How Can We Map the Open Interval (0,1) to the Real Line R Using a Homeomorphism?

In summary, the conversation discussed finding a homeomorphism from (0,1) to ℝ. One suggestion was to use a trig function, but the original poster struggled with modifying it. Another suggestion was to use the function x/1-x^2, which maps (-1,1) to ℝ. Finally, a mapping that satisfies these criteria is f(x) = (2x-1)/(1-(2x-1)^2).
  • #1
GridironCPJ
44
0

Homework Statement


Find an explicit homeomorphism from (0,1) to R.


Homework Equations


A homeomorphism from (-1,1) to R is f(x)=tan(pi*x/2).


The Attempt at a Solution


I'm horrible a modifying trig functions. Obviously, to shift by b you add b to (x) and you can change the frequency by including a scalar to pi. I tried f(x)=tax(2pi*(x+1)/2), but this doesn't do the trick.
 
Physics news on Phys.org
  • #2
You are close, you just need to change a few things. Also Do you have to use a trig function? What about x/1-x2, that maps (-1,1) -> ℝ, could you modify that?
 
Last edited:
  • #3
6.28318531 said:
You are close, you just need to change a few things. Also Do you have to use a trig function? What about x/1-x2, that maps (-1,1) -> ℝ, could you modify that?

Consider: ##f: (0,1) → \mathbb{R} \\
\ \ x → \frac{2x-1}{1-(2x-1)^2} ##

This mapping is a Homeomorphism. meaning a Bijection.
could someone specify a metric on (0,1) that defines (the same topology) as the abs. value (i.e. the usual) metric and makes this open interval into a complete set?
 

Related to How Can We Map the Open Interval (0,1) to the Real Line R Using a Homeomorphism?

1. What exactly is a homeomorphism?

A homeomorphism is a mathematical concept that describes a continuous, one-to-one mapping between two topological spaces. In simpler terms, it is a function that preserves the geometric structure of a space, meaning that it maintains the same shape and size of the space even after transformation.

2. How is a homeomorphism from (0,1) to R possible?

A homeomorphism from (0,1) to R is possible because both spaces have the same topological properties, specifically they are both connected and have the same number of dimensions. This means that there is a continuous, one-to-one mapping between the two spaces that preserves their topological structure.

3. Can you provide an example of a homeomorphism from (0,1) to R?

Yes, one example of a homeomorphism from (0,1) to R is the function f(x) = tan((x-0.5)*pi). This function maps all real numbers between 0 and 1 to all real numbers between negative infinity and positive infinity, while preserving the topological structure of both spaces.

4. What are the practical applications of homeomorphisms?

Homeomorphisms have various applications in mathematics, physics, and engineering. They are used to study the properties of different spaces and can be applied to solve problems related to topology, geometry, and differential equations. In physics, homeomorphisms are used to describe the behavior of fields and particles in different spaces.

5. Are all homeomorphisms reversible?

No, not all homeomorphisms are reversible. A homeomorphism is only reversible if it has a continuous inverse function. In other words, a homeomorphism is reversible if it is possible to map the points back to their original positions without any breaks or tears in the space. If a homeomorphism does not have a continuous inverse, it is not reversible.

Similar threads

Replies
6
Views
2K
  • Calculus and Beyond Homework Help
Replies
6
Views
2K
  • Calculus and Beyond Homework Help
Replies
1
Views
2K
  • Calculus and Beyond Homework Help
Replies
1
Views
1K
  • Calculus and Beyond Homework Help
Replies
13
Views
1K
  • Calculus and Beyond Homework Help
Replies
13
Views
5K
  • Calculus and Beyond Homework Help
Replies
4
Views
5K
Replies
1
Views
1K
Replies
1
Views
891
  • Calculus and Beyond Homework Help
Replies
1
Views
5K
Back
Top