Mapping and inverse mapping of open sets and their complements

In summary, the conversation discusses the relationship between a function f and its inverse mapping f^{-1}. It is concluded that for f(E^c) and f(E)^c to be equal, f must be injective, and for f^{-1} to be defined, f must be bijective.
  • #1
alyafey22
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Assume that \(\displaystyle f: E \to Y \,\,\, , E \subset X\) then can we say that \(\displaystyle f(E^c)=f(E)^c\) what about the inverse mapping \(\displaystyle f^{-1}: V \to X \,\,\, , V\subset Y\) do we have to have some restrictions on f and its inverse ? My immediate answer is that we have to have a bijection in order to conclude that but I am not sure.
 
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  • #2
ZaidAlyafey said:
Assume that \(\displaystyle f: E \to Y \,\,\, , E \subset X\) then can we say that \(\displaystyle f(E^c)=f(E)^c\) what about the inverse mapping \(\displaystyle f^{-1}: V \to X \,\,\, , V\subset Y\) do we have to have some restrictions on f and its inverse ? My immediate answer is that we have to have a bijection in order to conclude that but I am not sure.

If we have \(\displaystyle f: E \to Y,\ E \subset X\) then can we say that \(\displaystyle f(E^c)=\varnothing\), since f is not defined for any element that is not in E, while $f(E)^c = Y \backslash f(E)$, which is not necessarily empty.

The inverse as you define it, is only defined if f is injective.
That is since each element in the domain of $f^{-1}$ must have exactly 1 image.
Or put otherwise, the mapping between E and V must be bijective.
 

Related to Mapping and inverse mapping of open sets and their complements

1. What is the purpose of mapping and inverse mapping of open sets and their complements?

Mapping and inverse mapping of open sets and their complements is used in topology to understand the relationships between different sets and their corresponding inverse sets. It helps to determine the continuity and convergence of functions.

2. How is mapping and inverse mapping of open sets and their complements used in real-world applications?

This concept is commonly used in fields such as engineering, physics, and economics to analyze the behavior of systems and predict future outcomes. It also has applications in computer science, such as in data compression and pattern recognition.

3. Can you give an example of mapping and inverse mapping of open sets and their complements?

One example is the mapping of a circle onto a square, where the circle is the open set and the square is its complement. The inverse mapping would then transform the square back into a circle.

4. How does the concept of continuity relate to mapping and inverse mapping of open sets and their complements?

Continuity is a fundamental aspect of topology and is closely related to mapping and inverse mapping. A function is continuous if its inverse mapping takes open sets to open sets, meaning it maintains the same topological structure.

5. What are some common misconceptions about mapping and inverse mapping of open sets and their complements?

One common misconception is that the concept is limited to geometry or visual representations. In reality, mapping and inverse mapping can be applied to any type of set, including abstract and infinite sets. Another misconception is that the inverse of a mapping must also be a function, when in fact it may only be a relation.

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