Proving Equivalence and Function Equality in Real Analysis

In summary, the conversation discusses a problem in Real Analysis involving a relation R on a function f and the tasks of proving R is an equivalence relation, showing surjectivity of a function g, and injectivity of a function h. The final task is to prove that f(x) is equal to h(g(x)). The participants have solved the first three tasks but are unsure how to approach the last one. The key concept is that for two functions to be equal, they must send the same element to the same image. The discussion then delves into the definition of injectivity and the connection between f(x) and h(g(x)).
  • #1
SomeRandomGuy
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0
Hey guys, wasn't sure what forum to post this in. So if this is the wrong forum, I apologize. Anyway, I have a problem in Real Analysis that I can't quite get. Here it is:

Let f:A->B and R is a relation on A such that xRy iff f(x) = f(y).
a.) Prove R is an equivalence relation
b.) Show g:A->E is surjective
c.) Show h:E->B is injective
d.) Prove f(x) = h(g(x)).

I solved parts a, b, and c. My problem is part d... I don't even know where to begin. It just doesn't make sense to me when I think about it. Thanks for any help.

EDIT: I just realized I didn't put what E is. E is the equivalence classes on any particular element. So, it's the set of all equivalence classes for this function.
 
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  • #2
For two functions to be equal, they have to send the same element to the same image.
 
  • #3
Galileo said:
For two functions to be equal, they have to send the same element to the same image.

So are we showing that if f(x) = h(g(x)), then g(x) = x? Here is exactly what I have written so far:

"Proof: In order to show that two functions are equal, we must show that for any x in the domain, we will get the same output y in the codomain. So, if f(x) = x, then h(g(x)) = x as well. By the definition if being injective, x = g(x)."

I'm lost from there.
 

FAQ: Proving Equivalence and Function Equality in Real Analysis

What is an equivalence relation?

An equivalence relation is a mathematical concept that describes a relationship between two elements in a set. It is a relation that is reflexive, symmetric, and transitive.

How is an equivalence relation different from other types of relations?

An equivalence relation is different from other types of relations because it must satisfy all three properties - reflexivity, symmetry, and transitivity. Other types of relations may only satisfy one or two of these properties.

Can you give an example of an equivalence relation?

Yes, an example of an equivalence relation is the relation "is equal to" on the set of real numbers. This relation is reflexive (x is equal to itself), symmetric (if x is equal to y, then y is equal to x), and transitive (if x is equal to y and y is equal to z, then x is equal to z).

How are equivalence relations useful?

Equivalence relations are useful in many areas of mathematics, such as group theory, topology, and abstract algebra. They also have applications in computer science, physics, and other fields.

How can I determine if a relation is an equivalence relation?

To determine if a relation is an equivalence relation, you must check if it satisfies all three properties - reflexivity, symmetry, and transitivity. If any of these properties are not satisfied, then the relation is not an equivalence relation.

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