1,104 reputation
626
bio website math.stackexchange.com/users/…
location Antarctica
age 79
visits member for 1 year, 10 months
seen Jan 31 at 5:07

Self-learning mathematics. Many thanks to those who make time to help others on the site.


Jun
17
comment Open sets in $\Bbb{R}^2$ and $\Bbb{R}^3$
So the unit intveral on the x-axis wouldn't be open in $\Bbb{R}^2$ right?
Jun
17
comment Open sets in $\Bbb{R}^2$ and $\Bbb{R}^3$
@Berci Thanks for that
Jun
17
comment Open sets in $\Bbb{R}^2$ and $\Bbb{R}^3$
Yes, but it is still a union of open balls. So in some sense, are open balls the basis of all open sets in $\Bbb{R}^2$?
Jun
17
asked Open sets in $\Bbb{R}^2$ and $\Bbb{R}^3$
Jun
17
comment Topologist's sine curve is connected
Doesn't disconnected mean that there are two disjoint open sets $A$ and $B$ such that the entire set $S$ is equal to $A\cup B$? But when you take your definitions of $A$ and $B$, the union of them is more than what is needed, no?
Jun
17
accepted Clarification on quotient groups
Jun
17
asked Clarification on quotient groups
Jun
17
accepted Congruence relation possible typo?
Jun
17
asked Congruence relation possible typo?
Jun
10
accepted Clarification needed on finding last two digits of $9^{9^9}$
Jun
10
asked Clarification needed on finding last two digits of $9^{9^9}$
Jun
10
accepted Showing a compact metric space has a countable dense subset
Jun
10
accepted Can a group of order $55$ have exactly $20$ elements of order $11$? (Clarification)
Jun
9
asked How to determine the parity of a permutation by its cycle decomposition
Jun
9
revised Can a group of order $55$ have exactly $20$ elements of order $11$? (Clarification)
edited body
Jun
9
asked Can a group of order $55$ have exactly $20$ elements of order $11$? (Clarification)
Jun
9
comment Can a group of order $55$ have exactly $20$ elements of order $11$?
How do you get that there would be 34 elements remaining with order 5?
Jun
9
comment Showing a compact metric space has a countable dense subset
I'm struggling with why $d(x,y)$ has to be less than $1/n$. If the definition of a dense set just requires that another point of $D$ lie in some open neighbourhood of $x \in X$, couldn't it be possible that $y$ is still in $B(x,\epsilon)$ but that the distance between the two points is not less than $1/n$?
Jun
8
accepted Determining whether or not a group has an element of a specific order
Jun
8
accepted What can we say about the order of a group given the order of two elements?