Compact implies feebly compact

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This article gives the statement and possibly, proof, of an implication relation between two topological space properties. That is, it states that every topological space satisfying the first topological space property (i.e., compact space) must also satisfy the second topological space property (i.e., feebly compact space)
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Statement

Any compact space is a feebly compact space.

Definitions used

Compact space

Further information: Compact space

A topological space is termed compact if every open cover of the space has a finite subcover.

Feebly compact space

A topological space is termed feebly compact if every locally finite collection of nonempty open subsets is finite.

Proof

Given: A compact space X, a locally finite collection of nonempty open subsets Vi,iI of X.

To prove: I is finite.

Proof:

  1. There exists a point-indexed open cover Ux,xX of X such that each Ux intersects finitely many Vis: For each point xX, we can find an open subset Ux that works by the definition of locally finite. Putting these together, there exists a point-indexed open cover.
  2. There exists a finite subset A of X such that the Ua,aA, cover X: This follows from the previous step and the definition of compactness.
  3. The size of I is finite: Every Vi,iI, is a nonempty open subset of X, hence it intersects at least one of the Uas. Thus, to count the Vis, it suffices to count the Vis that intersect at least one Ua. For each Ua, the number of Vis intersecting it is finite, and there are finitely many as in A, so the total number is finite.