• Semjaza@lemmynsfw.com
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    7 days ago

    A CD is clearly homotopic to a torus, though…

    And the walls of a straw do have thickness…
    A straw goes:

    Gas - solid - gas - solid - gas

    • iAvicenna@lemmy.world
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      7 days ago

      If solid torus yes, if just the regular torus (surface of the solid torus) no. CD is homotopic to a circle and so is a solid torus.

      • Semjaza@lemmynsfw.com
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        7 days ago

        OK, that’s my ignorance. I didn’t realise toruses were usually hollow.

        Thank you for letting me know, you’re right and I’ve learnt something.