109 reputation
6
bio website
location
age
visits member for 1 year, 9 months
seen yesterday

Sep
9
comment Can't find mistake in an easy proof.
@Frunobulax corrected now.
Sep
9
comment How to solve this limits question
For this solution to be correct, you need to show that the original expression is an indeterminate form $\infty/\infty$, which is not completely obvious from the expression as written.
Sep
9
revised Can't find mistake in an easy proof.
fix variable names
Sep
9
suggested suggested edit on Can't find mistake in an easy proof.
Jul
29
awarded  Organizer
Jul
29
revised Separable differentiable equations
replace missing = sign; replace improper-integrals tag with differential-equations tag
Jul
29
suggested suggested edit on Separable differentiable equations
Jun
12
comment Why infinity multiplied by zero was considered zero here?!
While this explains the convergence, it doesn't really answer the OP's question, which was how the ratio test works in this case. The correct answer seems to be this one
Jan
8
comment Pedagogy: How to cure students of the “law of universal linearity”?
More to the point, you have to be able to deal with non-integer exponents.
Jan
8
comment Pedagogy: How to cure students of the “law of universal linearity”?
@JoshuaTaylor How is it different from $3(a+b) = a+b+a+b+a+b = a+a+a+b+b+b = 3a+3b$?
Oct
1
comment Does a red/blue coloring of the infinite subsets of $\mathbb{N}$ necessarily give an infinite monochromatic $M\subset \mathbb{N}$?
Interesting that your answer relies on the cardinality of $\mathbb N$, which the other answers don't. Your answer extends to sets up to size $\mathfrak c$, but not larger. I still like your answer, nevertheless.
Sep
12
awarded  Commentator
Sep
12
comment Is $\{\emptyset\}$ a subset of $\{\{\emptyset\}\}$?
What you are really noticing when you look at the form is that "the set $\{\{\emptyset\}\}$" contains the element $\{\emptyset\}$. $\{\emptyset\}$ is an element of $\{\{\emptyset\}\}$, not a subset of it.
Sep
2
comment Slice of pizza with no crust
In the mathematical formulation, you don't say anywhere that the subsets $A_i$ should be pairwise disjoint (or even almost pairwise disjoint). That would seem to be essential; otherwise the problem might be trivial.
Sep
2
comment Slice of pizza with no crust
I wonder how the mathematical formulation is "more concrete" than the physical description of the problem!
May
24
comment Topology of the power set
Current link is here. (I would have edited it into the answer but the system won't allow me to change just one character.)
May
6
revised Why is it important to study combinatorics?
fixed typo "Brauer" -> "Brouwer"
Mar
8
comment What was the first bit of mathematics that made you realize that math is beautiful? (For children's book)
There was a song about this on Square One TV years ago: "Nine Nine Nine" with the refrain "Nine nine nine, that crazy number nine. Times any number you can find, it all comes back to nine!"
Mar
5
comment What pattern does set theory study?
If mathematics is the science of patterns, does it follow that one branch of mathematics must study one particular pattern?
Mar
4
revised $f_n:D \rightarrow \mathbb{R}$ seq. of functions, $f_n$ continuous, $f_n$ conv. pointwise but not uniformly to $F$, $F$ be continuous?
added subscript n to function name (indicating sequence of functions)