Composition of continuous maps is continuous

In summary, the composition g o f is a continuous transformation if f and g are both continuous transformations and the inverse of f composed with the inverse of g is also a continuous transformation. This can be proven by using the definition of continuity, which states that for every open set U in the range, the inverse of f composed with the inverse of g must also be an open set in the domain.
  • #1
mikki
7
0
Suppose that f: D-->R and g: R-->Y are two continuous transfromations, where D, R, and Y are subsets of the plane. Show that the composition
g o f is a continuous transformation.
 
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  • #2
mikki said:
Show that the composition g o f is a continuous transformation.

Who are you talking to? Show some work if you want some help.
 
  • #3
mikki said:
Suppose that f: D-->R and g: R-->Y are two continuous transfromations, where D, R, and Y are subsets of the plane. Show that the composition
g o f is a continuous transformation.

it doesn't take much to prove that. if you just write down the definitions i think you'll have done half the work. what have you tried so far?
 
  • #4
What definition of "continuous" are you using? There are several equivalent ones. The most common is "f is continuous if and only if for every open set U in the range, f-1(U) is an open set in the domain. What is (gof)-1?
 
  • #5
HallsofIvy said:
What definition of "continuous" are you using? There are several equivalent ones. The most common is "f is continuous if and only if for every open set U in the range, f-1(U) is an open set in the domain. What is (gof)-1?

thats what i was getting at. consider f-1[g-1(U)] & it's pretty much done
 

Related to Composition of continuous maps is continuous

1. What is the definition of composition of continuous maps?

The composition of continuous maps is the process of combining two or more continuous functions to create a new continuous function. It is denoted as f ∘ g, where f and g are both continuous functions.

2. Why is the composition of continuous maps important?

The composition of continuous maps is important because it allows us to create more complex and meaningful functions by combining simpler functions. It also plays a crucial role in many mathematical proofs and applications.

3. How do you prove that the composition of continuous maps is continuous?

To prove that the composition of continuous maps is continuous, we need to show that for any two continuous functions f and g, the composition function f ∘ g is also continuous. This can be done using the epsilon-delta definition of continuity or by using the intermediate value theorem.

4. Can the composition of discontinuous maps be continuous?

No, the composition of discontinuous maps cannot be continuous. In order for the composition of two functions to be continuous, both functions must be continuous. If even one of the functions is discontinuous, the composition will also be discontinuous.

5. Are there any exceptions to the composition of continuous maps being continuous?

Yes, there are some cases where the composition of continuous maps may not be continuous. For example, if the domain of the first function does not overlap with the range of the second function, the composition may not be defined or continuous. Additionally, if the functions have a removable or jump discontinuity at the point of composition, the resulting composition may still be continuous.

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