This is the documentation for the Abstraction Ontology. All instances of the Abstraction class are listed here. An abstraction is a mental mathematical model that is applied to observed phenomena to approximate the spatiotemporal behavior of that phenomenon. Abstractions that are derived from physical theories are physical abstractions.

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Documentation last generated on 2019-04-29 13:06 EDT.

airfoil

Alternative labels for this instance are: aerofoil.

This instance has a related Wikipedia page. Short extract:
An airfoil (American English) or aerofoil (British English) is the cross-sectional shape of a wing, blade (of a propeller, rotor, or turbine), or sail (as seen in cross-section). An airfoil-shaped body moved through a fluid process, produces an aerodynamic force.

This instance is a narrower concept derived from shape.

airfoil_curve~enclosing

This abstraction represents airfoil as abstracted by curve%257Eenclosing.

airfoil

This instance is a narrower concept derived from airfoil.

This instance describes the process drifting.

airfoil

This instance is a narrower concept derived from airfoil.

This instance describes the process lift.

amphidromic-points

This instance has a related Wikipedia page. Short extract:
An amphidromic point, also called a tidal node, is a geographical location which has zero tidal amplitude for one harmonic constituent of the tide. The tidal range (the peak-to-peak amplitude, or height difference between high tide and low tide) for that harmonic constituent increases with distance from this point.The term amphidromic point derives from the Greek words amphi (around) and dromos (running), referring to the rotary tides running around them.

This instance is a narrower concept derived from points.

This instance has the following attributes:

apex

This instance has a related Wikipedia page. Short extract:
In geometry, an apex (Latin for 'summit, peak, tip, top, extreme end') is the vertex which is in some sense the "highest" of the figure to which it belongs.

This instance is a narrower concept derived from point.

aphelion

This instance has a related Wikipedia page. Short extract:
Apsis (Greek: ἁψίς; plural apsides , Greek: ἁψῖδες; "orbit") denotes either of the two extreme points—ie, the farthest or nearest point—in the orbit of a planetary body about its primary body (or simply, "the primary"). The plural term, "apsides", usually implies both apsis points (i.e., farthest and nearest); apsides can also refer to the distance of the extreme range of an object orbiting a host body.

This instance is a narrower concept derived from point.

axis

This instance is a narrower concept derived from line.

axis~east

This instance is a narrower concept derived from axis.

This instance has the following attributes:

axis~semi-major

This instance has a related Wikipedia page. Short extract:
In geometry, the major axis of an ellipse is its longest diameter: a line segment that runs through the center and both foci, with ends at the widest points of the perimeter. The semi-major axis (more properly, major semi-axis) is one half of the major axis, and thus runs from the centre, through a focus, and to the perimeter.

This instance is a narrower concept derived from axis.

This instance has the following attributes:

axis~semi-minor

This instance has a related Wikipedia page. Short extract:
In geometry, the major axis of an ellipse is its longest diameter: a line segment that runs through the center and both foci, with ends at the widest points of the perimeter. The semi-major axis (more properly, major semi-axis) is one half of the major axis, and thus runs from the centre, through a focus, and to the perimeter.

This instance is a narrower concept derived from axis.

This instance has the following attributes:

axis~vertical

This instance is a narrower concept derived from axis.

This instance has the following attributes:

axis~x

This instance is a narrower concept derived from axis.

This instance has the following attributes:

binary-mask

This instance is a narrower concept derived from mask.

This instance has the following attributes:

black-body

This instance has a related Wikipedia page. Short extract:
A black body or blackbody is an idealized physical body that absorbs all incident electromagnetic radiation, regardless of frequency or angle of incidence. (It does not only absorb radiation, but can also emit radiation.

This instance is a narrower concept derived from model.

boundary

Alternative labels for this instance are: contour.

This instance has a related Wikipedia page. Short extract:
In topology and mathematics in general, the boundary of a subset S of a topological space X is the set of points which can be approached both from S and from the outside of S. More precisely, it is the set of points in the closure of S not belonging to the interior of S. An element of the boundary of S is called a boundary point of S. The term boundary operation refers to finding or taking the boundary of a set. Notations used for boundary of a set S include bd(S), fr(S), and ∂S. Some authors (for example Willard, in General Topology) use the term frontier instead of boundary in an attempt to avoid confusion with the concept of boundary used in algebraic topology and manifold theory.

