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Mirrors > Home > ILE Home > Th. List > nfsbt | GIF version |
Description: Closed form of nfsb 1939. (Contributed by Jim Kingdon, 9-May-2018.) |
Ref | Expression |
---|---|
nfsbt | ⊢ (∀𝑥Ⅎ𝑧𝜑 → Ⅎ𝑧[𝑦 / 𝑥]𝜑) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | ax-17 1519 | . 2 ⊢ (∀𝑥Ⅎ𝑧𝜑 → ∀𝑤∀𝑥Ⅎ𝑧𝜑) | |
2 | nfsbxyt 1936 | . . . . 5 ⊢ (∀𝑥Ⅎ𝑧𝜑 → Ⅎ𝑧[𝑤 / 𝑥]𝜑) | |
3 | 2 | alimi 1448 | . . . 4 ⊢ (∀𝑤∀𝑥Ⅎ𝑧𝜑 → ∀𝑤Ⅎ𝑧[𝑤 / 𝑥]𝜑) |
4 | nfsbxyt 1936 | . . . 4 ⊢ (∀𝑤Ⅎ𝑧[𝑤 / 𝑥]𝜑 → Ⅎ𝑧[𝑦 / 𝑤][𝑤 / 𝑥]𝜑) | |
5 | 3, 4 | syl 14 | . . 3 ⊢ (∀𝑤∀𝑥Ⅎ𝑧𝜑 → Ⅎ𝑧[𝑦 / 𝑤][𝑤 / 𝑥]𝜑) |
6 | nfv 1521 | . . . . 5 ⊢ Ⅎ𝑤𝜑 | |
7 | 6 | sbco2 1958 | . . . 4 ⊢ ([𝑦 / 𝑤][𝑤 / 𝑥]𝜑 ↔ [𝑦 / 𝑥]𝜑) |
8 | 7 | nfbii 1466 | . . 3 ⊢ (Ⅎ𝑧[𝑦 / 𝑤][𝑤 / 𝑥]𝜑 ↔ Ⅎ𝑧[𝑦 / 𝑥]𝜑) |
9 | 5, 8 | sylib 121 | . 2 ⊢ (∀𝑤∀𝑥Ⅎ𝑧𝜑 → Ⅎ𝑧[𝑦 / 𝑥]𝜑) |
10 | 1, 9 | syl 14 | 1 ⊢ (∀𝑥Ⅎ𝑧𝜑 → Ⅎ𝑧[𝑦 / 𝑥]𝜑) |
Colors of variables: wff set class |
Syntax hints: → wi 4 ∀wal 1346 Ⅎwnf 1453 [wsb 1755 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-ia1 105 ax-ia2 106 ax-ia3 107 ax-io 704 ax-5 1440 ax-7 1441 ax-gen 1442 ax-ie1 1486 ax-ie2 1487 ax-8 1497 ax-10 1498 ax-11 1499 ax-i12 1500 ax-bndl 1502 ax-4 1503 ax-17 1519 ax-i9 1523 ax-ial 1527 ax-i5r 1528 |
This theorem depends on definitions: df-bi 116 df-nf 1454 df-sb 1756 |
This theorem is referenced by: nfsbd 1970 setindft 14000 |
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