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Apr
25
comment Fundamental Group of a finite set with discrete topology
@Theo: what's $S^1$? The unit circle?
Apr
23
comment Homotopy equivalence iff both spaces are deformation retracts
@Theo: thanks, that was a typo. I corrected it.
Apr
23
revised Homotopy equivalence iff both spaces are deformation retracts
added 13 characters in body
Apr
23
comment Simple set exercise seems not so simple
Nice answer!
Apr
23
answered Simple set exercise seems not so simple
Apr
22
comment Why is a finite CW complex compact?
@Dylan: Thanks. I think now I understand. A cell is the interior of a closed disk. @Dylan: Did you mean to write "...is to glue a disk along its boundary..."? Because if a cell is open then it doesn't have a boundary.
Apr
22
accepted Why is a finite CW complex compact?
Apr
21
comment Why is a finite CW complex compact?
But on page 5 he writes "open $n$-disk" where he explains how to construct a CW complex in step (2). He is attaching open disks!
Apr
21
asked Why is a finite CW complex compact?
Apr
21
comment Homotopy equivalence iff both spaces are deformation retracts
@Chris: thanks, but that uses "the preceding corollary". I'm going to read that but for now I needed something that doesn't use things that I don't know yet.
Apr
21
comment Homotopy equivalence iff both spaces are deformation retracts
@Theo: done! Although, it doesn't seem any more intuitive to me.
Apr
21
revised Homotopy equivalence iff both spaces are deformation retracts
Added detail in response to comment.; added 290 characters in body; edited body
Apr
19
revised Homotopy equivalence iff both spaces are deformation retracts
added 13 characters in body; deleted 5 characters in body
Apr
19
answered Homotopy equivalence iff both spaces are deformation retracts
Apr
18
comment Homotopy equivalence iff both spaces are deformation retracts
@Akhil: no need to apologise. Seeing a high-level proof is also useful to me. As for my background: there was no way you could've known and I'm surprised at @Theo's good memory : )
Apr
17
comment Homotopy equivalence iff both spaces are deformation retracts
@Theo: Thanks, that's right. I gave him an upvote and started to look up the funny words. "Cofibration" seems to be another way of saying "satisfies the homotopy extension property". Now I try and see if I can understand the rest.
Apr
17
comment Homotopy equivalence iff both spaces are deformation retracts
@Aaron: Are you sure? I just looked up what it means but what I'm trying to prove doesn't need CW complexes.
Apr
17
asked Homotopy equivalence iff both spaces are deformation retracts
Apr
14
accepted Deformation retraction: special case of homotopy equivalence?
Apr
13
comment Deformation retraction: special case of homotopy equivalence?
@Theo: thanks! Yes, see you around ; )