This instance is a narrower concept derived from point-set.

boundary~core-mantle

This instance has a related Wikipedia page. Short extract:
The core–mantle boundary (CMB in the parlance of solid earth geophysicists) of the Earth lies between the planet's silicate mantle and its liquid iron-nickel outer core. This boundary is located at approximately 2891 km (1796 mi) depth beneath the Earth's surface.

This instance is a narrower concept derived from boundary.

This instance has the following attributes:

boundary~crust-mantle

This instance is a narrower concept derived from boundary.

This instance has the following attributes:

boundary~lithosphere-asthenosphere

This instance has a related Wikipedia page. Short extract:
The Lithosphere–asthenosphere boundary (LAB) represents a mechanical difference between layers in Earth's inner structure. Earth's inner structure can be described both chemically (crust, mantle, core) and mechanically.

This instance is a narrower concept derived from boundary.

This instance has the following attributes:

boundary~seaward

This instance is a narrower concept derived from boundary.

This instance has the following attributes:

cantor-set

This instance has a related Wikipedia page. Short extract:
In mathematics, the Cantor set is a set of points lying on a single line segment that has a number of remarkable and deep properties. It was discovered in 1874 by Henry John Stephen Smith and introduced by German mathematician Georg Cantor in 1883.Through consideration of this set, Cantor and others helped lay the foundations of modern point-set topology.

This instance is a narrower concept derived from point-set.

cell

This instance is a narrower concept derived from partition.

cell~dual

This instance is a narrower concept derived from cell.

This instance has the following attributes:

cell~primary

This instance is a narrower concept derived from cell.

This instance has the following attributes:

center

This instance has a related Wikipedia page. Short extract:
In geometry, a center (or centre) (from Greek κέντρον) of an object is a point in some sense in the middle of the object. According to the specific definition of center taken into consideration, an object might have no center If geometry is regarded as the study of isometry groups then a center is a fixed point of all the isometries which move the object onto itself.

This instance is a narrower concept derived from point.

centerline

This instance is a narrower concept derived from line.

centroid

This instance has a related Wikipedia page. Short extract:
In mathematics and physics, the centroid or geometric center of a plane figure is the arithmetic mean position of all the points in the figure. Informally, it is the point at which a cutout of the shape could be perfectly balanced on the tip of a pin.The definition extends to any object in n-dimensional space: its centroid is the mean position of all the points in all of the coordinate directions.While in geometry the word barycenter is a synonym for centroid, in astrophysics and astronomy, the barycenter is the center of mass of two or more bodies that orbit each other.

This instance is a narrower concept derived from point.

circle

This instance has a related Wikipedia page. Short extract:
A circle is a simple closed shape. It is the set of all points in a plane that are at a given distance from a given point, the centre; equivalently it is the curve traced out by a point that moves in a plane so that its distance from a given point is constant.

This instance is a narrower concept derived from shape.

column

This instance has a related Wikipedia page. Short extract:
In linear algebra, the column space (also called the range or image) of a matrix A is the span (set of all possible linear combinations) of its column vectors. The column space of a matrix is the image or range of the corresponding matrix transformation.

This instance is a narrower concept derived from partition.

contour

Alternative labels for this instance are: isocline.

This instance has a related Wikipedia page. Short extract:
A contour line (also isoline, isopleth, or isarithm) of a function of two variables is a curve along which the function has a constant value, so that the curve joins points of equal value. It is a plane section of the three-dimensional graph of the function f(x, y) parallel to the x, y plane.

This instance is a narrower concept derived from point-set.

crest

This instance has a related Wikipedia page. Short extract:
A crest is the point on a wave with the maximum value of upward displacement within a cycle. A crest is a point on a surface wave where the displacement of the medium is at a maximum.

crest_x-section

This abstraction represents crest as abstracted by x-section.

crest_x-section_vertex

This abstraction represents crest_x-section as abstracted by vertex.

crestline

This instance is a narrower concept derived from line.

curve

This instance has a related Wikipedia page. Short extract:
In mathematics, a curve (also called a curved line in older texts) is, generally speaking, an object similar to a line but that need not be straight. Thus, a curve is a generalization of a line, in that its curvature need not be zero.Various disciplines within mathematics have given the term different meanings depending on the area of study, so the precise meaning depends on context.

curve~enclosing

This instance is a narrower concept derived from curve.

This instance has the following attributes:

data-stream

datum

datum~vertical

This instance is a narrower concept derived from datum.

This instance has the following attributes:

datum~vertical~geodetic

This instance is a narrower concept derived from datum~vertical.

This instance has the following attributes:

datum~vertical~gravimetric

This instance is a narrower concept derived from datum~vertical.

