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Mirrors > Home > MPE Home > Th. List > sb6fALT | Structured version Visualization version GIF version |
Description: Alternate version of sb6f 2537. (Contributed by NM, 2-Jun-1993.) (Revised by Mario Carneiro, 4-Oct-2016.) (Proof modification is discouraged.) (New usage is discouraged.) |
Ref | Expression |
---|---|
dfsb1.p5 | ⊢ (𝜃 ↔ ((𝑥 = 𝑦 → 𝜑) ∧ ∃𝑥(𝑥 = 𝑦 ∧ 𝜑))) |
sb6fALT.1 | ⊢ Ⅎ𝑦𝜑 |
Ref | Expression |
---|---|
sb6fALT | ⊢ (𝜃 ↔ ∀𝑥(𝑥 = 𝑦 → 𝜑)) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | dfsb1.p5 | . . . 4 ⊢ (𝜃 ↔ ((𝑥 = 𝑦 → 𝜑) ∧ ∃𝑥(𝑥 = 𝑦 ∧ 𝜑))) | |
2 | biid 263 | . . . 4 ⊢ (((𝑥 = 𝑦 → ∀𝑦𝜑) ∧ ∃𝑥(𝑥 = 𝑦 ∧ ∀𝑦𝜑)) ↔ ((𝑥 = 𝑦 → ∀𝑦𝜑) ∧ ∃𝑥(𝑥 = 𝑦 ∧ ∀𝑦𝜑))) | |
3 | sb6fALT.1 | . . . . 5 ⊢ Ⅎ𝑦𝜑 | |
4 | 3 | nf5ri 2195 | . . . 4 ⊢ (𝜑 → ∀𝑦𝜑) |
5 | 1, 2, 4 | sbimiALT 2577 | . . 3 ⊢ (𝜃 → ((𝑥 = 𝑦 → ∀𝑦𝜑) ∧ ∃𝑥(𝑥 = 𝑦 ∧ ∀𝑦𝜑))) |
6 | 2 | sb4aALT 2598 | . . 3 ⊢ (((𝑥 = 𝑦 → ∀𝑦𝜑) ∧ ∃𝑥(𝑥 = 𝑦 ∧ ∀𝑦𝜑)) → ∀𝑥(𝑥 = 𝑦 → 𝜑)) |
7 | 5, 6 | syl 17 | . 2 ⊢ (𝜃 → ∀𝑥(𝑥 = 𝑦 → 𝜑)) |
8 | 1 | sb2ALT 2587 | . 2 ⊢ (∀𝑥(𝑥 = 𝑦 → 𝜑) → 𝜃) |
9 | 7, 8 | impbii 211 | 1 ⊢ (𝜃 ↔ ∀𝑥(𝑥 = 𝑦 → 𝜑)) |
Colors of variables: wff setvar class |
Syntax hints: → wi 4 ↔ wb 208 ∧ wa 398 ∀wal 1535 ∃wex 1780 Ⅎwnf 1784 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1796 ax-4 1810 ax-5 1911 ax-6 1970 ax-7 2015 ax-10 2145 ax-12 2177 ax-13 2390 |
This theorem depends on definitions: df-bi 209 df-an 399 df-or 844 df-ex 1781 df-nf 1785 |
This theorem is referenced by: sb5fALT 2603 |
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