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Mirrors > Home > ILE Home > Th. List > ax-ie1 | GIF version |
Description: 𝑥 is bound in ∃𝑥𝜑. One of the axioms of predicate logic. (Contributed by Mario Carneiro, 31-Jan-2015.) |
Ref | Expression |
---|---|
ax-ie1 | ⊢ (∃𝑥𝜑 → ∀𝑥∃𝑥𝜑) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | wph | . . 3 wff 𝜑 | |
2 | vx | . . 3 setvar 𝑥 | |
3 | 1, 2 | wex 1492 | . 2 wff ∃𝑥𝜑 |
4 | 3, 2 | wal 1351 | . 2 wff ∀𝑥∃𝑥𝜑 |
5 | 3, 4 | wi 4 | 1 wff (∃𝑥𝜑 → ∀𝑥∃𝑥𝜑) |
Colors of variables: wff set class |
This axiom is referenced by: hbe1 1495 sbidm 1851 |
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