This instance has the following attributes:

datum~vertical~tidal

This instance is a narrower concept derived from datum~vertical.

This instance has the following attributes:

datum~vertical~tidal~msl

This instance is a narrower concept derived from datum~vertical~tidal.

This instance has the following attributes:

datum_ellipsoid

This abstraction represents datum as abstracted by ellipsoid.

datum_ellipsoid_surface

This abstraction represents datum_ellipsoid as abstracted by surface.

datum_geodesic

This abstraction represents datum as abstracted by geodesic.

ecliptic

This instance has a related Wikipedia page. Short extract:
The ecliptic is the mean plane of the apparent path in the Earth's sky that the Sun follows over the course of one year; it is the basis of the ecliptic coordinate system. This plane of reference is coplanar with Earth's orbit around the Sun (and hence the Sun's apparent path around Earth).

ellipse

This instance has a related Wikipedia page. Short extract:
In mathematics, an ellipse is a curve in a plane surrounding two focal points such that the sum of the distances to the two focal points is constant for every point on the curve. As such, it is a generalization of a circle, which is a special type of an ellipse having both focal points at the same location.

This instance is a narrower concept derived from shape.

ellipsoid

This instance has a related Wikipedia page. Short extract:
An ellipsoid is a surface that may be obtained from a sphere by deforming it by means of directional scalings, or more generally, of an affine transformation. An ellipsoid is a quadric surface;  that is, a surface that may be defined as the zero set of a polynomial of degree two in three variables.

This instance is a narrower concept derived from shape.

endpoint

This instance has a related Wikipedia page. Short extract:
An endpoint, end-point or end point may refer to:

This instance is a narrower concept derived from point.

endpoint~downstream

This instance is a narrower concept derived from endpoint.

This instance has the following attributes:

endpoint~upstream

This instance is a narrower concept derived from endpoint.

This instance has the following attributes:

endpoints

This instance is a plurality of endpoint.

This instance has a related Wikipedia page. Short extract:
An endpoint, end-point or end point may refer to:

This instance is a narrower concept derived from points.

epicenter

This instance has a related Wikipedia page. Short extract:
The epicenter, epicentre or epicentrum in seismology is the point on the Earth's surface directly above a hypocenter or focus, the point where an earthquake or an underground explosion originates.

This instance is a narrower concept derived from point.

equation

This instance has a related Wikipedia page. Short extract:
In mathematics, an equation is a statement that asserts the equality of two expressions. The word equation and its cognates in other languages may have subtly different meanings; for example, in French an équation is defined as containing one or more variables, while in English any equality is an equation.Solving an equation containing variables consists of determining which values of the variables make the equality true.

equation~convection-diffusion

This instance has a related Wikipedia page. Short extract:
The convection–diffusion equation is a combination of the diffusion and convection (advection) equations, and describes physical phenomena where particles, energy, or other physical quantities are transferred inside a physical system due to two processes: diffusion and convection. Depending on context, the same equation can be called the advection–diffusion equation, drift–diffusion equation, or (generic) scalar transport equation.

This instance is a narrower concept derived from equation.

This instance describes the process convection. This instance describes the process diffusion.

equation~heat

This instance has a related Wikipedia page. Short extract:
In physics and mathematics, the heat equation is a partial differential equation that describes how the distribution of some quantity (such as heat) evolves over time in a solid medium, as it spontaneously flows from places where it is higher towards places where it is lower. It is a special case of the diffusion equation.

This instance is a narrower concept derived from equation.

equation~navier-stokes

This instance has a related Wikipedia page. Short extract:
In physics, the Navier–Stokes equations (), named after Claude-Louis Navier and George Gabriel Stokes, describe the motion of viscous fluid substances. These balance equations arise from applying Isaac Newton's second law to fluid motion, together with the assumption that the stress in the fluid is the sum of a diffusing viscous term (proportional to the gradient of velocity) and a pressure term—hence describing viscous flow.

This instance is a narrower concept derived from equation.

equation~poisson

This instance has a related Wikipedia page. Short extract:
In mathematics, Poisson's equation is a partial differential equation of elliptic type with broad utility in mechanical engineering and theoretical physics. It arises, for instance, to describe the potential field caused by a given charge or mass density distribution; with the potential field known, one can then calculate gravitational or electrostatic field.

