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location Providence, RI
age 26
visits member for 3 years, 11 months
seen 4 hours ago

Graduate student in topology.


Jul
3
comment Prove that this affine transformation is a translation
I expect $\phi(P)P$ is the affine hull (line through) the distinct points $\phi(P)$ and $P$. This is why $\phi$ has to have no fixed points.
Jun
26
comment Proving any N x M undirected two dimensional grid is bipartite
This works. It's more concise to say that you are coloring based on the parity of $i+j$.
Jun
26
comment Proving any N x M undirected two dimensional grid is bipartite
You didn't color all the vertices -- only ones where one coordinate is even and the other odd. However, the idea is sound -- coloring based on parity will work here.
Jun
26
comment Question from Munkres algebraic topology section 58: retractions
It would probably good for your question to say what $j_*$ is (I assume the map induced on $\pi_1$, but it would be good to specify.)
Jun
10
answered Shortest path between wikipedia articles
May
23
awarded  Nice Answer
May
21
answered induced sequence exact
May
16
comment Why is this called the orthogonal projection of $u$ on $W$ if $proj_Wu$ is not orthogonal to $u$?
$w_1$ is called an orthogonal projection of $u$ because $w_1$ differs from $u$ by a vector $w_2 = u-w_1$ that is orthogonal to $W$.
May
16
answered Why is this called the orthogonal projection of $u$ on $W$ if $proj_Wu$ is not orthogonal to $u$?
May
16
answered Nuking the Mosquito — ridiculously complicated ways to achieve very simple results
Mar
25
comment Homotopy equivalences
Hint: denote $G = G_f$ to emphasize the dependence of $G$ on $f$. Suppose $f_1,f_2 : X \to Y$ are homotopic. Can you show $G_{f_1} = G_{f_2}$?
Feb
27
comment Topology with one element
I would read "space with only one element" as the space $X = \{*\}$ with the only topology that it can admit.
Feb
27
comment Does $\sin (5x)=5\sin(x)$? Why or why not?
There should be a few values $x$ for which you are familiar with the value $\sin (x)$. (If there aren't, you should learn a few! Having a few examples/computations to keep in mind when thinking about mathematics is vital. I cannot stress this enough.) Does your conjecture hold for these values?
Feb
26
comment Find out, if $a$ lies on a path from $b$ to the root of the tree.
Please specify what you mean by "meet $a$ and then $b$". Depending on how you do this, your algorithm could be correct or incorrect. (You don't want to accept when $a$ and $b$ are on different branches, but you searched $a$'s branch first.) Also the parameter $m$ doesn't exist for this problem.
Feb
26
comment Diagonalise matrix iff eigenvectors independent (True/False)
@Roland Yes :).
Feb
26
comment Diagonalise matrix iff eigenvectors independent (True/False)
Could you clarify what you mean by "eigenvectors are independent"? There are often infinitely many eigenvectors!
Feb
26
reviewed Reject suggested edit on fundamental groups of open subsets of the plane
Feb
26
reviewed Edit suggested edit on Alternating Harmonic Series
Feb
26
revised Alternating Harmonic Series
improved clarity
Feb
26
reviewed Reject suggested edit on What is your favorite application of the Pigeonhole Principle?