MathOverflow will be down for maintenance for approximately 3 hours, starting Monday evening (06/24/2013) at approximately 9:00 PM Eastern time (UTC-4).

i707107

1,034
Reputation
932 views
Is this your account?

Registered User 

Name i707107
Member for 1 year
Seen 1 hour ago
Website
Location United States
Age 30
Jun
5
comment Minimal representation of a polynomial as a linear combination of squares
Thanks, I got it now. It can also be done by induction on degree.
Jun
5
comment Minimal representation of a polynomial as a linear combination of squares
Why does $h$ have degree at most $n-1$? I know that it should be $\leq 2n-1$, but how do you get $n-1$?
Jun
2
comment Minimal representation of a polynomial as a linear combination of squares
When it is reducible with $f=uv$, and degree of $u$, $v$ are $n$, then $p=((u+v)/2)^2-((u-v)/2)^2$. But, not sure how to go for other cases.
Jun
2
comment Sums of inverse determinants over matrices
I think the true bound is $S(r)=O(r^2\log r + r^3)$ now.
Jun
2
comment Sums of inverse determinants over matrices
I realized that that estimate was overestimate. This is a counting argument for lattice points, like one uses for Gauss Circle Problem. The number of lattice points inside a convex region is approximated by the area of the region + error term depending on perimeter.
Jun
1
comment Sums of inverse determinants over matrices
Argument seems to work in general, $S(r)=O(r^{n^2-1}\log r)$.
Jun
1
answered Sums of inverse determinants over matrices
Jun
1
comment How does Yitang Zhang use Cauchy’s inequality and Theorem 2 to obtain the error term coming from the $S_2$ sum
Yes, your outline precisely is C-S. But mine is truncation of sums, so I would have $\sum x_iy_i\leq K\sum x_i+K^{-1}\sum x_iy_i^2$, since the first sum on the RHS is upper bound for the sum of terms with $y_i\leq K$, and the second sum on the RHS is for $y_i>K$.
May
31
comment How does Yitang Zhang use Cauchy’s inequality and Theorem 2 to obtain the error term coming from the $S_2$ sum
@GH: Good point! I tried reproducing proof of C-S regarding your comment, but misses a factor of 2. So, this method overestimates than C-S by a factor of 2.
May
31
answered How does Yitang Zhang use Cauchy’s inequality and Theorem 2 to obtain the error term coming from the $S_2$ sum
May
29
comment A technical question related to Zhang’s result of bounded prime gaps
@ericc: Edited. Implemented your correction, and simplified a little. I did not need to have $d=d_0 k$, since what I needed is $d$ having many prime factors.
May
29
revised A technical question related to Zhang’s result of bounded prime gaps
simplified argument, implemented comment by ericc
May
29
comment A technical question related to Zhang’s result of bounded prime gaps
@ericc: Yeah, I missed that. The extra $\tau_{k_0}(d)$ will give extra powers of $\mathcal{L}$ on the numerator. But, my argument still works as you noticed.
May
29
accepted A technical question related to Zhang’s result of bounded prime gaps
May
28
answered A technical question related to Zhang’s result of bounded prime gaps
May
25
accepted Any closed form for series like $F(x)=\Sigma_{i=p}^{\infty}x^p$,p is prime$?
May
24
comment Any closed form for series like $F(x)=\Sigma_{i=p}^{\infty}x^p$,p is prime$?
Hold for series convergent with radius 1. Any series obtained from your setting, will have radius of convergence 1, or infinity. The case when radius of convergence infinity, is only when $r$ has finite decimal expansion.
May
24
comment Full $n$-torsion of elliptic curves and the cyclotomic field of order $n$
Yes. Weil pairing applies to $n$-torsion too.
May
24
comment Any closed form for series like $F(x)=\Sigma_{i=p}^{\infty}x^p$,p is prime$?
As I mentioned in my answer, $r$ can be either rational or irrational. When $r$ is rational, the function $f$ is rational, and when $r$ is irrational, the function $f$ is transcendental.
