Composition of continuous maps is continuous

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Homework Help Overview

The discussion revolves around the continuity of the composition of two continuous functions, specifically examining the functions f: D-->R and g: R-->Y, where D, R, and Y are subsets of the plane.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the definitions of continuity and suggest that writing down the definitions could aid in proving the continuity of the composition g o f. Questions are raised regarding the specific definition of continuity being used, and the implications of the inverse function.

Discussion Status

The discussion is active, with participants exploring different definitions of continuity and how they apply to the problem. Some guidance has been offered regarding the use of definitions and the relationship between the functions involved.

Contextual Notes

There is an emphasis on the need for clarity regarding the definitions of continuity, as multiple equivalent definitions exist. Participants are encouraged to consider the implications of these definitions in the context of the problem.

mikki
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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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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.
 
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?
 
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?
 
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
 

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