Rudy the Reindeer
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 Dec6 answered Reals constructed from equivalence classes of Cauchy sequences of rationals. Nov30 answered Cardinality of set difference Nov28 comment Cancellation of Direct Product in Grp How do you read $\times$-compact? "product compact"? Did you invent this definition? Nov25 comment $\Bbb{R}^2$ not homeomorphic to $\Bbb{R}^2\setminus \{0\}$ Your question was answered here: math.stackexchange.com/a/30888/5798 Nov24 comment Circle to circle homotopic to the constant map? Ah, great, I understand. I think I can write the proof. Thank you very much for your comment! Nov23 comment Circle to circle homotopic to the constant map? To get the extension do you apply some generalisation to $\mathbb R^2$ of Tietze's extension theorem? Nov23 awarded Popular Question Nov21 awarded Popular Question Nov21 revised Let H be a proper subgroup of G of order prime $p^k$ and $N(H) = \{a \in G|aHa^{-1} = H\}.$Show that $N(H) \neq H.$ edited tags Nov21 revised Using Fourier analysis to show a function is positive typos corrected Nov18 comment Open and closed complex sets Or one of the real parts was meant to be imaginary? Nov18 answered Complex number isomorphic to certain $2\times 2$ matrices? Nov16 comment $\left\{\,f\in L^1[0,1]\,\big\vert\,\int_0^1\lvert f\rvert^2>1\right\}$ is open Wouldn't it be easier to show that the closed unit ball is sequentially closed? Nov16 comment Does a continuous point-wise limit imply uniform convergence? @IlmariKaronen Thank you for your comment! This is a great answer. I hope it gets some more upvotes. Nov16 comment Does a continuous point-wise limit imply uniform convergence? Do I understand correctly: $f_n$ looks like a triangle getting smaller at the base? (piecewise linear function) Nov6 revised About $\infty$-norm on the space of convergent sequences rolled back to a previous revision Nov6 revised About $\infty$-norm on the space of convergent sequences added 1 character in body Nov5 comment Counterexample to the set of all algebraic polynomials being dense in $[0,1]$ I see. So I guess an algebraic polynomial is the same as a polynomial. : ) Nov5 comment Counterexample to the set of all algebraic polynomials being dense in $[0,1]$ What is an algebraic polynomial? Nov5 answered Counterexample to the set of all algebraic polynomials being dense in $[0,1]$