Prove that every regular Lindelöf space is normal

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SUMMARY

Every regular Lindelöf space is proven to be normal based on established theorems in topology. The discussion references Theorem 32.1 from Munkres, which states that every regular space with a countable basis is normal. The proof involves selecting basis elements from a countable subcollection of an open cover, demonstrating the normality of the space. This approach effectively utilizes the properties of Lindelöf spaces to reach the conclusion.

PREREQUISITES
  • Understanding of regular spaces in topology
  • Familiarity with Lindelöf spaces
  • Knowledge of normal spaces and their properties
  • Ability to interpret Theorem 32.1 from Munkres' "Topology"
NEXT STEPS
  • Study the proof of Theorem 32.1 in Munkres' "Topology"
  • Explore the implications of regular spaces with countable bases
  • Research additional properties of Lindelöf spaces
  • Examine examples of normal spaces in topology
USEFUL FOR

Mathematicians, particularly those specializing in topology, students studying advanced topology concepts, and anyone interested in the properties of regular and Lindelöf spaces.

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Homework Statement



So, one needs to prove that every regular Lindelöf space is normal, exactly as the title suggests.

The Attempt at a Solution



I used the following theorem:

Every regular space with a countable basis is normal.

Now, what we need to prove can be proved very similarily to the proof of the theorem above. It's Theorem 32.1., page 200, in Munkres.

What I had in mind:

The proof is exactly the same, with one variation.

Let B be a basis for X. We choose a basis element contained in V for every x in A. Now, for any x in X\A, choose a basis element containing X. This collection forms an open cover for X, and since X is Lindelöf, it has a countable subcollection. So, the subcollection of all the basis elements for the elements of A is countable. Hence, the rest of the proof is the same.

I hope it won't be a problem to open Munkres and look at the proof, since it was too long to type, so I decided to be practical.

Thanks in advance.
 
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As usual, this is a perfect little proof :smile:
 
OK, thanks! It was kind of obvious to use this theorem.
 

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