May
24
comment Any closed form for series like $F(x)=\Sigma_{i=p}^{\infty}x^p$,p is prime$?
This might be better expression: $$\sum_{p\textrm{ prime}} x^p$$
May
24
revised Any closed form for series like $F(x)=\Sigma_{i=p}^{\infty}x^p$,p is prime$?
added 74 characters in body
May
24
answered Any closed form for series like $F(x)=\Sigma_{i=p}^{\infty}x^p$,p is prime$?
May
16
comment Ramification in Division field of Abelian Varieties
Maybe I should have put, $m$ avoids all primes of bad reduction.
May
16
comment Ramification in Division field of Abelian Varieties
Thank you. This is also very clear. So $\mathbb{Q}(E[2])=\mathbb{Q}(\sqrt{d})$, and primes ramify in $\mathbb{Q}$ are precisely the prime divisors of $d$.
May
16
comment Ramification in Division field of Abelian Varieties
Thank you for clear counterexample. I'd like to know what happens when $m$ is a power of $p$.
May
16
asked Ramification in Division field of Abelian Varieties
May
15
comment Sums of uniformly random vectors from the $n$-dimensional unit ball
To clarify: $||v_i||\leq 1$ right? not $||v_i||=1$?
May
9
comment Least prime in an arithmetic progression and the Selberg sieve
What is $\tau$ in the last formula? Is it the "number of divisors" function?
May
8
comment The classifying space of a gauge group
It is also strange that LaTeX is completely working on my iPhone, but not on PC.
May
8
comment Functional equations
Or, are those separate problems?
May
8
comment Functional equations
Putting $x=y=z$, you get $2X^2=1$, and $X^3=1$ where $X=f(x,x)$, which is nonsense.
May
7
comment average involving phi function
I think so too.
May
7
comment average involving phi function
It is also possible to obtain an asymptotic formula with main term $C\frac{1}{\log N}$ for some positive constant $C$.
Apr
20
comment Efficient (divergent) summation for sum of zetas at negative arguments?
See this: wolframalpha.com/input/…
Apr
20
comment Efficient (divergent) summation for sum of zetas at negative arguments?
That must be an error, this function does have limit as $s\rightarrow 0$, and it is $1+\zeta'(0)$.
Apr
19
answered Efficient (divergent) summation for sum of zetas at negative arguments?
Apr
19
comment Efficient (divergent) summation for sum of zetas at negative arguments?
I will write proof of $m=-1$ case as an answer.
Apr
19
comment Efficient (divergent) summation for sum of zetas at negative arguments?
Using that $\zeta'(0)=-\frac{1}{2}\log 2\pi$, I could prove that the approximation you have is correct.
Apr
19
comment Efficient (divergent) summation for sum of zetas at negative arguments?
So, for $m=-1$, did you prove it? or is it just a numerical approximation?
Apr
19
comment When integer polynomials take integer values, does their GCD also take integer values?
Yes, but I am pointing out that the GCD should be considered as UFD element. In particular in $\mathbb{Z}[x]$, the GCD of $P$, and $Q$ is, some integer multiple of OP's definition. For example, GCD of $2x^2$ and $8x^2+4x$ is $2x$.
Apr
8
revised Ordinary Generating Function for Mobius
added 202 characters in body
Apr
8
revised Ordinary Generating Function for Mobius
deleted 204 characters in body
Apr
8
revised Ordinary Generating Function for Mobius
added 198 characters in body; added 12 characters in body
Apr
8
revised Ordinary Generating Function for Mobius
added 386 characters in body
Apr
7
revised Ordinary Generating Function for Mobius
added ; added 30 characters in body; added 11 characters in body; added 10 characters in body; deleted 4 characters in body
Apr
6
awarded  Critic
Apr
3
asked Ordinary Generating Function for Mobius
Mar
22
answered $\prod_{n=1}^{\infty} n{}^{\mu(n)}=\frac{1}{4 \pi ^2}$
Mar
11
answered Expression for the sum of square roots of zeros of a polynomial
Mar
8
revised Invertibility of a certain matrix indexed by the Hamming cube
Added a comment about inverse.