On a problem of Nogura about the product of Fréchet-Urysohn $\langle \alpha _4\rangle $-spaces

Camillo Costantini

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Displaying similar documents to “On a problem of Nogura about the product of Fréchet-Urysohn $〈 α_{4} 〉$ -spaces”

No hedgehog in the product?

Petr Simon, Gino Tironi (2002)

Commentationes Mathematicae Universitatis Carolinae

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Assuming OCA, we shall prove that for some pairs of Fréchet $α_{4}$ -spaces $X, Y$ , the Fréchetness of the product $X \times Y$ implies that $X \times Y$ is $α_{4}$ . Assuming MA, we shall construct a pair of spaces satisfying the assumptions of the theorem.

Fréchet property in compact spaces is not preserved by $M$ -equivalence

Oleg Okunev (2005)

Commentationes Mathematicae Universitatis Carolinae

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An example of two $M$ -equivalent (hence $l$ -equivalent) compact spaces is presented, one of which is Fréchet and the other is not.

A hedgehog in a product

Petr Simon (1998)

Acta Universitatis Carolinae. Mathematica et Physica

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$ω^{ω}$ -directedness and a question of E. Michael

Peg Daniels (1995)

Commentationes Mathematicae Universitatis Carolinae

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We define $ω^{ω}$ -directedness, investigate various properties to determine whether they have this property or not, and use our results to obtain easier proofs of theorems due to Laurence and Alster concerning the existence of a Michael space, i.eȧ Lindelöf space whose product with the irrationals is not Lindelöf.

Displaying similar documents to “On a problem of Nogura about the product of Fréchet-Urysohn 〈 α 4 〉 -spaces”

No hedgehog in the product?

Fréchet property in compact spaces is not preserved by M -equivalence

A hedgehog in a product

ω ω -directedness and a question of E. Michael

Displaying similar documents to “On a problem of Nogura about the product of Fréchet-Urysohn $〈 α_{4} 〉$ -spaces”

Fréchet property in compact spaces is not preserved by $M$ -equivalence

$ω^{ω}$ -directedness and a question of E. Michael