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Mirrors > Home > ILE Home > Th. List > nfan | Unicode version |
Description: If is not free in and , it is not free in . (Contributed by Mario Carneiro, 11-Aug-2016.) (Proof shortened by Wolf Lammen, 13-Jan-2018.) |
Ref | Expression |
---|---|
nfan.1 | |
nfan.2 |
Ref | Expression |
---|---|
nfan |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | nfan.1 | . 2 | |
2 | nfan.2 | . . 3 | |
3 | 2 | a1i 9 | . 2 |
4 | 1, 3 | nfan1 1557 | 1 |
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