is an urban rail system that serves Belgrade. It currently has only two routes, with plans for further expansion. Between early 1990s and mid-2010s, there was another system, known as Beovoz, that was used to provide mass-transit service within the Belgrade metropolitan area, as well as to nearby towns, similarly to RER in Paris. Beovoz had more lines and far more stops than the current system. However, it was abandoned in favor of more accurate BG Voz, mostly due to inefficiency. While current services rely mostly on the existing infrastructure, any further development means furthering capacities (railways expansion and new trains). Plans for further extension of system include another two lines, one of which should reach Belgrade Nikola Tesla Airport.

In Russia, Ukraine and some other countries of the former Soviet Union, electrical multiple unit passenger suburban trains called Elektrichka are widespread. The first such system in Russia is the Oranienbaum Electric Line in St. Petersburg. In Moscow the Beskudnikovskaya railway branch existed between the 1940s and 1980s. The trains that shuttled along it did not go to the main lines, so it was a city transport. Today there are the Moscow Central Circle and the Moscow Central Diameters.

In Turkey, Marmaray line stations from Sirkeci to Halkalı are located at the European side.

North America
In the United States, Canada, Costa Rica, El Salvador and Mexico regional passenger rail services are provided by governmental or quasi-governmental agencies, with the busiest and most expansive rail networks located in the Northeastern US, California, and Eastern Canada. Most North American commuter railways utilize diesel locomotive propulsion, with the exception of services in New York City, Philadelphia, Chicago, Denver, and Mexico City; New York's commuter rail lines use a combination of third rail and overhead wire power generation, while Chicago only has two out of twelve services that are electrified. Many newer and proposed systems in Canada and the United States are often are geared to serving peak-hour commutes as opposed to the all-day systems of Europe, East Asia, and Australia.

United States
Eight commuter rail systems in the United States carried over ten million trips each in 2018, those being in descending order:

 * Metropolitan Transportation Authority's Long Island Rail Road, serving New York City and Long Island
 * NJ Transit Rail Operations, serving New York City, New Jersey (Newark, Trenton) and Philadelphia
 * Metropolitan Transportation Authority's Metro-North Railroad, serving New York (Yonkers and New York City) and Southwest Connecticut (New Haven)
 * Metra, serving northeast Illinois (Chicago) and Kenosha, Wisconsin. The network consists of 11 services, of which only the Electric District service runs on tracks exclusively used for passenger traffic.
 * The South Shore Line is a commuter line that serves the South Side and northern Indiana. Although the line is operated by NICTD, an agency separate from Metra, the line runs along the Metra Electric Line north of Kensington/115th Street station.
 * SEPTA Regional Rail, serving southeast Pennsylvania (Philadelphia), as well as Wilmington, Delaware, and Trenton, New Jersey. The network features a tunneled corridor through the city center and through-routed services from several commuter lines. The arrangement of services through the corridor was originally proposed by Vukan Vuchic and Shinya Kikuchi in 1984 and 1985.
 * MBTA Commuter Rail, serving Massachusetts (Boston, Worcester, Lowell) and Providence, Rhode Island
 * Caltrain, serving California (San Francisco, San Jose, and the San Francisco Peninsula)
 * Metrolink, serving California (Los Angeles, Burbank, Anaheim, San Bernardino, and Southern California)

Other commuter rail systems in the United States (not in ridership order) are:

 * CTRail, serving Connecticut (Hartford, New Haven and New London)
 * Utah Transit Authority FrontRunner, serving Utah (Wasatch Front)
 * North County Transit District Coaster, serving California (San Diego County)
 * Maryland Area Regional Commuter, serving Maryland (Baltimore) and Washington, D.C.
 * Regional Transportation District, serving Colorado (Denver)
 * Virginia Railway Express, serving suburbs of Northern Virginia and Washington, D.C.
 * Sounder commuter rail, serving Washington (Seattle / Tacoma)
 * Tri-Rail, serving Florida (Miami / Fort Lauderdale / West Palm Beach)
 * Trinity Railway Express, serving Texas (Dallas / Fort Worth)
 * Westside Express Service, serving Oregon (Beaverton / Wilsonville)
 * Altamont Corridor Express, serving California (San Jose / Stockton)
 * SunRail, serving Florida (Orlando/Poinciana)
 * New Mexico Rail Runner Express, serving New Mexico (Albuquerque)
 * Northstar Line, serving Minnesota (Big Lake and downtown Minneapolis)
 * Capital MetroRail, serving Texas (Austin)
 * A-train, serving Texas (Denton County)
 * SMART, serving California (Sonoma and Marin counties)
 * WeGo Star, serving Nashville and Lebanon, Tennessee.
 * Denver's RTD four electrified commuter rail lines – the A, B, G and N Lines, run on segregated tracks. In its entirety the system combines elements of tram-train and commuter rail.

