Rudy the Reindeer
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 Apr25 comment Fundamental Group of a finite set with discrete topology @Theo: what's $S^1$? The unit circle? Apr23 comment Homotopy equivalence iff both spaces are deformation retracts @Theo: thanks, that was a typo. I corrected it. Apr23 revised Homotopy equivalence iff both spaces are deformation retracts added 13 characters in body Apr23 comment Simple set exercise seems not so simple Nice answer! Apr23 answered Simple set exercise seems not so simple Apr22 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. Apr22 accepted Why is a finite CW complex compact? Apr21 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! Apr21 asked Why is a finite CW complex compact? Apr21 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. Apr21 comment Homotopy equivalence iff both spaces are deformation retracts @Theo: done! Although, it doesn't seem any more intuitive to me. Apr21 revised Homotopy equivalence iff both spaces are deformation retracts Added detail in response to comment.; added 290 characters in body; edited body Apr19 revised Homotopy equivalence iff both spaces are deformation retracts added 13 characters in body; deleted 5 characters in body Apr19 answered Homotopy equivalence iff both spaces are deformation retracts Apr18 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 : ) Apr17 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. Apr17 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. Apr17 asked Homotopy equivalence iff both spaces are deformation retracts Apr14 accepted Deformation retraction: special case of homotopy equivalence? Apr13 comment Deformation retraction: special case of homotopy equivalence? @Theo: thanks! Yes, see you around ; )