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Some authors call a function F : X → 2 Y a set-valued function only if it satisfies the additional requirement that F(x) is not empty for every x ∈ X; this article does not require this. Definition and notation: If F : X → 2 Y is a set-valued function in a set Y then the graph of F is the set Gr F := { (x, y) ∈ X × Y : y ∈ F(x) }.
For example, in the simple equation 3 + 2y = 8y, both sides actually contain 2y (because 8y is the same as 2y + 6y). Therefore, the 2y on both sides can be cancelled out, leaving 3 = 6y, or y = 0.5. This is equivalent to subtracting 2y from both sides. At times, cancelling out can introduce limited changes or extra solutions to an equation. For ...
The unit circle can be specified as the level curve f(x, y) = 1 of the function f(x, y) = x 2 + y 2. Around point A, y can be expressed as a function y(x). In this example this function can be written explicitly as () =; in many cases no such explicit expression exists, but one can still refer to the implicit function y(x). No such function ...
The image of a function f(x 1, x 2, …, x n) is the set of all values of f when the n-tuple (x 1, x 2, …, x n) runs in the whole domain of f.For a continuous (see below for a definition) real-valued function which has a connected domain, the image is either an interval or a single value.
Given a function: from a set X (the domain) to a set Y (the codomain), the graph of the function is the set [4] = {(, ()):}, which is a subset of the Cartesian product.In the definition of a function in terms of set theory, it is common to identify a function with its graph, although, formally, a function is formed by the triple consisting of its domain, its codomain and its graph.
We can treat arctan as a single-valued function by restricting the domain of tan x to − π /2 < x < π /2 – a domain over which tan x is monotonically increasing. Thus, the range of arctan(x) becomes − π /2 < y < π /2. These values from a restricted domain are called principal values. The antiderivative can be considered as a ...
The unit circle can be defined implicitly as the set of points (x, y) satisfying x 2 + y 2 = 1. Around point A, y can be expressed as an implicit function y(x). (Unlike in many cases, here this function can be made explicit as g 1 (x) = √ 1 − x 2.) No such function exists around point B, where the tangent space is vertical.
The minimal (a,b)-separators also form an algebraic structure: For two fixed vertices a and b of a given graph G, an (a,b)-separator S can be regarded as a predecessor of another (a,b)-separator T, if every path from a to b meets S before it meets T. More rigorously, the predecessor relation is defined as follows: Let S and T be two (a,b ...