Proving Continuity of F:XxI->I with Continuous Functions

In summary, F:X\times I\to I given by F(x,t)=(1-t)f(x)+tg(x) is a continuous function, as its components f:X\to I and g:X\to I are also continuous. The fact that compositions of continuous functions are continuous, as well as the continuity of sums and products, carries over to any domain. Therefore, there is nothing to show in this case. Looking at specific examples may be helpful in understanding the proof for sums and products being continuous.
  • #1
Euclid
214
0
How can I show that [tex]F:X\times I\to I[/tex] given by [tex]F(x,t)=(1-t)f(x)+tg(x)[/tex] is continuous, given that [tex]f:X\to I[/tex] and [tex]g:X\to I[/tex] are continuous (here I is the unit interval [0,1]). It seems that F is continuous, but I want to show that explicitly. Any help appreciated! X is any topological space.
(I wasn't sure what section to put this in - sorry!)
 
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  • #2
The inverse image of an open set is open...
 
  • #3
what do you know about continuous functions? compositions of them are still continuous, as are sums, products,...
 
  • #4
mathwonk said:
what do you know about continuous functions? compositions of them are still continuous, as are sums, products,...
I'm willing to take that compositions of continuous functions are continuous without proof. I know that sums and products are continuous, but only when the domain is some subset of R^n. Does this carry over to any domain? If that's the case, then there is nothing to show.
I guess my main hangup is determining the inverse image of say (a,b). I'm going to try a specific example and see if that helps.
 
  • #5
think about how you prove sums and products are continuous.

i.e. the addition and multiplication mapp from RxR to R are cotinuous. then if you have two continuous maps f:X-->R and g:X-->R you get one continuous map

(f,g):X-->RxR, and you comkpose with addition or multiplication. so it has nothing to do with the domain of the functions.

i agree there is nothing to do for your problem. but it can only be good to look at examples.
 

1. What is a topological space?

A topological space is a mathematical concept that allows us to study the properties of spaces that are defined by their structure, rather than their specific geometric properties.

2. How is a topological space different from a metric space?

A metric space is a type of topological space, where a distance function (or metric) is defined between points. In a topological space, the notion of distance may not be defined, but the properties of connectedness, continuity, and convergence can still be studied.

3. What are some examples of topological spaces?

Some common examples of topological spaces include the real line, Euclidean spaces, and the surface of a sphere. Other examples include graph structures, networks, and manifolds.

4. What is the importance of topological spaces in scientific research?

Topological spaces have applications in various fields such as physics, biology, and computer science. They provide a powerful framework for analyzing complex systems and understanding their behavior and properties.

5. How are topological spaces studied and visualized?

Topological spaces are studied using various techniques such as algebraic topology, differential topology, and geometric topology. Visualization techniques such as diagrams, graphs, and 3D models can also be used to understand the structure and properties of topological spaces.

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