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Apr
6
comment Why are additional constraint and penalty term equivalent in ridge regression?
Can you briefly summarize the paper (since the journal version has some pages)?
Apr
6
comment Why are additional constraint and penalty term equivalent in ridge regression?
If $\alpha=0$, does it mean the corresponding $c$ can be any non-negative number, according to the second KKT condition?
Mar
20
revised How to compute/ find cancellation for the second group cohomology $H^2(G,A)$?
Added a missing $ in the title
Mar
20
suggested approved edit on How to compute/ find cancellation for the second group cohomology $H^2(G,A)$?
Jan
27
comment Does Euclidean division not work for general polynomials?
ED implies PID. But only polynomials of one variable can form a PID. So no.
Dec
9
awarded  Excavator
Dec
9
revised Does the curvature determine the metric?
log -> \log, cos -> \cos, sin -> \sin
Dec
9
suggested approved edit on Does the curvature determine the metric?
Nov
16
comment How to find $x$ such that $\tan5x=\tan x$ and $\sin5x=\sin x$?
You are welcome :)
Nov
16
revised How to find $x$ such that $\tan5x=\tan x$ and $\sin5x=\sin x$?
sin to \sin, x to $x$
Nov
16
suggested approved edit on How to find $x$ such that $\tan5x=\tan x$ and $\sin5x=\sin x$?
Nov
16
revised How can I solve this infinite sum?
deleted 2 characters in body
Nov
15
answered When will $AB=BA$?
Sep
24
awarded  Autobiographer
Aug
12
comment What is the oldest open problem in geometry?
I would like to see an animation for a periodic orbit in an obtuse triangle.
Jul
24
revised Probability with Uniform Distribution with Multiple Variables
texified the body
Jul
24
suggested approved edit on Probability with Uniform Distribution with Multiple Variables
Jul
11
comment Limit of the integral: $\int_0^{\pi/2}\beta^\alpha\exp\left(-\beta\cos(\theta)\right)d\theta$
Shouldn't it be $\lim_{\beta\to+\infty}J_0(\beta)=0$? Illustration.
Jul
4
comment 'Obvious' theorems that are actually false
You may be interested in these books: Counterexamples in Analysis, Counterexamples in Topology, and Counterexamples in Probability.
Jul
2
comment How to prove that: $\tan(3\pi/11) + 4\sin(2\pi/11) = \sqrt{11}$
How did you reach the $\sum_i \omega^{2i}=0$?