Canada

 * Exo in Montreal
 * GO Transit in Toronto
 * West Coast Express in Vancouver
 * UP Express in Toronto

Mexico

 * Suburban Railway of the Valley of Mexico Metropolitan Area serving Mexico City
 * Toluca–Mexico City commuter rail serving Toluca and Mexico City

Central America

 * Rail Transport in Costa Rica serving San Jose

South America
Examples include an 899 km commuter system in the Buenos Aires metropolitan area, the 225 km long Supervia in Rio de Janeiro, the Metrotrén in Santiago, Chile, and the Valparaíso Metro in Valparaíso, Chile.

Another example is Companhia Paulista de Trens Metropolitanos (CPTM) in Greater São Paulo, Brazil. CPTM has 94 stations with seven lines, numbered starting on 7 (the lines 1 to 6 and the line 15 belong to the São Paulo Metro), with a total length of 273 km. Trains operates at high frequencies on tracks used exclusively for commuter traffic. In Rio de Janeiro SuperVia provides electrified commuter rail services.

Oceania
The five major cities in Australia have suburban railway systems in their metropolitan areas. These networks have frequent services, with frequencies varying from every 10 to every 30 minutes on most suburban lines, and up to 3–5 minutes in peak on bundled underground lines in the city centres of Sydney, Brisbane, Perth and Melbourne. The networks in each state developed from mainline railways and have never been completely operationally separate from long distance and freight traffic, unlike metro systems. The suburban networks are almost completely electrified.

The main suburban rail networks in Australia are:
 * The Sydney Trains suburban rail network consists of nine lines converging in the underground City Circle with frequencies as high as three minutes in this section, 5–10 minutes at most major stations all day and 15 minutes at most minor stations all day.
 * The Sydney rail network operated by Sydney Trains in Sydney (with connected suburban services in Newcastle and Wollongong run by its counterpart intercity operator, NSW TrainLink).

 * Melbourne's rail network features sixteen electrified commuter rail lines traversing the city centre in the underground City Loop providing a metro-like service in the central core. A second underground core is under construction, as the Metro Tunnel project. V/Line operates some commuter services between Melbourne and surrounding towns, as well as between Melbourne and some locations within the Melbourne metropolitan area.

 * Commuter rail services in Brisbane are provided under the Queensland Rail City network brand, featuring twelve electrified lines converging in the city centre. Cross River Rail is an under construction underground cross-city tunnel to relieve pressure on this network.

 * Railways in Perth fall under the Transperth network, which are operated by the Public Transport Authority

 * The Adelaide rail network operated by Adelaide Metro in Adelaide.

New Zealand has two frequent suburban rail services comparable to those in Australia: the Auckland rail network is operated by Auckland One Rail and the Wellington rail network is operated by Transdev Wellington.

Hybrid systems
Hybrid urban-suburban rail systems exhibiting characteristics of both rapid transit and commuter rail serving a metropolitan region are common in German-speaking countries, where they are known as S-Bahn. Other examples include: Lazio regional railways in Rome, the RER in France and the Elizabeth line, London Underground Metropolitan line, London Overground and Merseyrail in the UK. Comparable systems can be found in Australia such as Sydney Trains and Metro Trains Melbourne, and in Japan with many urban and suburban lines operated by JR East/West and third-party companies running at metro-style frequencies. In contrast, comparable systems of this type are generally rare in the United States and Canada, where peak hour frequencies are more common.

In Asia, the construction of higher speed urban-suburban rail links has gained traction in various countries, such as in India, with the Delhi RRTS, in China, with the Pearl River Delta Metropolitan Region intercity railway, and in South Korea, with the Great Train eXpress system. These systems usually run on dedicated elevated or underground tracks for most of their route and have features comparable to Higher-speed rail.

title: Commuter rail


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Cambridgeshire

Cambridgeshire (abbreviated Cambs.) is a ceremonial county in the East of England and East Anglia. It is bordered by Lincolnshire to the north, Norfolk to the north-east, Suffolk to the east, Essex and Hertfordshire to the south, and Bedfordshire and Northamptonshire to the west. The largest settlement is the city of Peterborough, and the city of Cambridge is the county town.

The county has an area of 3389 km2 and a population of 852,523. Peterborough and Cambridge, located in the north-west and south respectively, are by far the largest settlements. The remainder of the county is rural, and contains the city of Ely, and towns such as Wisbech and St Neots.

For local government purposes, Cambridgeshire comprises a non-metropolitan county, with five districts, and the unitary authority area of Peterborough. The local authorities collaborate through Cambridgeshire and Peterbrough Combined Authority. The county did not historically include Huntingdonshire or the Soke of Peterborough, which was part of Northamptonshire.

