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 Yearling
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3h
accepted Simplest way to prove that $e^{ix}$ is an open mapping into $S^1$
1d
comment Simplest way to prove that $e^{ix}$ is an open mapping into $S^1$
how do you choose the $V$ exactly?
2d
asked Simplest way to prove that $e^{ix}$ is an open mapping into $S^1$
Feb
17
accepted The free group given by $\langle a,b:a^2=b^3=e\rangle$ is not abelian.
Feb
17
comment The free group given by $\langle a,b:a^2=b^3=e\rangle$ is not abelian.
@StevenStadnicki Good, So you add another relation to get the $S_3$ and if $G$ were abelian then $S_3$ would be abelian as well after applying the 4th isomorphism theorem. Great, Could you make your comment an answer?
Feb
16
asked The free group given by $\langle a,b:a^2=b^3=e\rangle$ is not abelian.
Feb
13
awarded  Yearling
Jan
29
comment Sequence in an uncountable set of real numbers
@OohAah I see there is a slight difference, but if one changes $B\cap S\text{ is countable}$ by $B\cap S=\{x\}$, isn't the proof the same as Brian's? :)
Jan
29
comment Sequence in an uncountable set of real numbers
@OohAah In this question math.stackexchange.com/questions/310113/… Brian M. Scott actually proves something so much better.
Jan
29
comment Sequence in an uncountable set of real numbers
@OohAah I see it now, I just have to prove that the set of limit points of $A$ is uncountable.
Jan
29
comment Sequence in an uncountable set of real numbers
@OohAah It has to be injective
Jan
29
asked Sequence in an uncountable set of real numbers
Jan
27
comment Measurability Question?
Just to be clear, we are assuming each $f_n:X\to \mathbb{R}$?
Jan
27
comment Can every polynomial be factored into constant and linear complex factors?
isn't it $b_i\in \mathbb{C}$?
Jan
27
answered Let $A$ be any subset of $\mathbb R^{+}$ , then there exist a metric space $(X,d)$ such that $d:X \times X \to A \cup \{0\}$ is a surjection?
Jan
27
comment Functions and continuity proof in real analysis
Write the proof.
Jan
27
comment Trouble showing spans of two bases are equivalent
You should write down the reasoning.
Jan
27
comment Classifying groups of order 60
I don't like where you used presentations and relations, IMHO that's more advanced and it's not treated properly in Dummit and Foote's book. I also remember giving up on this exercise.
Jan
27
comment How to calculate the sum of a general series
@Gabriel Yeah, of course.
Jan
27
answered Trouble showing spans of two bases are equivalent