This instance is a narrower concept derived from equation.

equations

This instance is a plurality of equation.

equator

This instance has a related Wikipedia page. Short extract:
An equator of a rotating spheroid (such as a planet) is its zeroth circle of latitude (parallel). It is the imaginary line on the spheroid, equidistant from its poles, dividing it into northern and southern hemispheres.

This instance is a narrower concept derived from line.

equator_plane

This abstraction represents equator as abstracted by plane.

equilibrium-line

This instance is a narrower concept derived from line.

This instance has the following attributes:

expression

This instance has a related Wikipedia page. Short extract:
In mathematics, an expression or mathematical expression is a finite combination of symbols that is well-formed according to rules that depend on the context. Mathematical symbols can designate numbers (constants), variables, operations, functions, brackets, punctuation, and grouping to help determine order of operations, and other aspects of logical syntax.

face

This instance has a related Wikipedia page. Short extract:
In solid geometry, a face is a flat (planar) surface that forms part of the boundary of a solid object; a three-dimensional solid bounded exclusively by flat faces is a polyhedron. In more technical treatments of the geometry of polyhedra and higher-dimensional polytopes, the term is also used to mean an element of any dimension of a more general polytope (in any number of dimensions).

This instance is a narrower concept derived from shape.

foci

This instance is a plurality of focus.

This instance is a narrower concept derived from points.

focus

This instance has a related Wikipedia page. Short extract:
In geometry, focuses or foci (UK: , US: ), singular focus, are special points with reference to which any of a variety of curves is constructed. For example, one or two foci can be used in defining conic sections, the four types of which are the circle, ellipse, parabola, and hyperbola.

This instance is a narrower concept derived from point.

friedmann-universe

This instance has a related Wikipedia page. Short extract:
The Friedmann equations are a set of equations in physical cosmology that govern the expansion of space in homogeneous and isotropic models of the universe within the context of general relativity. They were first derived by Alexander Friedmann in 1922 from Einstein's field equations of gravitation for the Friedmann–Lemaître–Robertson–Walker metric and a perfect fluid with a given mass density ρ {\displaystyle \rho } and pressure p {\displaystyle p} .

This instance is a narrower concept derived from equations.

function

This instance has a related Wikipedia page. Short extract:
In mathematics, a function was originally the idealization of how a varying quantity depends on another quantity. For example, the position of a planet is a function of time.

geocenter

This instance is a narrower concept derived from point.

geodesic

This instance has a related Wikipedia page. Short extract:
In differential geometry, a geodesic () is a curve representing in some sense the shortest path between two points in a surface, or more generally in a Riemannian manifold. It is a generalization of the notion of a "straight line" to a more general setting.

This instance is a narrower concept derived from line.

geoid

This instance is a narrower concept derived from model.

graph

This instance has a related Wikipedia page. Short extract:
In mathematics, and more specifically in graph theory, a graph is a structure amounting to a set of objects in which some pairs of the objects are in some sense "related". The objects correspond to mathematical abstractions called vertices (also called nodes or points) and each of the related pairs of vertices is called an edge (also called link or line).

graph~tree

This instance has a related Wikipedia page. Short extract:
In mathematics, and, more specifically, in graph theory, a tree is an undirected graph in which any two vertices are connected by exactly one path. Every acyclic connected graph is a tree, and vice versa.

This instance is a narrower concept derived from graph.

graph~tree~rooted

This instance is a narrower concept derived from graph~tree.

grid

This instance has a related Wikipedia page. Short extract:
A lattice graph, mesh graph, or grid graph, is a graph whose drawing, embedded in some Euclidean space Rn, forms a regular tiling. This implies that the group of bijective transformations that send the graph to itself is a lattice in the group-theoretical sense.

This instance is a narrower concept derived from graph.

grid_axis~x

This abstraction represents grid as abstracted by axis%257Ex.

grid_bottom

This instance has the following components:

grid_cell

This abstraction represents grid as abstracted by cell.

grid_cell~dual

This abstraction represents grid as abstracted by cell%257Edual.

grid_cell~dual_centroid

This abstraction represents grid_cell%257Edual as abstracted by centroid.

grid_cell~dual_column

This abstraction represents grid_cell%257Edual as abstracted by column.

grid_cell~dual_edge

This instance has the following components:

grid_cell~dual_edge_center

This abstraction represents grid_cell%257Edual_edge as abstracted by center.

grid_cell~dual_face

This instance has the following components:

grid_cell~dual_face_centroid

This abstraction represents grid_cell%257Edual_face as abstracted by centroid.

grid_cell~dual_row

This abstraction represents grid_cell%257Edual as abstracted by row.

