Metamath Proof Explorer
Description: Bound-variable hypothesis builder for indexed union. (Contributed by NM, 12-Oct-2003) Avoid ax-11 , ax-12 . (Revised by SN, 14-May-2025)
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|
Ref |
Expression |
|
Assertion |
nfiu1 |
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Proof
Step |
Hyp |
Ref |
Expression |
1 |
|
eliun |
|
2 |
|
nfre1 |
|
3 |
1 2
|
nfxfr |
|
4 |
3
|
nfci |
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