/sci/ - Science & Math

>>12719242
Suppose [math]K[/math] is any compact space and [math]f\colon K\to X[/math] is a compact subset. Conversely, if [math]K \subseteq X[/math] is compact, then it is the image of the inclusion [math]i \colon K\to X[/math]. Combining those, you see that a subset of [math]X[/math] is compact iff it is a continuous image of a compact space, so you can replace the condition with the requirement that compact sets are closed in your space. It is then easier to check whether your space is weak Hausdorff or not.

>>11815553
>I'm not actually that much into logic, just out of necessity. Thanks for thinking of it anyway.
It just reminded me of you when I saw profinite groups and axiomatisability at the same time.

>>11815567
Maybe the king is more into the bishop than into his wife.

>>11575868
>reading
>shitposting
>walking
I would like to start HEMA, but I'm too weak and feel guilty for doing stuff that's not maths.

>>11575898
Cannot be understood by a human being restricted to just one universe.

>>11575909
And 150 to discover you can use Wolfram Alpha.

>>11567761
Don't worry, cat. You will get the basics if you start now. You are going to start now, are you not?

>>11566724
I am pretty sure it's about being canonical. Otherwise you would have to specify the (homotopy class of the) path you are using. Also, you mentioned those maps between fibrations. Given one of those, suppose [math]f\colon B\to B'[/math] would be the map between base spaces, and suppose you have chosen a path class in [math]B'[/math] represented by [math]\gamma'[/colon]. It could happen that there is no [math]\gamma \colon I \to B[/math] such that [math]f\circ \gamma \simeq \gamma'[/math], and so the fixed isomorphism would have to be changed. These are some reasons I can think of, and that anon mentioned orientability. That could also be behind it.