Misplaced Pages

#341658

57-537: Land warfare is categorized by the use of large numbers of combat personnel employing a diverse set of combat skills, methods and a wide variety of weapon systems and equipment, conducted in diverse terrains and weather environments. Land warfare, by virtue of being conducted in defence of urban and rural population areas, dominates the study of war , and is a focus for most national defence policy planning and financial considerations. Land warfare in history has undergone several distinct transitions in conduct from

114-450: A UV completion , of the kind that string theory is intended to provide. In particular, superstring theory requires six compact dimensions (6D hyperspace) forming a Calabi–Yau manifold . Thus Kaluza-Klein theory may be considered either as an incomplete description on its own, or as a subset of string theory model building. In addition to small and curled up extra dimensions, there may be extra dimensions that instead are not apparent because

171-409: A dimension of two (2D) because two coordinates are needed to specify a point on it – for example, both a latitude and longitude are required to locate a point on the surface of a sphere. A two-dimensional Euclidean space is a two-dimensional space on the plane . The inside of a cube , a cylinder or a sphere is three-dimensional (3D) because three coordinates are needed to locate

228-417: A discrete set of points (such as a finite collection of points) to be 0-dimensional. By dragging a 0-dimensional object in some direction, one obtains a 1-dimensional object. By dragging a 1-dimensional object in a new direction , one obtains a 2-dimensional object. In general, one obtains an ( n + 1 )-dimensional object by dragging an n -dimensional object in a new direction. The inductive dimension of

285-414: A conceptual model of the cities as points, while giving directions involving travel "up," "down," or "along" a road imply a one-dimensional conceptual model. This is frequently done for purposes of data efficiency, visual simplicity, or cognitive efficiency, and is acceptable if the distinction between the representation and the represented is understood but can cause confusion if information users assume that

342-406: A large concentration of largely untrained and irregularly armed populace used in frontal assaults to current employment of combined arms concepts with highly trained regular troops using a wide variety of organisational, weapon and information systems, and employing a variety of strategic, operational and tactical doctrines. Although land combat in the past was conducted by the combat arms of

399-401: A line in only one direction (or its opposite); the dimension of a plane is two etc. The dimension is an intrinsic property of an object, in the sense that it is independent of the dimension of the space in which the object is or can be embedded. For example, a curve , such as a circle , is of dimension one, because the position of a point on a curve is determined by its signed distance along

456-416: A manifold depends on the base field with respect to which Euclidean space is defined. While analysis usually assumes a manifold to be over the real numbers , it is sometimes useful in the study of complex manifolds and algebraic varieties to work over the complex numbers instead. A complex number ( x + iy ) has a real part x and an imaginary part y , in which x and y are both real numbers; hence,

513-575: A particular space have the same cardinality . This cardinality is called the dimension of the Hilbert space. This dimension is finite if and only if the space's Hamel dimension is finite, and in this case the two dimensions coincide. Classical physics theories describe three physical dimensions : from a particular point in space , the basic directions in which we can move are up/down, left/right, and forward/backward. Movement in any other direction can be expressed in terms of just these three. Moving down

570-423: A point within these spaces. In classical mechanics , space and time are different categories and refer to absolute space and time . That conception of the world is a four-dimensional space but not the one that was found necessary to describe electromagnetism . The four dimensions (4D) of spacetime consist of events that are not absolutely defined spatially and temporally, but rather are known relative to

627-437: A regular grid", is essentially an indication of the ruggedness or relative height of the terrain. Geomorphology is in large part the study of the formation of terrain or topography. Terrain is formed by concurrent processes operating on the underlying geological structures over geological time : Tectonic processes such as orogenies and uplifts cause land to be elevated, whereas erosional and weathering processes wear

SECTION 10

#1732779782342

684-432: A representation of a real-world phenomenon may have a different (usually lower) dimension than the phenomenon being represented. For example, a city (a two-dimensional region) may be represented as a point, or a road (a three-dimensional volume of material) may be represented as a line. This dimensional generalization correlates with tendencies in spatial cognition. For example, asking the distance between two cities presumes