The north and east of the county are dominated by the Fens, an extremely flat, drained marsh maintained by drainage ditches and dykes. Holme Fen is the UK's lowest physical point, at 2.75 m (9 ft) below sea level. The flatness of the landscape makes the few areas of higher ground, such as that Ely is built on, very conspicuous. The landscape in the south and west is gently undulating. Cambridgeshire's principal rivers are the Nene, which flows through the north of the county and is canalised east of Peterborough; the Great Ouse, which flows from west to east past Huntingdon and Ely; and the Cam, a tributary of the Great Ouse which flows through Cambridge.

History
Cambridgeshire is noted as the site of Flag Fen in Fengate, one of the earliest-known Neolithic permanent settlements in the United Kingdom, compared in importance to Balbridie in Aberdeen, Scotland. Must Farm quarry, at Whittlesey, has been described as "Britain's Pompeii due to its relatively good condition, including the 'best-preserved Bronze Age dwellings ever found in the UK'". A great quantity of archaeological finds from the Stone Age, the Bronze Age, and the Iron Age were made in East Cambridgeshire. Most items were found in Isleham.

The area was settled by the Anglo-Saxons starting in the fifth century. Genetic testing on seven skeletons found in Anglo-Saxon era graves in Hinxton and Oakington found that five were either migrants or descended from migrants from the continent, one was a native Briton, and one had both continental and native ancestry, suggesting intermarriage.

Cambridgeshire was recorded in the Domesday Book as "Grantbridgeshire" (or rather Grentebrigescire) (related to the river Granta). Covering a large part of East Anglia, Cambridgeshire today is the result of several local government unifications. In 1888 when county councils were introduced, separate councils were set up, following the traditional division of Cambridgeshire, for In 1965, these two administrative counties were merged to form Cambridgeshire and the Isle of Ely. Under the Local Government Act 1972 this merged with the county to the west, Huntingdon and Peterborough, which had been formed in 1965, by the merger of Huntingdonshire with the Soke of Peterborough (the latter previously a part of Northamptonshire with its own county council). The resulting county was called simply Cambridgeshire.
 * the area in the south around Cambridge, and
 * the liberty of the Isle of Ely.

Since 1998, the City of Peterborough has been separately administered as a unitary authority area. It is associated with Cambridgeshire for ceremonial purposes such as Lieutenancy and joint functions such as policing and the fire service.

In 2002, the conservation charity Plantlife unofficially designated Cambridgeshire's county flower as the Pasqueflower.

The Cambridgeshire Regiment (nicknamed the Fen Tigers), the county-based army unit, fought in the Boer War in South Africa, the First World War and Second World War.

Due to the county's flat terrain and proximity to the continent, during the Second World War the military built many airfields here for RAF Bomber Command, RAF Fighter Command, and the allies USAAF. In recognition of this collaboration, the Cambridge American Cemetery and Memorial is located in Madingley. It is the only WWII burial ground in England for American servicemen who died during that event.

Most English counties have nicknames for their people, such as a "Tyke" from Yorkshire and a "Yellowbelly" from Lincolnshire. The historical nicknames for people from Cambridgeshire are "Cambridgeshire Camel" or "Cambridgeshire Crane", the latter referring to the wildfowl that were once abundant in the Fens. The term "Fen Tigers" is sometimes used to describe the people who live and work in the Fens.

Original historical documents relating to Cambridgeshire are held by Cambridgeshire Archives. Cambridgeshire County Council Libraries maintains several Local Studies collections of printed and published materials, significantly at the Cambridgeshire Collection held in the Cambridge Central Library.

Flag
Cambridgeshire's county flag was made official on 1 February 2015, after the design was selected as an entry from a design competition that ran during 2014. The design features three golden crowns, two on the top, one on the bottom that are separated by two wavy lines in the middle. The crowns are meant to represent East Anglia, and the two lines represent the River Cam and are in the Cambridge University's colours.

Geography

 * See also Geology of Cambridgeshire

Large areas of the county are extremely low-lying and Holme Fen is notable for being the UK's lowest physical point at 2.75 m (9 ft) below sea level. The highest point of the modern administrative county is in the village of Great Chishill at 146 m (480 ft) above sea level. However, this parish was historically a part of Essex, having been moved to Cambridgeshire in boundary changes in 1895. The historic county top is close to the village of Castle Camps where a point on the disused RAF airfield reaches a height of 128 metre above sea level (grid reference TL 63282 41881).

Other prominent hills are Little Trees Hill and Wandlebury Hill (both at 74 m) in the Gog Magog Hills, Rivey Hill above Linton, Rowley's Hill and the Madingley Hills.

Wicken Fen is a 254.5 hectare biological Site of Special Scientific Interest west of Wicken. A large part of it is owned and managed by the National Trust.

Green belt
Cambridgeshire contains all its green belt around the city of Cambridge, extending to places such as Waterbeach, Lode, Duxford, Little & Great Abington and other communities a few miles away in nearby districts, to afford a protection from the conurbation. It was first drawn up in the 1950s.

