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Mirrors > Home > MPE Home > Th. List > ceqsal1t | Structured version Visualization version GIF version |
Description: One direction of ceqsalt 3500 is based on fewer assumptions and fewer axioms. It is at the same time the reverse direction of vtoclgft 3535. Extracted from a proof of ceqsalt 3500. (Contributed by Wolf Lammen, 25-Mar-2025.) |
Ref | Expression |
---|---|
ceqsal1t | ⊢ ((Ⅎ𝑥𝜓 ∧ ∀𝑥(𝑥 = 𝐴 → (𝜑 ↔ 𝜓))) → (𝜓 → ∀𝑥(𝑥 = 𝐴 → 𝜑))) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | biimpr 219 | . . . . . 6 ⊢ ((𝜑 ↔ 𝜓) → (𝜓 → 𝜑)) | |
2 | 1 | imim2i 16 | . . . . 5 ⊢ ((𝑥 = 𝐴 → (𝜑 ↔ 𝜓)) → (𝑥 = 𝐴 → (𝜓 → 𝜑))) |
3 | 2 | com23 86 | . . . 4 ⊢ ((𝑥 = 𝐴 → (𝜑 ↔ 𝜓)) → (𝜓 → (𝑥 = 𝐴 → 𝜑))) |
4 | 3 | alimi 1805 | . . 3 ⊢ (∀𝑥(𝑥 = 𝐴 → (𝜑 ↔ 𝜓)) → ∀𝑥(𝜓 → (𝑥 = 𝐴 → 𝜑))) |
5 | 19.21t 2191 | . . 3 ⊢ (Ⅎ𝑥𝜓 → (∀𝑥(𝜓 → (𝑥 = 𝐴 → 𝜑)) ↔ (𝜓 → ∀𝑥(𝑥 = 𝐴 → 𝜑)))) | |
6 | 4, 5 | imbitrid 243 | . 2 ⊢ (Ⅎ𝑥𝜓 → (∀𝑥(𝑥 = 𝐴 → (𝜑 ↔ 𝜓)) → (𝜓 → ∀𝑥(𝑥 = 𝐴 → 𝜑)))) |
7 | 6 | imp 406 | 1 ⊢ ((Ⅎ𝑥𝜓 ∧ ∀𝑥(𝑥 = 𝐴 → (𝜑 ↔ 𝜓))) → (𝜓 → ∀𝑥(𝑥 = 𝐴 → 𝜑))) |
Colors of variables: wff setvar class |
Syntax hints: → wi 4 ↔ wb 205 ∧ wa 395 ∀wal 1531 = wceq 1533 Ⅎwnf 1777 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1789 ax-4 1803 ax-5 1905 ax-6 1963 ax-7 2003 ax-12 2163 |
This theorem depends on definitions: df-bi 206 df-an 396 df-ex 1774 df-nf 1778 |
This theorem is referenced by: ceqsalt 3500 |
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