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Abdelmalek Abdesselam
Abdelmalek Abdesselam
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My first question is the following:

Q1: Let $X$ be a Banach space. If its dual $X^\*$$X^\ast$ is weak* separable, does $X$ admit an infinite-dimensional and separable quotient $X/M$?

To the best of my knowledge, the dual $X^\*$$X^\ast$ is weak* separable, when $X$ satisfies one of the following:

(i) $X$ is separable;

(ii) $X$ is the dual of a separable Banach space;

(iii) $X$ is Hereditary Indecomposable Banach space. That is, every infinite-dimensional closed subspace of $X$ can not be written as a direct sum of two infinite-dimensional closed subspaces.

And, I see that if $X$ satisfies (i) or (ii), $X$ admit an infinite-dimensional and separable quotient.

Q2: Is it true that $X$ admit an infinite-dimensional and separable quotient, if $X$ satisfies (iii) ?

My first question is the following:

Q1: Let $X$ be a Banach space. If its dual $X^\*$ is weak* separable, does $X$ admit an infinite-dimensional and separable quotient $X/M$?

To the best of my knowledge, the dual $X^\*$ is weak* separable, when $X$ satisfies one of the following:

(i) $X$ is separable;

(ii) $X$ is the dual of a separable Banach space;

(iii) $X$ is Hereditary Indecomposable Banach space. That is, every infinite-dimensional closed subspace of $X$ can not be written as a direct sum of two infinite-dimensional closed subspaces.

And, I see that if $X$ satisfies (i) or (ii), $X$ admit an infinite-dimensional and separable quotient.

Q2: Is it true that $X$ admit an infinite-dimensional and separable quotient, if $X$ satisfies (iii) ?

My first question is the following:

Q1: Let $X$ be a Banach space. If its dual $X^\ast$ is weak* separable, does $X$ admit an infinite-dimensional and separable quotient $X/M$?

To the best of my knowledge, the dual $X^\ast$ is weak* separable, when $X$ satisfies one of the following:

(i) $X$ is separable;

(ii) $X$ is the dual of a separable Banach space;

(iii) $X$ is Hereditary Indecomposable Banach space. That is, every infinite-dimensional closed subspace of $X$ can not be written as a direct sum of two infinite-dimensional closed subspaces.

And, I see that if $X$ satisfies (i) or (ii), $X$ admit an infinite-dimensional and separable quotient.

Q2: Is it true that $X$ admit an infinite-dimensional and separable quotient, if $X$ satisfies (iii) ?

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Emil Jeřábek
Emil Jeřábek
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My first question is the following:

Q1: Let $X$ be a Banach space. If its dual $X^*$$X^\*$ is weak* separable, does $X$ admit an infinite-dimensional and separable queotientquotient $X/M$?

To the best of my knowledge, the dual $X^{*}$$X^\*$ is weak* separable, when $X$ satisfies one of the following:

(i) $X$ is separable;

(ii) $X$ is the dual of a separable Banach space;

(iii) $X$ is Hereditary Indecomposable Banach space. That is, every infinite-dimensional closed subspace of $X$ can not be written as a direct sum of two infinite-dimensional closed subspaces.

And, I see that if $X$ satisfies (i) or (ii), $X$ admit an infinite-dimensional and separable queotientquotient.

Q2: Is it true that $X$ admit an infinite-dimensional and separable queotientquotient, if $X$ satisfies (iii) ?

My first question is the following:

Q1: Let $X$ be a Banach space. If its dual $X^*$ is weak* separable, does $X$ admit an infinite-dimensional and separable queotient $X/M$?

To the best of my knowledge, the dual $X^{*}$ is weak* separable, when $X$ satisfies one of the following:

(i) $X$ is separable;

(ii) $X$ is the dual of a separable Banach space;

(iii) $X$ is Hereditary Indecomposable Banach space. That is, every infinite-dimensional closed subspace of $X$ can not be written as a direct sum of two infinite-dimensional closed subspaces.

And, I see that if $X$ satisfies (i) or (ii), $X$ admit an infinite-dimensional and separable queotient.

Q2: Is it true that $X$ admit an infinite-dimensional and separable queotient, if $X$ satisfies (iii) ?

My first question is the following:

Q1: Let $X$ be a Banach space. If its dual $X^\*$ is weak* separable, does $X$ admit an infinite-dimensional and separable quotient $X/M$?

To the best of my knowledge, the dual $X^\*$ is weak* separable, when $X$ satisfies one of the following:

(i) $X$ is separable;

(ii) $X$ is the dual of a separable Banach space;

(iii) $X$ is Hereditary Indecomposable Banach space. That is, every infinite-dimensional closed subspace of $X$ can not be written as a direct sum of two infinite-dimensional closed subspaces.

And, I see that if $X$ satisfies (i) or (ii), $X$ admit an infinite-dimensional and separable quotient.

Q2: Is it true that $X$ admit an infinite-dimensional and separable quotient, if $X$ satisfies (iii) ?

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Qingping Zeng
Qingping Zeng
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Weak star separable and separable quotient problem

My first question is the following:

Q1: Let $X$ be a Banach space. If its dual $X^*$ is weak* separable, does $X$ admit an infinite-dimensional and separable queotient $X/M$?

To the best of my knowledge, the dual $X^{*}$ is weak* separable, when $X$ satisfies one of the following:

(i) $X$ is separable;

(ii) $X$ is the dual of a separable Banach space;

(iii) $X$ is Hereditary Indecomposable Banach space. That is, every infinite-dimensional closed subspace of $X$ can not be written as a direct sum of two infinite-dimensional closed subspaces.

And, I see that if $X$ satisfies (i) or (ii), $X$ admit an infinite-dimensional and separable queotient.

Q2: Is it true that $X$ admit an infinite-dimensional and separable queotient, if $X$ satisfies (iii) ?