Politics
Cambridgeshire County Council is controlled by an alliance of the Liberal Democrats, the Labour Party and independent groups, while Peterborough City Council is currently controlled by a Conservative Party minority administration.

The county contains seven Parliamentary constituencies:

Economy
This is a chart of trend of regional gross value added of Cambridgeshire at current basic prices published (pp. 240–253) by Office for National Statistics with figures in millions of English Pounds Sterling.

AWG plc is based in Huntingdon. The RAF has several stations in the Huntingdon and St Ives area. RAF Alconbury, three miles north of Huntingdon, is being reorganised after a period of obsolescence following the departure of the USAF, to be the focus of RAF/USAFE intelligence operations, with activities at Upwood and Molesworth being transferred there. Most of Cambridgeshire is agricultural. Close to Cambridge is the so-called Silicon Fen area of high-technology (electronics, computing and biotechnology) companies. ARM Limited is based in Cherry Hinton. The inland Port of Wisbech on the River Nene is the county's only remaining port.

Primary and secondary
Cambridgeshire has a comprehensive education system with over 240 state schools, not including sixth form colleges. The independent sector includes King's Ely and Wisbech Grammar School, founded in 970 and 1379 respectively, they are two of the oldest schools in the country.

Some of the secondary schools act as Village Colleges, institutions unique to Cambridgeshire. For example, Comberton Village College.

Tertiary
Cambridgeshire is home to a number of institutes of higher education:

 * The University of Cambridge – second-oldest university in the English-speaking world, and regarded as one of the most prestigious academic institutions in the world
 * Anglia Ruskin University – has campuses located in Cambridge and Peterborough and a base at Fulbourn
 * The Open University – has a regional centre located in Cambridge
 * The University Centre Peterborough – operated by Anglia Ruskin University and Peterborough Regional College, located in Peterborough
 * The College of West Anglia has a campus at Milton, on the northern outskirts of Cambridge and a campus at Wisbech.

In addition, Cambridge Regional College and Huntingdonshire Regional College both offer a limited range of higher education courses in conjunction with partner universities.

Settlements

These are the settlements in Cambridgeshire with a town charter, city status or a population over 5,000; for a complete list of settlements see list of places in Cambridgeshire.
 * Burwell
 * Cambridge
 * Chatteris
 * Cottenham
 * Ely
 * Godmanchester
 * Huntingdon
 * Littleport
 * March
 * Peterborough
 * Ramsey
 * Sawston
 * Sawtry
 * Soham
 * St Ives
 * St Neots
 * Wisbech
 * Whittlesey
 * Yaxley

See the List of Cambridgeshire settlements by population page for more detail.

The town of Newmarket is surrounded on three sides by Cambridgeshire, being connected by a narrow strip of land to the rest of Suffolk.

Cambridgeshire has seen 32,869 dwellings created from 2002 to 2013 and there are a further 35,360 planned new dwellings between 2016 and 2023.

Climate
Cambridgeshire has a maritime temperate climate which is broadly similar to the rest of the United Kingdom, though it is drier than the UK average due to its low altitude and easterly location, the prevailing southwesterly winds having already deposited moisture on higher ground further west. Average winter temperatures are cooler than the English average, due to Cambridgeshire's inland location and relative nearness to continental Europe, which results in the moderating maritime influence being less strong. Snowfall is slightly more common than in western areas, due to the relative winter coolness and easterly winds bringing occasional snow from the North Sea. In summer temperatures are average or slightly above, due to less cloud cover. It reaches 25 °C on around ten days each year, and is comparable to parts of Kent and East Anglia.

Sports
Various forms of football have been popular in Cambridgeshire since medieval times at least. In 1579 one match played at Chesterton between townspeople and University of Cambridge students ended in a violent brawl that led the Vice-Chancellor to issue a decree forbidding them to play "footeball" outside of college grounds. During the nineteenth century, several formulations of the laws of football, known as the Cambridge rules, were created by students at the university. One of these codes, dating from 1863, had a significant influence on the creation of the original laws of the Football Association.

Cambridgeshire is also the birthplace of bandy, now an IOC accepted sport. According to documents from 1813, Bury Fen Bandy Club was undefeated for 100 years. A member of the club, Charles Goodman Tebbutt, wrote down the first official rules in 1882. Tebbutt was instrumental in spreading the sport to many countries. Great Britain Bandy Association is based in Cambridgeshire.

Fen skating is a traditional form of skating in the Fenland. The National Ice Skating Association was set up in Cambridge in 1879, they took the top Fen skaters to the world speedskating championships where James Smart (skater) became world champion.

On 6–7 June 2015, the inaugural Tour of Cambridgeshire cycle race took place on closed roads across the county. The event was an official UCI qualification event, and consisted of a Time Trial on the 6th, and a Gran Fondo event on the 7th. The Gran Fondo event was open to the public, and over 6000 riders took part in the 128 km race.

