Metamath Proof Explorer
Description: The union of two sets is a set. Corollary 5.8 of TakeutiZaring p. 16.
(Contributed by NM, 1-Jul-1994)
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|
Ref |
Expression |
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Hypotheses |
unex.1 |
|
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|
unex.2 |
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Assertion |
unex |
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Proof
Step |
Hyp |
Ref |
Expression |
1 |
|
unex.1 |
|
2 |
|
unex.2 |
|
3 |
|
unexg |
|
4 |
1 2 3
|
mp2an |
|