741-569: A terrain or curvatures at each location. These measures can also be used to derive hydrological parameters that reflect flow/erosion processes. Climatic parameters are based on the modelling of solar radiation or air flow. Land surface objects, or landforms , are definite physical objects (lines, points, areas) that differ from the surrounding objects. The most typical examples airlines of watersheds , stream patterns, ridges , break-lines , pools or borders of specific landforms. A digital elevation model (DEM) or digital surface model (DSM)

798-406: A topological space may refer to the small inductive dimension or the large inductive dimension , and is based on the analogy that, in the case of metric spaces, ( n + 1 )-dimensional balls have n -dimensional boundaries , permitting an inductive definition based on the dimension of the boundaries of open sets. Moreover, the boundary of a discrete set of points is the empty set, and therefore

855-608: Is a 3D computer graphics representation of elevation data to represent terrain or overlaying objects, commonly of a planet , moon , or asteroid . A "global DEM" refers to a discrete global grid . DEMs are used often in geographic information systems (GIS), and are the most common basis for digitally produced relief maps . A digital terrain model (DTM) represents specifically the ground surface while DEM and DSM may represent tree top canopy or building roofs. [REDACTED] The dictionary definition of terrain at Wiktionary Dimension In physics and mathematics ,

912-458: Is a dimension of time. Time is often referred to as the " fourth dimension " for this reason, but that is not to imply that it is a spatial dimension . A temporal dimension is one way to measure physical change. It is perceived differently from the three spatial dimensions in that there is only one of it, and that we cannot move freely in time but subjectively move in one direction . The equations used in physics to model reality do not treat time in

969-578: Is an algebraic group of dimension n acting on V , then the quotient stack [ V / G ] has dimension m  −  n . The Krull dimension of a commutative ring is the maximal length of chains of prime ideals in it, a chain of length n being a sequence P 0 ⊊ P 1 ⊊ ⋯ ⊊ P n {\displaystyle {\mathcal {P}}_{0}\subsetneq {\mathcal {P}}_{1}\subsetneq \cdots \subsetneq {\mathcal {P}}_{n}} of prime ideals related by inclusion. It

1026-422: Is an example of a four-dimensional object. Whereas outside mathematics the use of the term "dimension" is as in: "A tesseract has four dimensions ", mathematicians usually express this as: "The tesseract has dimension 4 ", or: "The dimension of the tesseract is 4" or: 4D. Although the notion of higher dimensions goes back to René Descartes , substantial development of a higher-dimensional geometry only began in

1083-480: Is an infinite-dimensional function space . The concept of dimension is not restricted to physical objects. High-dimensional space s frequently occur in mathematics and the sciences . They may be Euclidean spaces or more general parameter spaces or configuration spaces such as in Lagrangian or Hamiltonian mechanics ; these are abstract spaces , independent of the physical space . In mathematics ,

1140-491: Is available to support the existence of these extra dimensions. If hyperspace exists, it must be hidden from us by some physical mechanism. One well-studied possibility is that the extra dimensions may be "curled up" at such tiny scales as to be effectively invisible to current experiments. In 1921, Kaluza–Klein theory presented 5D including an extra dimension of space. At the level of quantum field theory , Kaluza–Klein theory unifies gravity with gauge interactions, based on

1197-420: Is critical for many reasons: Relief (or local relief ) refers specifically to the quantitative measurement of vertical elevation change in a landscape . It is the difference between maximum and minimum elevations within a given area, usually of limited extent. A relief can be described qualitatively, such as a " low relief " or " high relief " plain or upland . The relief of a landscape can change with

SECTION 20

#1732779782342

1254-403: Is probably the dimension of the tangent space at any Regular point of an algebraic variety . Another intuitive way is to define the dimension as the number of hyperplanes that are needed in order to have an intersection with the variety that is reduced to a finite number of points (dimension zero). This definition is based on the fact that the intersection of a variety with a hyperplane reduces

1311-416: Is said to be infinite, and one writes dim X = ∞ . Moreover, X has dimension −1, i.e. dim X = −1 if and only if X is empty. This definition of covering dimension can be extended from the class of normal spaces to all Tychonoff spaces merely by replacing the term "open" in the definition by the term " functionally open ". An inductive dimension may be defined inductively as follows. Consider