The River Cam is the main river flowing through Cambridge, parts of the River Nene and River Great Ouse lie within the county. In 2021 the latter was used as the course for The Boat Race. The River Cam serves as the course for the university Lent Bumps and May Bumps and the non-college rowing organised by Cambridgeshire Rowing Association.

There is only one racecourse in Cambridgeshire, located at Huntingdon.

Contemporary art
Cambridge is home to the Kettle's Yard gallery and the artist-run Aid and Abet project space. Nine miles west of Cambridge next to the village of Bourn is Wysing Arts Centre. Wisbech has been home to the Wisbech Gallery, South Brink since 2023. Cambridge Open Studios is the region's large arts organisation with over 500 members. Every year, more than 370 artists open their doors to visitors during four weekends in July.

Literature
The annual Fenland Poet Laureate awards were instigated for poets in the North of the county in 2012 at Wisbech & Fenland Museum.

Theatre
The county was visited by travelling companies of comedians in the Georgian period. These came from different companies. The Lincoln Circuit included, at various times, Wisbech and Whittlesey. The Wisbech Georgian theatre still survives as an operating theatre now known as The Angles Theatre. In Cambridge the ADC Theatre is the venue for the Footlights.

Television
The county is covered by BBC East and ITV Anglia which broadcast from Norwich. Television signals are received from the Sandy Heath TV transmitter.

Radio
BBC Local Radio for the county is served by BBC Radio Cambridgeshire which broadcasts from its studio in Cambridge. County-wide commercial radio stations are Heart East, Greatest Hits Radio East, Star Radio, Cambridge 105, Connect FM (covering Peterborough), and HCR FM (for Huntingdonshire).

Places of interest
• Angles Theatre

• Anglesey Abbey NTE icon.svg AP Icon.svg

• Brampton Wood

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• Cambridge American Cemetery and Memorial

• Cambridge University Museum of Zoology

• Castor Hanglands NNR

• Cherry Hinton Chalk Pits

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• Devil's Dyke

• Down Field Windmill

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• Fitzwilliam Museum, Cambridge

• Flag Fen

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• Great Gransden Post Mill

• Hereward Way

• Hinchingbrooke House HH icon.svg

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• Kettle's Yard

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• King's College, Cambridge

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• University of Cambridge Museum of Archaeology and Anthropology

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• Wisbech & Fenland Museum

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• WWT Welney

• Wysing Arts Centre

Notable people from Cambridgeshire

 * Oliver Cromwell (1599–1658), Roundhead commander in the English Civil War from 1642 to 1651, and Lord Protector of the Commonwealth of England, Scotland and Ireland from 1653 to 1658

title: Cambridgeshire


text:
Talk:Computational linguistics

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Untitled
If you folks don't mind, I'm going to make some changes to the Origins section of this article some time in the next week. I'm going to add some material about the work of David G. Hays. He led the machine translation effort at RAND back in the 50s and 60s, was one of the authors of the ALPAC report, wrote the first textbook in computational linguistics, was instrumental in founding the Association for Computational Linguistics, and the International Committee on Computational Linguistics, was the first editor of the ACL's journal and so forth. I'll be adding an article about Hays himself, then I'll link it to this article, and, as I said, make a some changes to the history section.

AI is is generally considered to have originated in 1956 with a conference at Dartmouth, where the term "artificial intelligence" was coined. MT was under-way before that time. When MT morphed into CL during the mid-60s it maintained a somewhat separate identity from AI and, so far as I know, does to this day. AI, CL, and NLP are closely related, obviously, and some researchers may consider themselves to be two or three of those, or only one. Bill 21:22, 16 March 2006 (UTC)

Merge with NLP?
Judging from the discussions, there doesn't seem to emerge a consensus on whether or not this article should be merged with Natural Language Processing. I think they should be merged since So I vote for a merge. Kallerdis (talk) 20:06, 29 February 2008 (UTC)
 * Although it might be historically justified to speak about a division, this is meaningless as the fields stands today. Whether you call it NLP or CL is today arbitrary and mostly a question of what aspect you stress.
 * Current articles in the Computational Linguistics journal, and at the Coling and ACL conferences, are judged on whether they are useful rather than on whether they give any insight on how humans process language.
 * Most of the material in this article belongs in the NLP article anyway.
 * We can't seem to come up with a definition of CL, and where to draw the line between the two "fields".

Dear All,

I am painfully aware of the many names used for this area (CL, NLP, Language Engineering, Human Language Technology, Language Technology, ...). Many of these terms denote nearly identical areas, but not all. My experience is that, in many countries, one uses two separate concepts, one narrow and one broad:

 * 1) The narrow one being defined (as also cited below by others) as a study of language using the methods and inspiration from computer science.  This definition puts much weight on the automatic parsing, especially using linguistically motivated grammar models.
 * 2) The broad concept includes the narrow one as its core, but also includes much material from the areas where the core methods can be applied.  It is also common that speech technology is included as a part of the broad area.

