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Aweygan
  • Member for 7 years, 2 months
  • Last seen this week
  • United States
18 votes

How can I answer this Putnam question more rigorously?

15 votes

Do integrable functions vanish at infinity?

13 votes
Accepted

If $H$ and $K$ are normal subgroups of $G$ and $H \cong K$, prove that $G/H \cong G/K$.

12 votes
Accepted

Does each compact operator have a non–zero eigenvector?

11 votes
Accepted

Which sets are "clompact"?

9 votes

A vector space is finite dimensional if all of its proper subspaces are finite dimensional

8 votes
Accepted

If $E$ is Banach and $E^*$ is its dual, is every $T:E^*\rightarrow E^*$ an adjoint?

8 votes
Accepted

Extending the spectral theorem for bounded self adjoint operators to bounded normal operators

8 votes
Accepted

If $A$ is a real or complex algebra and $a\in A$ is such that $ab=0$ for all $b\in A$, then $a=0$?

8 votes

On notation: is it better to say $A^B = \{f| f:B \to A\}$ or $A^B = \{f :B \to A| f \text{ is a function}\}$

7 votes

Does $\int_{-x}^{x}f(t)dt=0$ implies $f$ to be an odd function?

7 votes

What is a countably generated $\sigma$-algebra? Can't find a definition online

7 votes
Accepted

Check or falsify: there is a $C^\infty$ surjective map $S^1 \to S^1 \times S^1$.

7 votes

The norm of the difference of two projections in a C$^\ast$-algebra

7 votes

Reason for $(0,1)$ tensor as a vector?

7 votes
Accepted

Why is an operator composed with its adjoint positive and stricly positive when it's invertible?

7 votes
Accepted

Set of Polynomials divided by single linear factor is linearly independent

6 votes
Accepted

Problems with the definition of an adjunction space

6 votes
Accepted

Triangle inequality for Minkowski functional

6 votes
Accepted

Fenchel conjugate of a norm

6 votes

How to prove that if $f:\mathbb{R} \to \mathbb{R}^2$ is of class $C^1$, then $f$ is not onto.

6 votes
Accepted

An example of a non unitary isometry on $L^2(\mathbb{R})$?

6 votes
Accepted

A weakly convergent sequence in a compact set, is strongly convegnet

6 votes
Accepted

dense *-subalgebra that is not an ideal

6 votes
Accepted

In a ring $a \cdot a=a$ then $a+a=0$

6 votes
Accepted

Are all finite dimensional algebras over the real numbers `Banach algebra'-able

6 votes
Accepted

Prove the dual space of $l^p$ is isomorphic to $l^q$ if $\frac{1}{q}+\frac{1}{p}=1$

5 votes

Is the diagonal of $X \times X$ closed in $\bar{X} \times \bar{X}$?

5 votes
Accepted

Why the weak topology is never metrizable?

5 votes

Spectrum of unitary operators lie in the unit circle

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