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Mirrors > Home > MPE Home > Th. List > nfcxfr | Structured version Visualization version GIF version |
Description: A utility lemma to transfer a bound-variable hypothesis builder into a definition. (Contributed by Mario Carneiro, 11-Aug-2016.) |
Ref | Expression |
---|---|
nfcxfr.1 | ⊢ 𝐴 = 𝐵 |
nfcxfr.2 | ⊢ Ⅎ𝑥𝐵 |
Ref | Expression |
---|---|
nfcxfr | ⊢ Ⅎ𝑥𝐴 |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | nfcxfr.2 | . 2 ⊢ Ⅎ𝑥𝐵 | |
2 | nfcxfr.1 | . . 3 ⊢ 𝐴 = 𝐵 | |
3 | 2 | nfceqi 2903 | . 2 ⊢ (Ⅎ𝑥𝐴 ↔ Ⅎ𝑥𝐵) |
4 | 1, 3 | mpbir 230 | 1 ⊢ Ⅎ𝑥𝐴 |
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