I would not be alone in proposing that, in the Wikipedia, we would establish two concepts (=articles) one for the narrow one and use the title computational linguistics for it, and another with title language technology (or human language technology). Both could have an account of the possible synonyms or alternative terms. The distinction is, anyway present in many languages other than English (Finnish 'tietokonelingvistiikka' vs. 'kieliteknologia', Swedish, Danish and Norwegian roughly 'datalingvistik' vs. 'språkteknologi').

Together with some colleagues, we would like to use Wikipedia as a platform for creating consistent multilingual terminologies for CL/LT. This would be feasible if there are consistent concepts which can be linked between languages.

-- Kimmo Koskenniemi, prof. of computational linguistic (but teaching language technology) --

HI....

I'm a student at a computational linguistics department (CoLi at Saarbruecken), and I have been a (visiting) student at a natural language processing department (HCRC at Edinburgh). I think each might have been close to being the biggest in the world in their respective "fields". But honestly, I can't tell the difference!!!

I think the key is: how are the terms commonly used? Once, (while I was stationed at Edinburgh but making a weekend trip to Cambridge), a Cambridge prof came up to me and said, "So, you're from Edinburgh, I bet you do NLP." Yes, I replied, not wanting to get into the details about really being from CoLi at Saarbruecken. "Heh," he says, "NLP is totally unfounded. At Cambridge, we do computational linguistics." Now (for those of us who are not irony impared ;) I think this is pretty strong evidence that the terms are used as synonyms within the field. And if they are used as synonyms within the field, then what exactly is this page describing?

PS... with the ACL quote... I think it might be decades old. If there is an "engineering/science" distinction between NLP and CL, then the ACL quote has got to be ironic because most of the research in their journal and at their conferences is clearly engineering.

-- pobody

I don't disagree that Natural Language Processing is useful and important. I'm just not convinced that Computational Linguistics is the same thing as Natural Language Processing.

According to the The Association for Computational Linguistics web page defining Computational Linguistics, ( http://www.aclweb.org/archive/what.html ) the definition is broader than appears on this page: ''computational linguistics is the scientific study of language from a computational perspective. Computational linguists are interested in providing computational models of various kinds of linguistic phenomena.''

i'm changing the article heavily and splitting large portions off into [Natural Language Processing] to reflect the fact that these two fields are related, but not at all the same thing. --jkominek

Well, but I do not think that NLP and CL do not overlap, I think they have a lot in common. At my university we do mostly NLP in computational linguistics. In the first year, there are the foundations (theoretical linguistics, computer science, logic, relations, trees, grammars), and the second year class is called "Natural language processing systems". According to the professor, computational linguistics IS about designing natural language processing systems. But I do not have anything written on my desk here (will deliver this later, ok?). I must also admit that he was CS prof before, so he may be biased ;-). Of course it is ok to have a separate entry, as CL and NLP are not synonyms.

I recommend to delete the sentence "... which is in the domain of computer science", as this implies NLP does not belong to CL. Instead, I would write "An important task of CL _is_ NLP" or sth. similar.

I also do not agree that CL is (only) a subfield of linguistics, as it is an interdisciplinary field, somewhere in between theoretical CS/maths, applied computer science, AI, and linguistics.

As I am new here, and still want to think about, I do not make changes immediatly (I also do not have the time atm to build proper, good-looking sentences, as I am at work).

Best regards,

-- zeno

Computational linguistics is the original term for the field of language processing that developed following the collapse of MT with the ALPAC report in the 1960s. Originally, it was thought that computers could perform translation of language quite easily, whereas in fact its exactly the opposite. I would characterize the difference between computational linguistics and natural language processing as the difference between computer science and software development, i.e., between the theoretical and the practical. Some computational linguists are not really interested in natural language processing and prefer to work exclusively on theoretical problems, whereas others are actual practitioners of the field--same as in computer science.

Also the assumption that computational linguists are linguists is wrong. Computational linguists came into the field from a variety of disciplines including mathematics, computer science and psychology. Computational linguistics predates AI. It is a separate and parallel field of those concerned with having computers process language in any way. It's major subfields include: speech generation, speech recognition, parsing theory, text generation and of course its original impetus, mechanical (or machine) translation.

Whereas today I expect you can easily study computational linguistics in a linguistics department, in the 1970s and early 1980s this was rare.

