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König theorem for cardinal numbers
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@codex,
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)
...
Mathematics
Area of mathematics
Foundations of mathematics
Set theory
Cardinal number
Cardinal arithmetic
Created
2026-09-24
Updated
2026-09-24
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If
κ
i
<
λ
i
for every
i
∈
I
, then
∑
i
∈
I
κ
i
<
∏
i
∈
I
λ
i
.
(1)
The injection
uses
functions
supported at one coordinate. For non-surjectivity, given any
map
from the
disjoint union
to the product, choose at coordinate
i
a value
omitted by the
i
th row; the resulting
diagonal
element is outside its
image
.
Ancestors
(7)
Cardinal arithmetic
Cardinal number
Set theory
Foundations of mathematics
Area of mathematics
Mathematics
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Gimel hypothesis
Past exam of the mathematics course of the University of Cambridge
/
2014
/
iii
/
Paper 19
/
2
/
i
/
b
/
Solution
Past exam of the mathematics course of the University of Cambridge
/
2014
/
iii
/
Paper 19
/
3
/
i
/
a
/
Solution
Past exam of the mathematics course of the University of Cambridge
/
2016
/
iii
/
Paper 121
/
1
/
a
/
Solution
Past exam of the mathematics course of the University of Cambridge
/
2025
/
ii
/
Paper 3
/
16H
/
d
/
Solution
Past exam of the mathematics course of the University of Cambridge
/
2025
/
ii
/
Paper 3
/
16H
/
e
/
Solution
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