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Mirrors > Home > ILE Home > Th. List > equs5e | GIF version |
Description: A property related to substitution that unlike equs5 1829 doesn't require a distinctor antecedent. (Contributed by NM, 2-Feb-2007.) (Revised by NM, 3-Feb-2015.) |
Ref | Expression |
---|---|
equs5e | ⊢ (∃𝑥(𝑥 = 𝑦 ∧ 𝜑) → ∀𝑥(𝑥 = 𝑦 → ∃𝑦𝜑)) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | 19.8a 1590 | . . . . 5 ⊢ (𝜑 → ∃𝑦𝜑) | |
2 | hbe1 1495 | . . . . 5 ⊢ (∃𝑦𝜑 → ∀𝑦∃𝑦𝜑) | |
3 | 1, 2 | syl 14 | . . . 4 ⊢ (𝜑 → ∀𝑦∃𝑦𝜑) |
4 | 3 | anim2i 342 | . . 3 ⊢ ((𝑥 = 𝑦 ∧ 𝜑) → (𝑥 = 𝑦 ∧ ∀𝑦∃𝑦𝜑)) |
5 | 4 | eximi 1600 | . 2 ⊢ (∃𝑥(𝑥 = 𝑦 ∧ 𝜑) → ∃𝑥(𝑥 = 𝑦 ∧ ∀𝑦∃𝑦𝜑)) |
6 | equs5a 1794 | . 2 ⊢ (∃𝑥(𝑥 = 𝑦 ∧ ∀𝑦∃𝑦𝜑) → ∀𝑥(𝑥 = 𝑦 → ∃𝑦𝜑)) | |
7 | 5, 6 | syl 14 | 1 ⊢ (∃𝑥(𝑥 = 𝑦 ∧ 𝜑) → ∀𝑥(𝑥 = 𝑦 → ∃𝑦𝜑)) |
Colors of variables: wff set class |
Syntax hints: → wi 4 ∧ wa 104 ∀wal 1351 = wceq 1353 ∃wex 1492 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-ia1 106 ax-ia2 107 ax-ia3 108 ax-5 1447 ax-gen 1449 ax-ie1 1493 ax-ie2 1494 ax-11 1506 ax-4 1510 ax-ial 1534 |
This theorem depends on definitions: df-bi 117 |
This theorem is referenced by: ax11e 1796 sb4e 1805 |
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