1368-460: Is strongly related to the dimension of an algebraic variety, because of the natural correspondence between sub-varieties and prime ideals of the ring of the polynomials on the variety. For an algebra over a field , the dimension as vector space is finite if and only if its Krull dimension is 0. For any normal topological space X , the Lebesgue covering dimension of X is defined to be

1425-475: Is the dimension and shape of a given surface of land . In physical geography , terrain is the lay of the land. This is usually expressed in terms of the elevation , slope , and orientation of terrain features. Terrain affects surface water flow and distribution. Over a large area, it can affect weather and climate patterns. Bathymetry is the study of underwater relief, while hypsometry studies terrain relative to sea level . The understanding of terrain

1482-680: Is the largest number of spatial dimensions in which strings can generically intersect. If initially there are many windings of strings around compact dimensions, space could only expand to macroscopic sizes once these windings are eliminated, which requires oppositely wound strings to find each other and annihilate. But strings can only find each other to annihilate at a meaningful rate in three dimensions, so it follows that only three dimensions of space are allowed to grow large given this kind of initial configuration. Extra dimensions are said to be universal if all fields are equally free to propagate within them. Several types of digital systems are based on

1539-410: Is the same as moving up a negative distance. Moving diagonally upward and forward is just as the name of the direction implies i.e. , moving in a linear combination of up and forward. In its simplest form: a line describes one dimension, a plane describes two dimensions, and a cube describes three dimensions. (See Space and Cartesian coordinate system .) A temporal dimension , or time dimension ,

1596-466: The armed forces , since World War II it has largely involved three distinct types of combat units: infantry , armour , and artillery . These arms, since the Age of Sail , have used amphibious warfare concepts and methods to project power from the seas and oceans , and since the wide introduction of military transport aircraft and helicopters have used airborne forces and vertical envelopment to

1653-592: The brane by their endpoints, whereas the closed strings that mediate the gravitational interaction are free to propagate into the whole spacetime, or "the bulk". This could be related to why gravity is exponentially weaker than the other forces, as it effectively dilutes itself as it propagates into a higher-dimensional volume. Some aspects of brane physics have been applied to cosmology . For example, brane gas cosmology attempts to explain why there are three dimensions of space using topological and thermodynamic considerations. According to this idea it would be since three

1710-399: The dimension of a mathematical space (or object ) is informally defined as the minimum number of coordinates needed to specify any point within it. Thus, a line has a dimension of one (1D) because only one coordinate is needed to specify a point on it – for example, the point at 5 on a number line. A surface , such as the boundary of a cylinder or sphere , has

1767-630: The force moving any object to change is time . In physics, three dimensions of space and one of time is the accepted norm. However, there are theories that attempt to unify the four fundamental forces by introducing extra dimensions / hyperspace . Most notably, superstring theory requires 10 spacetime dimensions, and originates from a more fundamental 11-dimensional theory tentatively called M-theory which subsumes five previously distinct superstring theories. Supergravity theory also promotes 11D spacetime = 7D hyperspace + 4 common dimensions. To date, no direct experimental or observational evidence

Land warfare - Misplaced Pages Continue

1824-415: The 19th century, via the work of Arthur Cayley , William Rowan Hamilton , Ludwig Schläfli and Bernhard Riemann . Riemann's 1854 Habilitationsschrift , Schläfli's 1852 Theorie der vielfachen Kontinuität , and Hamilton's discovery of the quaternions and John T. Graves ' discovery of the octonions in 1843 marked the beginning of higher-dimensional geometry. The rest of this section examines some of

1881-521: The advent of powered flight at the start of the 20th century, artillery also included ground-based anti-aircraft batteries. Combined arms is an approach to warfare which seeks to integrate different arms of a military to achieve mutually complementary effects, such as, self-propelled artillery , mechanized infantry , aircraft and so forth. Terrain Terrain (from Latin : terra 'earth'), alternatively relief or topographical relief ,

