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1. The Baire category theorem - Aarhus Universitet

1. The Baire category theorem - Aarhus Universitet

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Proof of <strong>Baire</strong>’s <strong>category</strong> <strong>theorem</strong> - continued<br />

<strong>The</strong> proof is now completed as follows; first the case when S is a<br />

locally compact Hausdorff space:<br />

B0 ⊇ B1 ⊇ B2 ⊇ B3 ⊇ ... and each Bk,k ≥ 1, is compact and<br />

non-empty.<br />

It follows that ∞ k=1 Bk = ∅. Since Bk ⊆ Vk−1 for all k, we find<br />

that<br />

∞ ∞<br />

Vk.<br />

k=1<br />

Bk ⊆<br />

But ∞<br />

k=1 Bk ⊆ B0, so we see that<br />

∞<br />

k=1<br />

Bk ⊆<br />

k=0<br />

∞<br />

Vk ∩ B0,<br />

k=1<br />

which was what we wanted to prove.<br />

Klaus Thomsen <strong>1.</strong> <strong>The</strong> <strong>Baire</strong> <strong>category</strong> <strong>theorem</strong>

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