Dr. Robert A. Amsler, Sr. Computational Linguist, SEA/DOE

Computational linguistics would seem to involve more statistical (pattern recognition, markov, etc.) and NLP more determining parts of speech and trying to get meaning. Wouldn't it? User:KellyCoinGuy

 * No. both are used/covered by both "fields". --zeno 00:37, 21 Dec 2004 (UTC)
 * According to the Handbook of Computational Linguistics (2007), "Computational Linguistics" is used when a substantial amount of linguistic knowledge is incorporated into the computational model whereas "natural language processing" usually refers to a mainly stochastic language modeling. --Tomonori 03:31, 1 August 2007 (UTC)

I had it explained to me something like as follows:

 * Computational linguistics is where we make programs that should work, but don't and we don't know why
 * Natural language processing is where we make programs that shouldn't work, but do and we don't know why

- Francis Tyers · 14:36, 28 February 2009 (UTC)

 * Heh, that rings true to me. I studied cog sci at Yale in the late 1980s including some AI. Both terms are familiar to me and somewhat interchangeable. There were some folks using computers to analyze speech not as I/O for software, but in order to understand language as a psycholinguistic and physiological phenomenon; for these folks I would have used the term computational linguistics and not natural language processing. But that is only a useful distinction, to the extent that we want to draw a line between "computational linguistics" and "non-computational linguistics"—and I would argue that today computers are so omnipresent that the distinction is mostly historical.
 * I draw a parallel to 3D graphics. Prior to 1993, the term mostly referred to ugly green simulations created in DoD-funded university CS departments, and academic papers on more photorealistic stuff that was supposed to be decades away. Then almost overnight, the term got a new meaning: first-person shooter games like Marathon and Doom. SIGGRAPH never had a problem with disambiguation; it was all just "graphics".
 * A few years later, natural language leaped similarly from academic to practical, with interactive voice response (IVR) and machine translation. But we never settled on a generic word like graphics to cover it all. So I'm leaning toward a merge into "natural language processing" at the minor cost of some historical nuance. Whatever we choose, can somebody (who's more current on this stuff than I am) please find a supporting citation that asserts the breadth of the term?
 * Mrevan (talk) 11:07, 13 April 2009 (UTC)

It seems to me that the state of things is that the boundary between NLP and CL is unclear. I think the goal of any related Wikipedia articles should be to represent the state of things as accurately as possible, NOT to solve the clarity problem. Thus, both articles should clearly :) state that various opinions about these fields. Indquimal (talk) 22:06, 18 May 2009 (UTC)

As has been stated, CL and NLP have different origins and different goals - one to understand human language, one to produce more effective computer interfaces and deal with the problems natural languages serve up. At the moment, certain paradigms are dominant in NLP and carry over to CL, swamping techniques that come out of Linguistics, and this reflects the number of people coming in to the combined area from the AI and Lg sides. But most NLP does little to advance the aims of CL, and there are relatively few development that both advance CL and deliver improvements in NLP performaance - but these are ones we should pay particular attention to. — Preceding unsigned comment added by Dmwpowers (talk • contribs) 03:49, 25 August 2012 (UTC)

To my mind these are absolutely different--but I don't disagree that the boundaries are blurry and that a dept. doing NLP, say, would likely be comfortable for someone who identifies as a CL. Keep separate and work on the defns. JJL (talk) 02:36, 26 August 2012 (UTC)

Computational Historical Linguistics
In the last decade computational methods have been applied to historical linguistics. This article does not cover this aspect. Really a separate article is required with a change to the title of this one to separate it. Adresia (talk) 18:52, 29 November 2007 (UTC)
 * Sounds good. Do you have some sources? —Preceding unsigned comment added by Dranorter (talk • contribs) 03:48, 8 June 2009 (UTC)
 * This case points, imo, to the coming state of affairs: Linguistic research of various types will increasingly be presumed to use computing among its array of tools. We ought to be planning for, / gradually inching our way toward, the time when "Computational linguistics" will have become a term of mainly historical interest, and all branches of linguistics that are amenable to formal analysis of any kind will automatically be presumed to have a computational presence.--IfYouDoIfYouDon't (talk) 05:39, 19 September 2016 (UTC)

Stub template
Is there any stub template for use in articles related to computational linguistics? I haven't found any, but I think it would be viable, if it really didn't exist. -- Sandius 20:09, 7 February 2006 (UTC)

"Free online introductory book"?
As of this time, the external link Free online introductory book on Computational Linguistics has not responded at all for several hours. I have no way of knowing if this is temporary, but the link should be removed if this continues. 75.15.115.31 (talk) 08:21, 15 December 2008 (UTC)
 * Found it in the Internet Archive. --Thüringer ☼ (talk) 12:46, 15 December 2008 (UTC)
 * Seems to be working now. Dranorter (talk) 02:24, 8 June 2009 (UTC)

Humour
About the field. Sorry couldn't resist :) Note that the decision whether to merge being discussed above does kinda of support this... prat (talk) 00:56, 5 August 2010 (UTC)