1938-448: The complex dimension is half the real dimension. Conversely, in algebraically unconstrained contexts, a single complex coordinate system may be applied to an object having two real dimensions. For example, an ordinary two-dimensional spherical surface , when given a complex metric, becomes a Riemann sphere of one complex dimension. The dimension of an algebraic variety may be defined in various equivalent ways. The most intuitive way

1995-461: The curve to a fixed point on the curve. This is independent from the fact that a curve cannot be embedded in a Euclidean space of dimension lower than two, unless it is a line. The dimension of Euclidean n -space E is n . When trying to generalize to other types of spaces, one is faced with the question "what makes E n -dimensional?" One answer is that to cover a fixed ball in E by small balls of radius ε , one needs on

2052-468: The dimension by one unless if the hyperplane contains the variety. An algebraic set being a finite union of algebraic varieties, its dimension is the maximum of the dimensions of its components. It is equal to the maximal length of the chains V 0 ⊊ V 1 ⊊ ⋯ ⊊ V d {\displaystyle V_{0}\subsetneq V_{1}\subsetneq \cdots \subsetneq V_{d}} of sub-varieties of

2109-408: The dimension of an object is, roughly speaking, the number of degrees of freedom of a point that moves on this object. In other words, the dimension is the number of independent parameters or coordinates that are needed for defining the position of a point that is constrained to be on the object. For example, the dimension of a point is zero; the dimension of a line is one, as a point can move on

2166-450: The direction of increasing entropy ). The best-known treatment of time as a dimension is Poincaré and Einstein 's special relativity (and extended to general relativity ), which treats perceived space and time as components of a four-dimensional manifold , known as spacetime , and in the special, flat case as Minkowski space . Time is different from other spatial dimensions as time operates in all spatial dimensions. Time operates in

2223-522: The discharge of projectiles during the war. The term also describes ground-based troops, who primarily manned such weapons. The word is derived from the Old French verb attilier, meaning "to equip". This term includes coastal artillery which traditionally defended coastal areas against seaborne attack and controlled the passage of ships using their ability to deny access through the threat of coastal fire. It also includes land-based field artillery. With

2280-409: The empty set can be taken to have dimension -1. Similarly, for the class of CW complexes , the dimension of an object is the largest n for which the n -skeleton is nontrivial. Intuitively, this can be described as follows: if the original space can be continuously deformed into a collection of higher-dimensional triangles joined at their faces with a complicated surface, then the dimension of

2337-408: The first, second and third as well as theoretical spatial dimensions such as a fourth spatial dimension . Time is not however present in a single point of absolute infinite singularity as defined as a geometric point , as an infinitely small point can have no change and therefore no time. Just as when an object moves through positions in space, it also moves through positions in time. In this sense

Land warfare - Misplaced Pages Continue

2394-428: The given algebraic set (the length of such a chain is the number of " ⊊ {\displaystyle \subsetneq } "). Each variety can be considered as an algebraic stack , and its dimension as variety agrees with its dimension as stack. There are however many stacks which do not correspond to varieties, and some of these have negative dimension. Specifically, if V is a variety of dimension m and G

2451-431: The land away by smoothing and reducing topographic features. The relationship of erosion and tectonics rarely (if ever) reaches equilibrium. These processes are also codependent, however the full range of their interactions is still a topic of debate. Land surface parameters are quantitative measures of various morphometric properties of a surface. The most common examples are used to derive slope or aspect of

2508-430: The matter associated with our visible universe is localized on a (3 + 1)-dimensional subspace. Thus, the extra dimensions need not be small and compact but may be large extra dimensions . D-branes are dynamical extended objects of various dimensionalities predicted by string theory that could play this role. They have the property that open string excitations, which are associated with gauge interactions, are confined to

2565-463: The means to mobilize heavy firepower to engage opposing forces including other combat vehicles. Combat vehicles are usually equipped to drive in rugged terrain . They are usually protected against other common threats with armor and other countermeasures . Examples of combat vehicles include main battle tanks , infantry fighting vehicles , and self-propelled artillery . Historically, artillery (from French artillerie) refers to any engine used for

