On a question concerning sharp bases
A sharp base B is a base such that whenever ( B i ) i < ω is an injective sequence from B with x ∈ ⋂ i < ω B i , then { ⋂ i < n B i : n < ω } is a base at x. Alleche, Arhangel'skiĭ and Calbrix asked: if X has a sharp base, must X × [ 0 , 1 ] have a sharp base? Good, Knight and Moham...
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Published in | Topology and its applications Vol. 153; no. 1; pp. 90 - 96 |
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Main Authors | , |
Format | Journal Article |
Language | English |
Published |
Elsevier B.V
01.08.2005
|
Subjects | |
Online Access | Get full text |
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Summary: | A sharp base
B
is a base such that whenever
(
B
i
)
i
<
ω
is an injective sequence from
B
with
x
∈
⋂
i
<
ω
B
i
, then
{
⋂
i
<
n
B
i
:
n
<
ω
}
is a base at
x. Alleche, Arhangel'skiĭ and Calbrix asked: if
X has a sharp base, must
X
×
[
0
,
1
]
have a sharp base? Good, Knight and Mohamad claimed to construct an example of a Tychonoff space
P with a sharp base such that
P
×
[
0
,
1
]
does not have a sharp base. However, the space was not regular. We show how to modify the construction to make
P Tychonoff. |
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ISSN: | 0166-8641 1879-3207 |
DOI: | 10.1016/j.topol.2004.02.021 |