grid_cell~dual_surface

This abstraction represents grid_cell%257Edual as abstracted by surface.

grid_cell~primary

This abstraction represents grid as abstracted by cell%257Eprimary.

grid_cell~primary_centroid

This abstraction represents grid_cell%257Eprimary as abstracted by centroid.

grid_cell~primary_column

This abstraction represents grid_cell%257Eprimary as abstracted by column.

grid_cell~primary_edge

This instance has the following components:

grid_cell~primary_edge_center

This abstraction represents grid_cell%257Eprimary_edge as abstracted by center.

grid_cell~primary_face

This instance has the following components:

grid_cell~primary_face_centroid

This abstraction represents grid_cell%257Eprimary_face as abstracted by centroid.

grid_cell~primary_row

This abstraction represents grid_cell%257Eprimary as abstracted by row.

grid_cell~primary_surface

This abstraction represents grid_cell%257Eprimary as abstracted by surface.

grid_cell_center

This abstraction represents grid_cell as abstracted by center.

grid_cell_centroid

This abstraction represents grid_cell as abstracted by centroid.

grid_cell_column

This abstraction represents grid_cell as abstracted by column.

grid_cell_edge

This instance has the following components:

grid_cell_edge~east

This instance has the following components:

grid_cell_edge~north

This instance has the following components:

grid_cell_edge~south

This instance has the following components:

grid_cell_edge~west

This instance has the following components:

grid_cell_edge~x

This instance has the following components:

grid_cell_edge~y

This instance has the following components:

grid_cell_edge_center

This abstraction represents grid_cell_edge as abstracted by center.

grid_cell_face

This instance has the following components:

grid_cell_face_centroid

This abstraction represents grid_cell_face as abstracted by centroid.

grid_cell_row

This abstraction represents grid_cell as abstracted by row.

grid_cell_row-major-offset

This abstraction represents grid_cell as abstracted by row-major-offset.

grid_cell_surface

This abstraction represents grid_cell as abstracted by surface.

grid_column

This abstraction represents grid as abstracted by column.

grid_edge~east

This instance has the following components:

grid_edge~north

This instance has the following components:

grid_edge~south

This instance has the following components:

grid_edge~west

This instance has the following components:

grid_node

This abstraction represents grid as abstracted by node.

grid_node~dual

This abstraction represents grid as abstracted by node%257Edual.

grid_node~dual~x

This abstraction represents grid as abstracted by node%257Edual%257Ex.

grid_node~dual~y

This abstraction represents grid as abstracted by node%257Edual%257Ey.

grid_node~dual~z

This abstraction represents grid as abstracted by node%257Edual%257Ez.

grid_node~primary

This abstraction represents grid as abstracted by node%257Eprimary.

grid_node~primary~x

This abstraction represents grid as abstracted by node%257Eprimary%257Ex.

grid_node~primary~y

This abstraction represents grid as abstracted by node%257Eprimary%257Ey.

grid_node~primary~z

This abstraction represents grid as abstracted by node%257Eprimary%257Ez.

grid_row

This abstraction represents grid as abstracted by row.

grid_shell

This abstraction represents grid as abstracted by shell.

grid_top

This instance has the following components:

hypocenter

Alternative labels for this instance are: focus.

This instance has a related Wikipedia page. Short extract:
A hypocenter (or hypocentre) (from Ancient Greek: ὑπόκεντρον [hypόkentron] for 'below the center') is the point of origin of an earthquake or a subsurface nuclear explosion. In seismology, it is a synonym of the focus.

This instance is a narrower concept derived from point.

image

isocline

This instance has a related Wikipedia page. Short extract:
A contour line (also isoline, isopleth, or isarithm) of a function of two variables is a curve along which the function has a constant value, so that the curve joins points of equal value. It is a plane section of the three-dimensional graph of the function f(x, y) parallel to the x, y plane.

This instance is a narrower concept derived from line.

isosurface

This instance has a related Wikipedia page. Short extract:
An isosurface is a three-dimensional analog of an isoline. It is a surface that represents points of a constant value (e.g.

This instance is a narrower concept derived from surface.

isosurface~potential-temperature

This instance is a narrower concept derived from isosurface.

This instance has the following attributes:

land-mask

This instance is a narrower concept derived from mask.

This instance has the following attributes:

line

This instance has a related Wikipedia page. Short extract:
Line, lines or LINE may refer to:

location

This instance is a narrower concept derived from point.

market-basket

This instance has a related Wikipedia page. Short extract:
A market basket or commodity bundle is a fixed list of items, in given proportions, used specifically to track the progress of inflation in an economy or specific market.