2622-490: The more important mathematical definitions of dimension. The dimension of a vector space is the number of vectors in any basis for the space, i.e. the number of coordinates necessary to specify any vector. This notion of dimension (the cardinality of a basis) is often referred to as the Hamel dimension or algebraic dimension to distinguish it from other notions of dimension. For the non- free case, this generalizes to

2679-398: The motion of an observer . Minkowski space first approximates the universe without gravity ; the pseudo-Riemannian manifolds of general relativity describe spacetime with matter and gravity. 10 dimensions are used to describe superstring theory (6D hyperspace + 4D), 11 dimensions can describe supergravity and M-theory (7D hyperspace + 4D), and the state-space of quantum mechanics

2736-428: The notion of the length of a module . The uniquely defined dimension of every connected topological manifold can be calculated. A connected topological manifold is locally homeomorphic to Euclidean n -space, in which the number n is the manifold's dimension. For connected differentiable manifolds , the dimension is also the dimension of the tangent vector space at any point. In geometric topology ,

2793-601: The object is the dimension of those triangles. The Hausdorff dimension is useful for studying structurally complicated sets, especially fractals . The Hausdorff dimension is defined for all metric spaces and, unlike the dimensions considered above, can also have non-integer real values. The box dimension or Minkowski dimension is a variant of the same idea. In general, there exist more definitions of fractal dimensions that work for highly irregular sets and attain non-integer positive real values. Every Hilbert space admits an orthonormal basis , and any two such bases for

2850-587: The order of ε such small balls. This observation leads to the definition of the Minkowski dimension and its more sophisticated variant, the Hausdorff dimension , but there are also other answers to that question. For example, the boundary of a ball in E looks locally like E and this leads to the notion of the inductive dimension . While these notions agree on E , they turn out to be different when one looks at more general spaces. A tesseract

2907-450: The realization that gravity propagating in small, compact extra dimensions is equivalent to gauge interactions at long distances. In particular when the geometry of the extra dimensions is trivial, it reproduces electromagnetism . However, at sufficiently high energies or short distances, this setup still suffers from the same pathologies that famously obstruct direct attempts to describe quantum gravity . Therefore, these models still require

SECTION 50

#1732779782342

2964-406: The same way that humans commonly perceive it. The equations of classical mechanics are symmetric with respect to time , and equations of quantum mechanics are typically symmetric if both time and other quantities (such as charge and parity ) are reversed. In these models, the perception of time flowing in one direction is an artifact of the laws of thermodynamics (we perceive time as flowing in

3021-462: The size of the area over which it is measured, making the definition of the scale over which it is measured very important. Because it is related to the slope of surfaces within the area of interest and to the gradient of any streams present, the relief of a landscape is a useful metric in the study of the Earth's surface. Relief energy, which may be defined inter alia as "the maximum height range in

3078-412: The smallest integer n for which the following holds: any open cover has an open refinement (a second open cover in which each element is a subset of an element in the first cover) such that no point is included in more than n + 1 elements. In this case dim X = n . For X a manifold, this coincides with the dimension mentioned above. If no such integer n exists, then the dimension of X

3135-424: The storage, analysis, and visualization of geometric shapes, including illustration software , Computer-aided design , and Geographic information systems . Different vector systems use a wide variety of data structures to represent shapes, but almost all are fundamentally based on a set of geometric primitives corresponding to the spatial dimensions: Frequently in these systems, especially GIS and Cartography ,

3192-483: The theory of manifolds is characterized by the way dimensions 1 and 2 are relatively elementary, the high-dimensional cases n > 4 are simplified by having extra space in which to "work"; and the cases n = 3 and 4 are in some senses the most difficult. This state of affairs was highly marked in the various cases of the Poincaré conjecture , in which four different proof methods are applied. The dimension of

3249-463: The variety of doctrines used to prosecute warfare on land. Land forces include personnel , weapons platforms , vehicles , and support elements operating on land to accomplish assigned missions and tasks. Infantry are soldiers who fight primarily on foot with small arms in organized military units . However, they may be transported to the battlefield by ships , automobiles , skis , cargo planes, or other means. Combat vehicles provide

#341658