Reputation
34,085
Next tag badge:
386/400 score
138/80 answers
Badges
1 36 96
Newest
 Excavator
Impact
~824k people reached

1h
answered Are there nonsmooth Lie groups?
8h
comment Complex integral $1/(z^2+1)$ along unit circle
In any attempt to use a value for a divergent integral, you should be careful.
8h
comment How to reverse $n\log n$?
possible duplicate of inverse function of $y=ax\ln(bx)$
13h
answered Predual of $l^1(\Gamma)$
13h
comment How to find the limit points of the set $\{\ a+\alpha\ b \mid a,b \in \mathbb Z, \ \alpha\ \text{is a fixed irrational number} \}$
With "$\alpha$ is irrational" inside the brackets, this is very easy. I assume the source of the question does not have that inside the brackets, but has one fixed $\alpha$ in mind. That would be a standard problem.
1d
revised Radon-Nikodem Derivative of a purely nonatomic Borel Measure
added 42 characters in body
1d
answered Radon-Nikodem Derivative of a purely nonatomic Borel Measure
1d
comment Radon-Nikodem Derivative of a purely nonatomic Borel Measure
You also need to say what is the "Lebesgue measure" in your definition when $X$ is not eulidean space.
2d
comment $L^1([0, 1]) \subset C([0, 1])^*$
Even more, the inclusion is isometric: the $L_1$ norm of $g$ equals the operator norm of $\varphi$.
2d
answered $L^1([0, 1]) \subset C([0, 1])^*$
2d
comment Question about homomorphisms
We are given a map $f$ that satisfies $f(x*y)=f(x).f(y)$ ... If $f$ is merely surjective (not injective) and $S$ is a group, we must show that $T$ is also group. For example, we must show that $.$ is associative.
2d
comment Fundamental theorem of calculus for the Lebesgue integral
Did you have some problem understanding the proof in your textbook on measure theory? Wasn't there a question here recently about "what good is the Vitali covering theorem"? Well, maybe that guy should look here!
2d
comment Why do I get a big error when I compute this integral with Gauss-Legendre Quadrature?
The error for Gaussian quadrature is estimated using some derivative of your integrand. If that derivative is unbounded (as in this case), then the error estimate tells you nothing!
2d
comment Find two matrices $A$ and $B$ such that matrix $AB$ that is invertible but $BA$ is not.
For square matrices, use determinants to see that we cannot do it.
2d
comment which functions can be obtained as a composition of a continuous function with itself?
And a plug math.stackexchange.com/a/215096/442 and math.stackexchange.com/a/370651/442
2d
comment which functions can be obtained as a composition of a continuous function with itself?
Also see mathoverflow.net/q/4347/454 and mathoverflow.net/q/17614/454
2d
comment Euler's Equation
@G.Sassatelli: Yes, that one is far more useful and far less mysterious.
2d
comment $A\backslash (B\cap C) = (A\backslash B)\cup (A\backslash C)$; only one inclusion seems to work
Draw a Venn diagram. This may suggest whether this is true, and, if so, what you have to prove.
2d
comment for all $x$, $P(x)$ implies there exists $x$, $P(x)$?
As long as there is a nonempty universe.
May
24
comment What is an adjective for “weaker than weak”?
weaker ... (is that what you want?)