Thomas Belulovich

Providence, RI

math.brown.edu/~thobel

Age: 26

Aug
5
awarded Yearling
Aug
5
awarded Yearling
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
Jun
7
awarded Popular Question
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 Edit suggested edit on Alternating Harmonic Series
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