Is the Graph of a Continuous Map from X to Y a Closed Subset of XxY?

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Homework Help Overview

The discussion revolves around proving that the graph of a continuous map from a topological space X to a Hausdorff space Y is a closed subset of the product space XxY. Participants are exploring the relationship between open and closed sets in this context.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants are considering the definitions of closed and open sets, particularly in relation to the graph L of the function f. There is an emphasis on understanding what it means for a set to be closed and the implications of its complement being open. Some participants express uncertainty about the connection to the proof in Banach space.

Discussion Status

The discussion is ongoing, with participants sharing thoughts on the nature of closed sets and exploring various approaches. Some guidance has been offered regarding the relationship between closed and open sets, but no consensus or definitive direction has emerged yet.

Contextual Notes

Participants mention constraints such as impending deadlines for the assignment, which may influence their exploration of the problem.

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Homework Statement


Let f:X->Y be a cts map from a topological space X to a Hausdorff space Y. Prove that the graph L={(x,y) in XxY: y=f(x)} is a closed subset of XxY.

The Attempt at a Solution


Hausdorff space are linked with open sets so how do you prove closeness in XxY?
 
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This is not important but since open sets are linked to closed sets, then anything to do with closed sets has some relation with open sets. You understand that a set is open if and only if its complement is closed?

So, start with L. What does it mean to be closed? There are many things to try, so write a few of them down and think about it for a while (perhaps a day or so, if need be - answers don't just magically appear instantly in people's minds).
 
matt grime said:
There are many things to try, so write a few of them down and think about it for a while (perhaps a day or so, if need be - answers don't just magically appear instantly in people's minds).

If only the assignment is not due tomorrow morning.:rolleyes:
 
L is closed if and only if its complement is open. Suppose that the complement is not open. What does that mean?
 
matt grime said:
L is closed if and only if its complement is open. Suppose that the complement is not open. What does that mean?

Can you give more hint?

Why can't we use the proof in Banach space in the following link?
http://myyn.org/m/article/proof-of-closed-graph-theorem/
 
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