„Carnap calls such concepts as point, straight line, etc., which are given by implicit definitions, improper concepts. Their peculiarity rests on the fact that they do not characterize a thing by its properties, but by its relation to other things. Consider for example the concept of the last car of a train. Whether or not a particular car falls under this description does not depend on its properties but on its position relative to other cars. We could therefore speak of relative concepts, but would have to extend the meaning of this term to apply not only to relations but also to the elements of the relations.“

—  Hans Reichenbach, The Philosophy of Space and Time (1928, tr. 1957)
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Hans Reichenbach
professor académico alemão 1891 - 1953

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„Let us begin by observing that the word "system" is almost never used by itself; it is generally accompanied by an adjective or other modifier: physical system; biological system; social system; economic system; axiom system; religious system; and even "general" system. This usage suggests that, when confronted by a system of any kind, certain of its properties are to be subsumed under the adjective, and other properties are subsumed under the "system," while still others may depend essentially on both. The adjective describes what is special or particular; i. e., it refers to the specific "thinghood" of the system; the "system" describes those properties which are independent of this specific "thinghood."
This observation immediately suggests a close parallel between the concept of a system and the development of the mathematical concept of a set. Given any specific aggregate of things; e. g., five oranges, three sticks, five fingers, there are some properties of the aggregate which depend on the specific nature of the things of which the aggregate is composed. There are others which are totally independent of this and depend only on the "set-ness" of the aggregate. The most prominent of these is what we can call the cardinality of the aggregate…
It should now be clear that system hood is related to thinghood in much the same way as set-ness is related to thinghood. Likewise, what we generally call system properties are related to systemhood in the same way as cardinality is related to set-ness. But systemhood is different from both set-ness and from thinghood; it is an independent category.“

—  Robert Rosen American theoretical biologist 1934 - 1998
"Some comments on systems and system theory," (1986), p. 1-2 as quoted in George Klir (2001) Facets of Systems Science, p. 4

„Objects do not depend on the concepts we have of them.“

—  Carlos Gershenson Mexican researcher 1978
Artificial Societies of Intelligent Agents (2001), p. 5

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„Let us imagine that from any given point the system of shortest lines going out from it is constructed; the position of an arbitrary point may then be determined by the initial direction of the geodesic in which it lies, and by its distance measured along that line from the origin. It can therefore be expressed in terms of the ratios dx0 of the quantities dx in this geodesic, and of the length s of this line. …the square of the line-element is \sum (dx)^2 for infinitesimal values of the x, but the term of next order in it is equal to a homogeneous function of the second order… an infinitesimal, therefore, of the fourth order; so that we obtain a finite quantity on dividing this by the square of the infinitesimal triangle, whose vertices are (0,0,0,…), (x1, x2, x3,…), (dx1, dx2, dx3,…). This quantity retains the same value so long as… the two geodesics from 0 to x and from 0 to dx remain in the same surface-element; it depends therefore only on place and direction. It is obviously zero when the manifold represented is flat, i. e., when the squared line-element is reducible to \sum (dx)^2, and may therefore be regarded as the measure of the deviation of the manifoldness from flatness at the given point in the given surface-direction. Multiplied by -¾ it becomes equal to the quantity which Privy Councillor Gauss has called the total curvature of a surface. …The measure-relations of a manifoldness in which the line-element is the square root of a quadric differential may be expressed in a manner wholly independent of the choice of independent variables. A method entirely similar may for this purpose be applied also to the manifoldness in which the line-element has a less simple expression, e. g., the fourth root of a quartic differential. In this case the line-element, generally speaking, is no longer reducible to the form of the square root of a sum of squares, and therefore the deviation from flatness in the squared line-element is an infinitesimal of the second order, while in those manifoldnesses it was of the fourth order. This property of the last-named continua may thus be called flatness of the smallest parts. The most important property of these continua for our present purpose, for whose sake alone they are here investigated, is that the relations of the twofold ones may be geometrically represented by surfaces, and of the morefold ones may be reduced to those of the surfaces included in them…“

—  Bernhard Riemann German mathematician 1826 - 1866
On the Hypotheses which lie at the Bases of Geometry (1873)

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„Jobs: Most people have no concept of how an automatic transmission works, yet they know how to drive a car. You don't have to study physics to understand the laws of motion to drive a car. You don't have to understand any of this stuff to use Macintosh.“

—  Steve Jobs American entrepreneur and co-founder of Apple Inc. 1955 - 2011
1980s, Steve Jobs, Playboy, Feb 1985, by Philip Elmer-Dewitt, “Steve-Jobs The Playboy Interview” http://fortune.com/2010/11/20/steve-jobs-the-playboy-interview/, Fortune.com, November 20, 2010.

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„Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Etiam egestas wisi a erat. Morbi imperdiet, mauris ac auctor dictum.“