Understanding Equivalence Classes in the Plane

In summary, the conversation discusses determining equivalence classes for two points on the plane based on a given equation. The equation results in parabolas as equivalence classes, which can be visualized by adding a third coordinate. The conversation concludes with gratitude and a suggestion for a point system for thanking users on Physics Forums.
  • #1
QuantumP7
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Homework Statement


Define two points [tex](x_{0}, y_{0}) [/tex] and [tex] (x_{1}, y_{1})[/tex] of the plane to be equivalent if [tex]y_{0} - x_{0} ^2 = y_{1} -x_{1}^2[/tex]. Check that this is an equivalence relation and describe the equivalence classes.


Homework Equations





The Attempt at a Solution

I can understand how to check that it is an equivalence relation. But apparently, the equivalence classes are the sets of points on the parabolas [tex]y = x^2 + c[/tex]. I don't really understand why? Would the equivalence classes not be all z such that [tex] y - x^2[/tex], which would be a paraboloid?
 
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  • #2
Equivalence classes are each subsets of the plane. Each equivalence class is a parabola. By adding in the z coordinate you are just layering the equivalence classes vertically -- if you project downward onto the plane, you get a picture of the equivalence classes all in the plane.
 
  • #3
Wow!

Thank you SO much! I get it now!

Physics Forums need some kind of point system for thanks.
 

What are equivalence classes?

Equivalence classes are a fundamental concept in mathematics and computer science. They are sets that group together objects that are considered equivalent based on a given relation or property. This means that all the objects within an equivalence class are considered equivalent to one another, but different from objects in other equivalence classes.

How do you determine equivalence classes?

To determine equivalence classes, you must define a relation or property that determines when two objects are equivalent. Then, you can group together all the objects that satisfy this relation or property into their own equivalence class. This process can be applied to any set of objects, as long as a well-defined relation or property is established.

What is the importance of equivalence classes?

Equivalence classes are important because they allow us to simplify complex systems and problems by grouping together objects that share a common property. This helps us better understand and analyze these systems, and can also aid in problem-solving and decision-making processes.

How are equivalence classes used in mathematics?

Equivalence classes are used in a variety of mathematical fields, including set theory, abstract algebra, and topology. They are particularly useful in understanding and defining mathematical structures, such as groups, rings, and topological spaces. Equivalence classes also play a crucial role in mathematical proofs and theorems.

Can you give an example of equivalence classes in real life?

One example of equivalence classes in real life is the concept of currency. In a given country, all the different types of currency (e.g. coins and bills) are considered equivalent to one another in terms of their value. This means that all the coins of a certain denomination, for example, can be grouped into one equivalence class, and all the bills of a certain denomination can be grouped into another equivalence class.

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