a basis for a topology -- Topology Video 4

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  • เผยแพร่เมื่อ 15 ม.ค. 2025

ความคิดเห็น • 7

  • @theelk801
    @theelk801 วันที่ผ่านมา +1

    can you fix the playlist? the videos are in the wrong order

  • @r.maelstrom4810
    @r.maelstrom4810 2 วันที่ผ่านมา

    First HW exercise is simply doing in reverse, with very little adjustements, the second part of the proof of the claim that 𐌱 = B(f, epsilon) is a basis on C([0,1]).

  • @thedifference2998
    @thedifference2998 2 วันที่ผ่านมา

    Wonderful explanation ❤

  • @r.maelstrom4810
    @r.maelstrom4810 2 วันที่ผ่านมา

    The Axiom of Choice is strong in this one...

  • @AntoshaPushkin
    @AntoshaPushkin 2 วันที่ผ่านมา

    Awesome video!
    Why is the second property of base needed? Is it possible to build a set of elements that satisfies the first property (for all U open and x ∈ U there is a base set b such that x ∈ b ⊆ U) but not the second (for some x ∈ b1 ∩ b2 there is no b3 such that x ∈ b3 ⊆ b1 ∩ b2)?

    • @r.maelstrom4810
      @r.maelstrom4810 2 วันที่ผ่านมา

      15:40

    • @AntoshaPushkin
      @AntoshaPushkin 2 วันที่ผ่านมา

      @@r.maelstrom4810 thanks, I already figured it out and even left a comment under my question. Somehow it got removed by youtube. I misunderstood the definition, I thought that B is a subset of a topology T, but here instead it's defined as just a subset of P(X), and then a topology T is defined as an induced topology. If the definition is B some subset of P(X), then the property is needed. If the definition is B subset of T, then it works automatically by the first property of base plus properties of T