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Mirrors > Home > ILE Home > Th. List > rexalim | GIF version |
Description: Relationship between restricted universal and existential quantifiers. (Contributed by Jim Kingdon, 17-Aug-2018.) |
Ref | Expression |
---|---|
rexalim | ⊢ (∃𝑥 ∈ 𝐴 𝜑 → ¬ ∀𝑥 ∈ 𝐴 ¬ 𝜑) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | ralnex 2458 | . . 3 ⊢ (∀𝑥 ∈ 𝐴 ¬ 𝜑 ↔ ¬ ∃𝑥 ∈ 𝐴 𝜑) | |
2 | 1 | biimpi 119 | . 2 ⊢ (∀𝑥 ∈ 𝐴 ¬ 𝜑 → ¬ ∃𝑥 ∈ 𝐴 𝜑) |
3 | 2 | con2i 622 | 1 ⊢ (∃𝑥 ∈ 𝐴 𝜑 → ¬ ∀𝑥 ∈ 𝐴 ¬ 𝜑) |
Colors of variables: wff set class |
Syntax hints: ¬ wn 3 → wi 4 ∀wral 2448 ∃wrex 2449 |
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-in1 609 ax-in2 610 ax-5 1440 ax-gen 1442 ax-ie2 1487 |
This theorem depends on definitions: df-bi 116 df-tru 1351 df-fal 1354 df-ral 2453 df-rex 2454 |
This theorem is referenced by: infnlbti 7000 |
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