This instance is a narrower concept derived from model.

mask

This instance has a related Wikipedia page. Short extract:
In computer science, a mask or bitmask is data that is used for bitwise operations, particularly in a bit field. Using a mask, multiple bits in a byte, nibble, word etc.

math

This instance has a related Wikipedia page. Short extract:
Mathematics (from Greek μάθημα máthēma, "knowledge, study, learning") includes the study of such topics as quantity, structure, space, and change.Mathematicians seek and use patterns to formulate new conjectures; they resolve the truth or falsity of conjectures by mathematical proof. When mathematical structures are good models of real phenomena, then mathematical reasoning can provide insight or predictions about nature.

This instance is a narrower concept derived from model.

model

This instance has a related Wikipedia page. Short extract:
Model, modeling or modelling may refer to:

mohr-coulomb-plastic

This instance has a related Wikipedia page. Short extract:
Mohr–Coulomb theory is a mathematical model (see yield surface) describing the response of brittle materials such as concrete, or rubble piles, to shear stress as well as normal stress. Most of the classical engineering materials somehow follow this rule in at least a portion of their shear failure envelope.

This instance is a narrower concept derived from model.

node

This instance is a narrower concept derived from point.

node~dual

This instance is a narrower concept derived from node.

This instance has the following attributes:

node~dual~x

This instance is a narrower concept derived from node~dual.

This instance has the following attributes:

node~dual~y

This instance is a narrower concept derived from node~dual.

This instance has the following attributes:

node~dual~z

This instance is a narrower concept derived from node~dual.

This instance has the following attributes:

node~primary

This instance is a narrower concept derived from node.

This instance has the following attributes:

node~primary~x

This instance is a narrower concept derived from node~primary.

This instance has the following attributes:

node~primary~y

This instance is a narrower concept derived from node~primary.

This instance has the following attributes:

node~primary~z

This instance is a narrower concept derived from node~primary.

This instance has the following attributes:

origin

This instance is a narrower concept derived from point.

parabola

This instance has a related Wikipedia page. Short extract:
In mathematics, a parabola is a plane curve that is mirror-symmetrical and is approximately U-shaped. It fits several superficially different other mathematical descriptions, which can all be proved to define exactly the same curves.

This instance is a narrower concept derived from curve.

partition

This instance has a related Wikipedia page. Short extract:
In mathematics, a partition of an interval [a, b] on the real line is a finite sequence x0, x1, x2, ..., xk of real numbers such that a = x0 < x1 < x2 < ... < xk = b.In other terms, a partition of a compact interval I is a strictly increasing sequence of numbers (belonging to the interval I itself) starting from the initial point of I and arriving at the final point of I. Every interval of the form [xi, xi + 1] is referred to as a subinterval of the partition x.

peano-curve

This instance has a related Wikipedia page. Short extract:
In geometry, the Peano curve is the first example of a space-filling curve to be discovered, by Giuseppe Peano in 1890. Peano's curve is a surjective, continuous function from the unit interval onto the unit square, however it is not injective.

This instance is a narrower concept derived from curve.

perihelion

This instance has a related Wikipedia page. Short extract:
Apsis (Greek: ἁψίς; plural apsides , Greek: ἁψῖδες; "orbit") denotes either of the two extreme points—ie, the farthest or nearest point—in the orbit of a planetary body about its primary body (or simply, "the primary"). The plural term, "apsides", usually implies both apsis points (i.e., farthest and nearest); apsides can also refer to the distance of the extreme range of an object orbiting a host body.

This instance is a narrower concept derived from point.

physics

This instance has a related Wikipedia page. Short extract:
Physics (from Ancient Greek: φυσική (ἐπιστήμη), translit. physikḗ (epistḗmē), lit.

This instance is a narrower concept derived from model.

plan

plane

This instance has a related Wikipedia page. Short extract:
In mathematics, a plane is a flat, two-dimensional surface that extends infinitely far. A plane is the two-dimensional analogue of a point (zero dimensions), a line (one dimension) and three-dimensional space.

point

This instance has a related Wikipedia page. Short extract:
Point or points may refer to:

point-set

points

This instance is a plurality of point.

pole

This instance has a related Wikipedia page. Short extract:
The poles of astronomical bodies are determined based on their axis of rotation in relation to the celestial poles of the celestial sphere. Astronomical bodies include stars, planets, dwarf planets and small Solar System bodies such as comets and minor planets (i.e.

