User Martin

40 votes

Accepted

When exactly is the dual of $L^1$ isomorphic to $L^\infty$ via the natural map?

answered May 29, 2013 at 9:57

31 votes

Accepted

On the norm of a quotient of a Banach space.

answered Feb 11, 2013 at 1:35

19 votes

Accepted

What is the topological dual of a dual space with the weak* topology?

answered Feb 6, 2013 at 21:07

19 votes

On the completeness of the generalized Laguerre polynomials

answered Jun 11, 2013 at 21:00

18 votes

Space of bounded functions is reflexive if the domain is finite

answered Dec 4, 2012 at 6:30

17 votes

Accepted

Approximating indicator function on open set continuous functions

answered Feb 4, 2013 at 21:14

17 votes

Accepted

Closed unbounded operator with domain not closed

answered Mar 28, 2013 at 14:34

15 votes

Let the function $f:[a,b] \to \mathbb R$ be Lipschitz. Show that $f$ maps a set of measure zero onto a set of measure zero

answered Mar 24, 2013 at 10:57

12 votes

Accepted

Space of homeomorphisms Homeo$(S^1)$ of $S^1$ deformation retracts onto $O(2)$

answered Mar 7, 2013 at 5:41

12 votes

Accepted

If weak topology and weak* topology on $X^*$ agree, must $X$ be reflexive?

answered Feb 4, 2013 at 9:55

12 votes

Accepted

Universally measurable sets of $\mathbb{R}^2$

answered Nov 30, 2012 at 18:40

12 votes

Accepted

Composition of Fredholm Operators

answered Jan 31, 2013 at 10:05

12 votes

Accepted

Measurable Cauchy Function is Continuous

answered Apr 14, 2013 at 9:09

12 votes

Accepted

Questions about Rickards proof that $D^b_\mathtt{sg}(A) \equiv \mathtt{stmod}(A)$

answered May 2, 2013 at 8:54

11 votes

Accepted

Regular open set whose boundary has nonzero volume.

answered May 11, 2013 at 18:09

11 votes

Accepted

There are compact operators that are not norm-limits of finite-rank operators

answered Jan 28, 2013 at 15:52

11 votes

Accepted

An explicit construction for a "doubly weak" topology

answered Feb 13, 2013 at 2:47

10 votes

Accepted

The graph of a Borel measurable function $f \colon \mathbb R^{n} \to \mathbb R^{m}$ is a Borel set in $\mathbb{R}^{n+m}$

answered Jan 25, 2013 at 13:14

10 votes

Accepted

Solution of Cauchy functional equation which has an antiderivative

answered May 4, 2013 at 20:49

9 votes

Accepted

Are projections onto closed complemented subspaces of a topological vector space always continuous?

answered Mar 24, 2013 at 21:57

9 votes

Accepted

Do proper dense subgroups of the real numbers have uncountable index

answered Jun 15, 2013 at 18:21

9 votes

Accepted

An operator has closed range if and only if the image of some closed subspace of finite codimension is closed.

answered Nov 14, 2012 at 19:43

9 votes

Accepted

Almost complex structures on spheres

answered Dec 27, 2012 at 10:44

8 votes

Accepted

Free object is a coproduct: $F_{A\cup B}\cong F_A \coprod F_B$

answered Jan 5, 2013 at 23:39

8 votes

Accepted

A commutator identity for bounded linear maps and the identity operator of a non-zero normed space is never a commutator

answered Jan 7, 2013 at 0:28

8 votes

Accepted

Definition of amenable group

answered Feb 24, 2013 at 23:57

8 votes

Accepted

Can C([0,1]) be written as a countable union of compact sets?

answered Feb 2, 2013 at 17:51

8 votes

A bounded sequence in $L^\infty$ has a weak-$^*$ convergent subsequence

answered Jun 19, 2013 at 12:12

7 votes

Accepted

Is Lebesgue measure the only measure that is locally finite, strictly positive and translation-invariant on $\mathbb{R}^n$?

answered Feb 7, 2013 at 4:29

7 votes

Accepted

Is duality an exact functor on Banach spaces or Hilbert spaces?

answered Feb 11, 2013 at 19:55

Stack Exchange Network

114 Answers

When exactly is the dual of $L^1$ isomorphic to $L^\infty$ via the natural map?

On the norm of a quotient of a Banach space.

What is the topological dual of a dual space with the weak* topology?

On the completeness of the generalized Laguerre polynomials

Space of bounded functions is reflexive if the domain is finite

Approximating indicator function on open set continuous functions

Closed unbounded operator with domain not closed

Let the function $f:[a,b] \to \mathbb R$ be Lipschitz. Show that $f$ maps a set of measure zero onto a set of measure zero

Space of homeomorphisms Homeo$(S^1)$ of $S^1$ deformation retracts onto $O(2)$

If weak topology and weak* topology on $X^*$ agree, must $X$ be reflexive?

Universally measurable sets of $\mathbb{R}^2$

Composition of Fredholm Operators

Measurable Cauchy Function is Continuous

Questions about Rickards proof that $D^b_\mathtt{sg}(A) \equiv \mathtt{stmod}(A)$

Regular open set whose boundary has nonzero volume.

There are compact operators that are not norm-limits of finite-rank operators

An explicit construction for a "doubly weak" topology

The graph of a Borel measurable function $f \colon \mathbb R^{n} \to \mathbb R^{m}$ is a Borel set in $\mathbb{R}^{n+m}$

Solution of Cauchy functional equation which has an antiderivative

Are projections onto closed complemented subspaces of a topological vector space always continuous?

Do proper dense subgroups of the real numbers have uncountable index

An operator has closed range if and only if the image of some closed subspace of finite codimension is closed.

Almost complex structures on spheres

Free object is a coproduct: $F_{A\cup B}\cong F_A \coprod F_B$

A commutator identity for bounded linear maps and the identity operator of a non-zero normed space is never a commutator

Definition of amenable group

Can C([0,1]) be written as a countable union of compact sets?

A bounded sequence in $L^\infty$ has a weak-$^*$ convergent subsequence

Is Lebesgue measure the only measure that is locally finite, strictly positive and translation-invariant on $\mathbb{R}^n$?

Is duality an exact functor on Banach spaces or Hilbert spaces?