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age 28
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I'm currently a graduate student at University of Washington. I'm interested in combinatorics.


Dec
18
comment If R is an integral domain disprove the RxR is an integral domain?
No, it's not true that $Z_5 \times Z_5 \cong Z_{25}$.
Dec
9
comment Locus of centroid
@MvG: Ah, I misread the problem. I did not see the words "tangent plane".
Dec
9
comment Locus of centroid
This is a two-part problem. First find the intersection with the coordinate axes by setting $x,y = 0$; then $x,z = 0$, then $y,z = 0$. Then use the formula for the centroid of a triangle.
Dec
8
awarded  Caucus
Dec
2
comment Is a proposition about something which doesn't exist true or false?
Ah, I see what you mean. Thanks!
Dec
2
comment Is a proposition about something which doesn't exist true or false?
I'm not sure if I understand why the first statement would be true. I thought that $\{x: x \notin x\}$ would not even be grammatically correct in this context unless you change it to $\{x \in U: x \notin x\}$ for some fixed set $U$. A sentence like $(\forall z)[ (z = \{ x : \in :x\}\}\}\}) \to ( |z| = 1)]$ would not have a truth value, would it?
Nov
25
comment Will it become impossible to learn math?
+1. Perfect answer!
Nov
20
awarded  Tumbleweed
Nov
19
comment Alternating Series , why start at n = 1?
There's no reason. Some people just like the number $1$ better than $0$.
Nov
18
comment Prove that $\mathbb{R}$ is isomorphic to $\mathbb{R}\oplus \mathbb{Q}$ as $\mathbb{Q}$ vector space.
If the dimension for both is the same infinite cardinal number, they are isomorphic.
Nov
18
comment Prove that $\mathbb{R}$ is isomorphic to $\mathbb{R}\oplus \mathbb{Q}$ as $\mathbb{Q}$ vector space.
Vector spaces over a fixed field are isomorphic iff they have the same dimension. What do you know about the dimensions of $\mathbb{R} \oplus \mathbb{Q}$ and $\mathbb{R}$ as vector spaces over $\mathbb{Q}$?
Nov
17
awarded  Good Answer
Nov
13
revised Name for a generalization of Dyck paths, Motzkin paths
added 40 characters in body
Nov
13
asked Name for a generalization of Dyck paths, Motzkin paths
Nov
10
comment What does $e^{\mu}$ mean for a measure $\mu$?
See en.wikipedia.org/wiki/Emu
Nov
9
awarded  Guru
Nov
8
comment Why can we prove mathematically that a formula to solve an (n+5) order polynomial does not exist?
@PerplexingPies: In a sense, yes. You just have to prove that there's a certain property that stays the same when you adjoin $n$th roots of things to your field, but changes if you take the root of a quintic.
Nov
8
comment Why can we prove mathematically that a formula to solve an (n+5) order polynomial does not exist?
@jtbandes: Thanks!
Nov
8
revised Why can we prove mathematically that a formula to solve an (n+5) order polynomial does not exist?
added 5 characters in body
Nov
8
awarded  Good Answer