Isaac Solomon
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 1d comment Definable over $(\mathbb{R}, +, \cdot)$ Where is the existential quantifier for $v_{1}$ in (c)? 2d comment Free action of a discrete group gives a covering space What if $\mathbb{Z}$ acts on $S^1$ via irrational rotations? The quotient is compact but not Hausdorff. May 1 awarded Nice Answer Apr 19 comment Show that $f$ is identically zero if and only if $\displaystyle \int_{a}^b f(x)dx = 0$ Yeah, I just edited that back in. Thanks for pointing this out! Apr 19 revised Show that $f$ is identically zero if and only if $\displaystyle \int_{a}^b f(x)dx = 0$ added 142 characters in body Apr 19 comment Show that $f$ is identically zero if and only if $\displaystyle \int_{a}^b f(x)dx = 0$ Oh right, I misread the assumption. Apr 19 answered Show that $f$ is identically zero if and only if $\displaystyle \int_{a}^b f(x)dx = 0$ Apr 18 answered Why is a line not quasi-isometric to a plane? Apr 12 answered Orientable on almost complex manifold Apr 7 answered Why is the absolute of the union of the differences of sets greater than the absolute of the difference between the unions? Apr 7 answered The set X is the complex numbers in cofinite topology Apr 7 answered Why if $p (x_1, \dots, x_n)$ is polynomial on $\mathbb{R}^n$, then $p (x) \neq 0$ is satisfied by open dense set? Apr 1 comment Does it make sense to define a “metric topological space” $(M, d, \tau)$ They are both topological notions, but in general they do not coincide. There are spaces which can be sequentially compact but not covering compact, and vice-versa. However, for metric spaces they are the same. In any event, sequential compactness is just about covergence of sequences, it doesn't require us to define a metric. Apr 1 answered Does it make sense to define a “metric topological space” $(M, d, \tau)$ Mar 12 answered Unique way to show $S^n$, $n \geq 2$ is simply connected. Mar 10 comment Can $S^n$ be defined without reference to an $n+1$ dimensional embedding space? Oh, oops. Yeah, I corrected that. Mar 10 revised Can $S^n$ be defined without reference to an $n+1$ dimensional embedding space? added 26 characters in body Mar 9 answered Can $S^n$ be defined without reference to an $n+1$ dimensional embedding space? Jan 26 awarded Famous Question Jan 23 awarded Good Answer