Delete "Counter-views"
I would vote for deleting the "counter-views" section, marked out as of questionable quality. These don't represent well-known views in the field or fields close to it, and appears to take issue with "computational theories of language" rather than the field(s) of CL. I am more an observer than scholar of CL (though I have taught courses on it), & I don't think it's accurate to see it as promulgating a "theory" that needs to be balanced with "counter-views." Most CL just says that language can be productively analyzed using some computational tools or others, and justifies this assertion with actual research results. The "counter-view" would therefore be that no, computers aren't useful in linguistic analysis, a claim for which I know neither factual nor scholarly support. CL doesn't entail any statement about the nature of language per se (although some CL practitioners certainly do have such views), and this section obscures that. Wichitalineman (talk) 16:33, 2 February 2013 (UTC)

Dear Wichitalineman, The above discourse is an instance of intolerance, that leads to annihilation of dissenters' voice(s)and blocking of dialogue constitutive universals [Habermas]. I have few questions: (a)If computers or something x is a "tool" (as you said) for analyzing language or y-object, may we propose a full-fledged epistemological disciplinary technology, viz CL, depending on a "tool"? (b)Regarding your statement,"The "counter-view" would therefore be that no, computers aren't useful in linguistic analysis, a claim for which I know neither factual nor scholarly support", I must say that I do not know such extremist position that claims "computers aren't useful in linguistic analysis", but I know "factual"     and      "scholarly support" for anti-AI (both strong and weak)that is related to CL's epistemological status in relation to cognitivism. I have got this support from Roger Penrose's Godelian argument. — Preceding unsigned comment added by Debaprasad01 (talk • contribs) 20:39, 11 May 2015 (UTC)

Mathematical linguistics redirect
I don't think "Mathematical linguistics" should redirect to this page. If anything, "Math. Ling." is even more ill-defined, or more over-broad in use, than is the "Computational" term. The involvement of computer science in this putative subfield, under many of its apparent definitions, is at best secondary. (The mere suggestion that Mathematical ling. should redirect to Computational is reminiscent of the notion, still prevalent just a few years ago, that computing or computer programming was somehow "about" mathematics, or that a computer programmer was by definition a mathematician.)

Whoever created the redirect, I'll give you a short while to make restitution, no questions asked. Then the shaming shall begin. :~> (And no, I don't think I need to come up with a better place for "Mathematical linguistics" to (re)direct to. Redirecting here is inappropriate, in & of itself.) --IfYouDoIfYouDon't (talk) 05:09, 19 September 2016 (UTC)

New to Wikipedia editing
Hi all, I’m new to editing, and I’m also apart of a class that is taking a look at language in the digital age. I hope you all don’t mind if I attempt to improve my knowledge on the field by occasionally attempting to provide useful and pertinent information. Thank you Beardown25 (talk) 06:55, 10 September 2019 (UTC)

Approaches
At the moment, the Approaches section is very much essay-like, and less encyclopedia-style, and its prominent position in the article severely limits the usability of this page. (I guess this actually *was* an original essay, as it had been inserted as a single block.) I suggest to cut that down to 3-5 sentences per subsection, or, alternatively, rewrite from scratch, possibly taking an authoritative text book as a basis (not to copy from, but to follow its classifications). Chiarcos (talk) 08:39, 20 August 2020 (UTC)

On the Sindhi Language section
As of writing (12:10 pm EST, Mon Nov 9 2020), there is a paragraph in this article which reads:

In recent days, the structural data of languages is available for several languages of the world other than English language. Computational linguistics work is in progress on Sindhi language because the structure, grammar and domain of Sindhi language is different from the other languages of the World. The computational linguistics models for English language are not suitable for Sindhi language. Viewing this, computational linguistics work on Sindhi language [27][28][29] has been started properly by developing methods, algorithms, linguistics tools (https://sindhinlp.com/), machine learning models and deep learning models since 2016 [30][31][32][33][34][35] to focus and solve the linguistics problems of Sindhi language. This work could lead to further important discoveries regarding the underlying structure of Sindhi, and could have any number of effects on the understanding of Sindhi as a language.

I hope that this paragraph clearly presents itself as being nonfactual. I would be happy to offer sources to this if need be, but to state that the language spoken in one particular region of South Asia has "structure, grammar, and domain... different from the other languages of the World" is quite obviously unverifiable, and to me smells of the same sort of linguistic supremacy propaganda we see time and time again in pseudo-academia. Indeed, if we are to believe every article which states that some given language is somehow the most 'suitable' for computational analysis – Sanskrit, Hindustani, Sindhi, Macedonian – then the speakers of the rest of the (W)orld's languages ought to put some thought into why their languages, despite being equally qualified as a method of communication to every other language in the (W)orld, are so computer unfriendly, and/or why the great computational-linguistic minds of these locales have not made the incomparable advances in syntax parsing that we would expect with such an innate advantage.

173.35.233.148 (talk) 17:19, 9 November 2020 (UTC)

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title: Talk:Computational linguistics