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Sum of singleton and Sierpinski space
Let
X
=
{
0
,
1
,
2
}
X = \{0,1,2\}
X
=
{
0
,
1
,
2
}
with open sets
{
∅
,
{
0
}
,
{
1
}
,
{
0
,
1
}
,
{
1
,
2
}
,
{
0
,
1
,
2
}
}
\{\emptyset, \{0\}, \{1\}, \{0,1\}, \{1,2\}, \{0,1,2\} \}
{
∅
,
{
0
}
,
{
1
}
,
{
0
,
1
}
,
{
1
,
2
}
,
{
0
,
1
,
2
}}
, that is, the topological sum of
The Singleton
with pointset
{
0
}
\{0\}
{
0
}
and
Sierpinski Space
with pointset
{
1
,
2
}
\{1,2\}
{
1
,
2
}
.
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