Arthur Fischer
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 Apr17 revised Order topology is regular and not normal MathJax for formatting ain't good Apr17 comment Is $2^{\aleph_0} = \aleph_1$? You might want to be a bit more explicit about what $\mathfrak{c}$ can be. As currently worded it could be interpreted to mean that $\mathfrak{c}$ can be any aleph at least $\aleph_1$. But, of course, $\mathfrak{c}$ cannot be $\aleph_\omega$ or $\aleph_{\omega^\omega}$, although it can be $\aleph_{\omega+1}$ or $\aleph_{\omega_1}$. Apr17 revised Show that a surjective function from $X$ to $J$ does not exist (with a twist!!) no more hint Apr17 revised Metric spaces are completely normal added 62 characters in body; edited tags; edited title Apr17 revised Countable dense subsets of $\mathbb R$ are homeomorphic added 34 characters in body; edited title Apr17 comment Existence of a closed and open set in 0-dimensional Hausdorff space The question is not an exact duplicate, but Alex Ravsky's posted answer is explicitly for this more general situation. Apr17 revised Verify that $\alpha(a)\neq2$ for all $a$ where $\alpha(x): (2x + 1)/(x + 2)$ Just changed this answer to match the original question (exact same logic). Apr17 revised Verify that $\alpha(a)\neq2$ for all $a$ where $\alpha(x): (2x + 1)/(x + 2)$ added 96 characters in body; edited title Apr17 revised Verify that $\alpha(a)\neq2$ for all $a$ where $\alpha(x): (2x + 1)/(x + 2)$ rolled back to a previous revision Apr17 revised Verify that $\alpha(a)\neq2$ for all $a$ where $\alpha(x): (2x + 1)/(x + 2)$ rolled back to a previous revision Apr17 revised In a Hausdorff space the intersection of a chain of compact connected subspaces is compact and connected Tidy it up, make some corrections to some of the assertions (as pointed out in comments) Apr17 revised Is $\left(\bigcup_{i=1}^{\infty}A_i\right)^{o} = \bigcup_{i=1}^{\infty}A_i^{o}$? edited title Apr17 revised Is $\left(\bigcap_{i=1}^{\infty}A_i\right)^{o} = \bigcap_{i=1}^{\infty}A_i^{o}$? edited title Apr16 comment informal semantics regarding CH and AC @DavidHolden: Not sure about Cohen, but Gödel was a Platonist who really thought that CH was false. At one point he thought that the theory of large cardinals would produce the evidence to show this. (We now know that this was not to be.) There was also a "Gödel programme" to search for new axioms for set theory ("axiom" here in the classical meaning of an obviously true statement about the concept at hand) which would resolve CH. In some sense this search continues with the work of Hugh Woodin, Sy Friedman, and others. Apr16 revised An example of a linear system that has a straight-line solution $[x(t), y(t)]$ such that $x(0) = -1$ and $y(t) = 2x(t)$ for all $t$ tried to incorporate info from other copy of this question: http://math.stackexchange.com/q/1236927 Apr16 comment Spaces in which the closure of every countable subset does not include an uncountable closed discrete subset Note that every discrete space has this property. Is there some reason you are looking at such spaces? Apr16 revised Spaces in which the closure of every countable subset does not include an uncountable closed discrete subset tidied it up Apr16 revised Breaking the AC barrier using Kelley-Morse set theory attempt to tidy this up, include links, etc. Apr16 comment Proving that the gamma function is a certain limit Comments are not for extended discussion; this conversation has been moved to chat. Apr16 revised Expected values of a dice game with a 30-sided die and a 20-sided die. general clean-up