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Mirrors > Home > MPE Home > Th. List > r2exf | Structured version Visualization version GIF version |
Description: Double restricted existential quantification. (Contributed by Mario Carneiro, 14-Oct-2016.) Use r2exlem 3231. (Revised by Wolf Lammen, 10-Jan-2020.) |
Ref | Expression |
---|---|
r2exf.1 | ⊢ Ⅎ𝑦𝐴 |
Ref | Expression |
---|---|
r2exf | ⊢ (∃𝑥 ∈ 𝐴 ∃𝑦 ∈ 𝐵 𝜑 ↔ ∃𝑥∃𝑦((𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐵) ∧ 𝜑)) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | r2exf.1 | . . 3 ⊢ Ⅎ𝑦𝐴 | |
2 | 1 | r2alf 3147 | . 2 ⊢ (∀𝑥 ∈ 𝐴 ∀𝑦 ∈ 𝐵 ¬ 𝜑 ↔ ∀𝑥∀𝑦((𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐵) → ¬ 𝜑)) |
3 | 2 | r2exlem 3231 | 1 ⊢ (∃𝑥 ∈ 𝐴 ∃𝑦 ∈ 𝐵 𝜑 ↔ ∃𝑥∃𝑦((𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐵) ∧ 𝜑)) |
Colors of variables: wff setvar class |
Syntax hints: ¬ wn 3 ↔ wb 205 ∧ wa 396 ∃wex 1782 ∈ wcel 2106 Ⅎwnfc 2887 ∃wrex 3065 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1798 ax-4 1812 ax-5 1913 ax-6 1971 ax-7 2011 ax-8 2108 ax-12 2171 |
This theorem depends on definitions: df-bi 206 df-an 397 df-ex 1783 df-nf 1787 df-clel 2816 df-nfc 2889 df-ral 3069 df-rex 3070 |
This theorem is referenced by: rexcomf 3284 |
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