Brian M. Scott

# 467,107 Reputation

30 today
 +10 4 hours ago upvote $X$ is Hausdorff if and only if the diagonal of $X\times X$ is closed +10 5 hours ago upvote Why is an infinite series not considered an infinite sum of terms? +10 17 hours ago upvote Compact sets of metric spaces are closed?
88 yesterday
 +20 20:42 2 events Proving a theorem in classical propositional logic +20 17:29 2 events Permutation on a set from $\{1, 2, \ldots, 2n\}$ +10 23:44 upvote Does $T_1$ imply Fréchet–Urysohn (every limit point is a limit of some sequence)? +10 22:37 upvote $X$ first-countable, $A \subseteq X$, $x\in X$, then $x \in \text{Int }A\Leftrightarrow$ every sequence in $X$ converging to $x$ is eventually in $A.$ +10 20:49 upvote Axiom of Choice: Family of non-empty sets mutually disjoint or not? +10 14:02 upvote How do you compute the number of reflexive relation? +10 01:20 upvote Proving : Every infinite subset of countable set is countable -2 18:24 downvote Does Pi contain all possible number combinations?
80 2 days ago
 +10 20:59 upvote Example of a function continuous at only one point. +10 19:00 upvote A metric space is separable iff it is second countable +10 17:05 upvote Difference of two graphs +10 13:33 upvote Showing that $\mathbb{R}$ is connected +10 13:33 upvote Compact sets are closed? +10 13:26 upvote Is symmetric group on natural numbers countable? +10 10:36 upvote Why are there $\frac{(2n)!}{2^nn!}$ ways to break $2n$ people into partnerships? +10 08:19 upvote Given a matrix, is there always another matrix which commutes with it?
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