Point Set Topology: Non-Trivial Facts Beyond Uryshon's Lemma

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    Point Set Topology
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Discussion Overview

The discussion revolves around identifying non-trivial facts in point set topology beyond Uryshon's lemma. Participants explore various theorems and concepts that they consider significant within the field.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification

Main Points Raised

  • Some participants propose that Tychonoff's theorem is a notable non-trivial fact in point set topology.
  • Others mention Tietze's extension theorem and Čech-Stone compactifications as important contributions.
  • A participant highlights space-filling curves and the theorem stating that every compact metric space is the image of the Cantor set.
  • Another participant brings up the Siefert-Van Kampen theorem, noting its connection to algebraic topology.
  • There is a suggestion regarding the existence of a partition of unity for certain spaces.
  • Additionally, a participant mentions Stone's theorem about metric spaces being paracompact.

Areas of Agreement / Disagreement

Participants generally agree on the significance of various theorems in point set topology, but multiple competing views on what constitutes non-trivial facts remain, leaving the discussion unresolved.

Contextual Notes

Some contributions may depend on specific definitions or interpretations of non-triviality, and the scope of what is included as a non-trivial fact is not fully established.

facenian
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Hello
I am curious about this. Uryshon' s lemma is also known as "the first non-trivial fact of point set topology", what are the others non-trivial facts of point set topology?
I suppose Tychonoff' s theorem is another one.
 
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I would say things like Tychonoffs theorem, Tietze's extension theorem, Cech-Stone compactifications,...
 
Not to forget space-filling curves and the theorem that says that every compact metric space is the image of the Cantor set. Also, the Siefert-Van Kampen theorem, but that's algebraic topology...
 
Perhaps the existence of a partition of unity for certain spaces.
 
Yeah, that to. And also Stones theorem that metric spaces are paracompact...
 
Thank you guys
 

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