Proving Continuity of g: C0([0, 1]) x [0, 1]-->R

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In summary, the task is to prove the continuity of the map g, which takes a continuous function f on [0, 1] and a point a in [0, 1] and outputs f(a). The Urysohn lemma was initially considered but deemed unfeasible, while the approach of looking at pre-images did not provide any insight. However, the map can be shown to be continuous by directly showing that the difference between f(a) and g(b) can be made small when g is close to f in the supremum norm and a is close to b. The key to this approach is using the fact that f is uniformly continuous on [0, 1], which is possible because [0, 1
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metder
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Homework Statement


Let C0([0, 1]) be the set of continuous functions on the interval [0, 1] with the supremum topology. Prove that the map given by g: C0([0, 1]) x [0, 1]-->R given by g(f, a) = f(a) is continuous.


The Attempt at a Solution


I was originally thinking that maybe I could use the Urysohn lemma to show continuity, but I could not figure out how to make that work in a proof. The simpler method of looking at pre-images of g has also not yielded any insight so far. Any help would be appreciated.
 
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  • #2
Can't you just show it directly? Given f and a you want to make |f(a) - g(b)| small if g is close to f in the sup norm and a is close to b. Try adding and subtracting f(b).
 
  • #3
Ok, you want to show |f1(a1)-f(a)| is close to 0 where f1 is close to f in the supremum topology and a1 is close to a. Did you use that f is uniformly continuous on [0,1] since [0,1] is compact?
 
  • #4
Yeah, you're right. I was over thinking the problem. Thanks for the help.
 

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