projection

projection (prəˈdʒɛkʃən)
—n
1.	the act of projecting or the state of being projected
2.	an object or part that juts out
3.	See map projection
4.	the representation of a line, figure, or solid on a given plane as it would be seen from a particular direction or in accordance with an accepted set of rules
5.	a scheme or plan
6.	a prediction based on known evidence and observations
7.	a.  the process of showing film on a screen
	b.  the image or images shown
8.	psychol
	a.  the belief, esp in children, that others share one's subjective mental life
	b.  See also defence mechanism the process of projecting one's own hidden desires and impulses
9.	the mixing by alchemists of powdered philosopher's stone with molten base metals in order to transmute them into gold
pro'jectional
—adj

projection pro·jec·tion (prə-jěk'shən)
n.

1. The act of projecting or the condition of being projected.

2. The attribution of one's own attitudes, feelings, or suppositions to others.

3. The attribution of one's own attitudes, feelings, or desires to someone or something as a naive or unconscious defense against anxiety or guilt.

4. The localization of visual impressions to a point in space relative to the person who is doing the viewing: straight ahead, right, left, above, or below.

5. Any of the systems of nerve fibers by which a group of nerve cells discharges its nerve impulses to one or more other cell groups.

projection   (prə-jěk'shən)  Pronunciation Key  The image of a geometric figure reproduced on a line, plane, or surface. A system of intersecting lines, such as the grid of a map, on which part or all of the globe or another spherical surface is represented as a plane surface. See more at azimuthal projection, conic projection, cylindrical projection.

projection definition

theory
In domain theory, a function, f, which is (a) idempotent, i.e. f(f(x))=f(x) and (b) whose result is no more defined than its argument. E.g. F(x)=bottom or F(x)=x.
In reduction systems, a function which returns some component of its argument. E.g. head, tail, \ (x,y) . x. In a graph reduction system the function can just return a pointer to part of its argument and does not need to build any new graph.
(1997-01-29)

projection

in cartography, systematic representation on a flat surface of features of a curved surface, as that of the Earth. Such a representation presents an obvious problem but one that did not disturb ancient or medieval cartographers. Only when the voyages of exploration stimulated production of maps showing entire oceans, hemispheres, and the whole Earth did the question of projection come to the fore. Mercator produced the simplest and, for its purposes, the best solution by in effect converting the spherical Earth into a cylinder with the open ends at the poles; this cylinder was then opened to form a plane surface. East-west and north-south directions could be represented with fidelity, and the distortions in size became gross only near the polar regions (rendering Greenland, for example, disproportionately large). The Mercator projection is still widely used, especially when north-south dimensions are of chief importance. Many other projections are used, for example, the conic projection, drawn from a point directly above the North or South Pole. All projections involve some degree of distortion, and those showing the entire Earth involve a large degree

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