This instance is a narrower concept derived from point.

pole~north

This instance has a related Wikipedia page. Short extract:
North Pole may refer to:

This instance is a narrower concept derived from pole.

This instance has the following attributes:

pole~north~magnetic

This instance has a related Wikipedia page. Short extract:
The North Magnetic Pole is the wandering point on the surface of Earth's Northern Hemisphere at which the planet's magnetic field points vertically downwards (in other words, if a magnetic compass needle is allowed to rotate about a horizontal axis, it will point straight down). There is only one location where this occurs, near (but distinct from) the Geographic North Pole and the Geomagnetic North Pole.

This instance is a narrower concept derived from pole~north.

This instance has the following attributes:

pole~north~terrestrial

This instance has a related Wikipedia page. Short extract:
The North Pole, also known as the Geographic North Pole or Terrestrial North Pole, is (subject to the caveats explained below) defined as the point in the Northern Hemisphere where the Earth's axis of rotation meets its surface. The North Pole is the northernmost point on the Earth, lying diametrically opposite the South Pole.

This instance is a narrower concept derived from pole~north.

This instance has the following attributes:

pole~north~virtual

This instance is a narrower concept derived from pole~north.

This instance has the following attributes:

pole~south

This instance has a related Wikipedia page. Short extract:
South Pole may refer to:

This instance is a narrower concept derived from pole.

This instance has the following attributes:

pole~south~magnetic

This instance has a related Wikipedia page. Short extract:
The South Magnetic Pole is the wandering point on Earth's Southern Hemisphere where the geomagnetic field lines are directed vertically upwards. It should not be confused with the South Geomagnetic Pole described later.

This instance is a narrower concept derived from pole~south.

This instance has the following attributes:

pole~south~terrestrial

This instance has a related Wikipedia page. Short extract:
The South Pole, also known as the Geographic South Pole or Terrestrial South Pole, is one of the two points where Earth's axis of rotation intersects its surface. It is the southernmost point on the surface of Earth and lies on the opposite side of Earth from the North Pole.

This instance is a narrower concept derived from pole~south.

This instance has the following attributes:

polygon

This instance has a related Wikipedia page. Short extract:
In elementary geometry, a polygon () is a plane figure that is described by a finite number of straight line segments connected to form a closed polygonal chain or polygonal circuit. The solid plane region, the bounding circuit, or the two together, may be called a polygon.

This instance is a narrower concept derived from shape.

polynomial

This instance has a related Wikipedia page. Short extract:
In mathematics, a polynomial is an expression consisting of variables (also called indeterminates) and coefficients, that involves only the operations of addition, subtraction, multiplication, and non-negative integer exponents of variables. An example of a polynomial of a single indeterminate, x, is x2 − 4x + 7.

This instance is a narrower concept derived from expression.

profile

profile_bottom

This instance has the following components:

ray

This instance is a narrower concept derived from line.

response-filter

row

This instance has a related Wikipedia page. Short extract:
In linear algebra, the column space (also called the range or image) of a matrix A is the span (set of all possible linear combinations) of its column vectors. The column space of a matrix is the image or range of the corresponding matrix transformation.

This instance is a narrower concept derived from partition.

row-major-offset

sea-mask

This instance is a narrower concept derived from mask.

This instance has the following attributes:

shape

This instance has a related Wikipedia page. Short extract:
A shape is the form of an object or its external boundary, outline, or external surface, as opposed to other properties such as color, texture or material composition.

shell

shoreline

This instance is a narrower concept derived from line.

shoreline_axis~x

This abstraction represents shoreline as abstracted by axis%257Ex.

sierpinski-gasket

Alternative labels for this instance are: sierpinski-triangle.

This instance has a related Wikipedia page. Short extract:
The Sierpinski triangle (also with the original orthography Sierpiński), also called the Sierpinski gasket or Sierpinski sieve, is a fractal and attractive fixed set with the overall shape of an equilateral triangle, subdivided recursively into smaller equilateral triangles. Originally constructed as a curve, this is one of the basic examples of self-similar sets–that is, it is a mathematically generated pattern that is reproducible at any magnification or reduction.

This instance is a narrower concept derived from point-set.

sphere

This instance has a related Wikipedia page. Short extract:
A sphere (from Greek σφαῖρα — sphaira, "globe, ball") is a perfectly round geometrical object in three-dimensional space that is the surface of a completely round ball (viz., analogous to the circular objects in two dimensions, where a "circle" circumscribes its "disk"). Like a circle in a two-dimensional space, a sphere is defined mathematically as the set of points that are all at the same distance r from a given point, but in a three-dimensional space.

This instance is a narrower concept derived from shape.

sphere_surface

This abstraction represents sphere as abstracted by surface.

square

This instance has a related Wikipedia page. Short extract:
In geometry, a square is a regular quadrilateral, which means that it has four equal sides and four equal angles (90-degree angles, or (100-gradian angles or right angles). It can also be defined as a rectangle in which two adjacent sides have equal length.

This instance is a narrower concept derived from shape.

streamline

This instance is a narrower concept derived from line.

surface

This instance has a related Wikipedia page. Short extract:
In mathematics, a surface is a generalization of a plane which needs not be flat – that is, the curvature is not necessarily zero. This is analogous to a curve generalizing a straight line.

surface_viewpoint

This abstraction represents surface as abstracted by viewpoint.

target

This instance is a narrower concept derived from point.

trapezoid

This instance has a related Wikipedia page. Short extract:
In Euclidean geometry, a convex quadrilateral with at least one pair of parallel sides is referred to as a trapezoid () in American and Canadian English but as a trapezium () in English outside North America. The parallel sides are called the bases of the trapezoid and the other two sides are called the legs or the lateral sides (if they are not parallel; otherwise there are two pairs of bases).

This instance is a narrower concept derived from shape.

triangle

This instance has a related Wikipedia page. Short extract:
A triangle is a polygon with three edges and three vertices. It is one of the basic shapes in geometry.

This instance is a narrower concept derived from shape.

trough

This instance has a related Wikipedia page. Short extract:
A crest is the point on a wave with the maximum value of upward displacement within a cycle. A crest is a point on a surface wave where the displacement of the medium is at a maximum.

vertex

This instance has a related Wikipedia page. Short extract:
In geometry, a vertex (plural: vertices or vertexes) is a point where two or more curves, lines, or edges meet. As a consequence of this definition, the point where two lines meet to form an angle and the corners of polygons and polyhedra are vertices.

This instance is a narrower concept derived from point.

viewpoint

This instance has a related Wikipedia page. Short extract:
Two figures in a plane are perspective from a point O if the lines joining corresponding points of the figures all meet at O. Dually, the figures are said to be perspective from a line if the points of intersection of corresponding lines all lie on one line. The proper setting for this concept is in projective geometry where there will be no special cases due to parallel lines since all lines meet.

This instance is a narrower concept derived from point.

wave~sine

This instance has a related Wikipedia page. Short extract:
A sine wave or sinusoid is a mathematical curve that describes a smooth periodic oscillation. A sine wave is a continuous wave.

This instance is a narrower concept derived from curve.

wheelbase

This instance has a related Wikipedia page. Short extract:
In both road and rail vehicles, the wheelbase is the distance between the centers of the front and rear wheels. For road vehicles with more than two axles (e.g.

This instance is a narrower concept derived from line.

wingspan

This instance has a related Wikipedia page. Short extract:
The wingspan (or just span) of a bird or an airplane is the distance from one wingtip to the other wingtip. For example, the Boeing 777-200 has a wingspan of 60.93 metres (199 ft 11 in), and a wandering albatross (Diomedea exulans) caught in 1965 had a wingspan of 3.63 metres (11 ft 11 in), the official record for a living bird.

This instance is a narrower concept derived from line.

x-section

Alternative labels for this instance are: cross-section.

This instance has a related Wikipedia page. Short extract:
In geometry and science, a cross section is the non-empty intersection of a solid body in three-dimensional space with a plane, or the analog in higher-dimensional spaces. Cutting an object into slices creates many parallel cross sections.

x-section~horizontal

This instance is a narrower concept derived from x-section.

This instance has the following attributes:

x-section~horizontal_circle

This abstraction represents x-section%257Ehorizontal as abstracted by circle.

x-section~vertical

This instance is a narrower concept derived from x-section.

This instance has the following attributes:

x-section_parabola

This abstraction represents x-section as abstracted by parabola.

x-section_top

This instance has the following components:

x-section_trapezoid

This abstraction represents x-section as abstracted by trapezoid.

x-section_trapezoid_bottom

This instance has the following components:

x-section_trapezoid_side

This instance has the following components:

x-section_trapezoid_side~left

This instance has the following components:

x-section_trapezoid_side~right

This instance has the following components:

x-section_trapezoid_top

This instance has the following components: