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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 3304. (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 3224 | . 2 ⊢ (∀𝑥 ∈ 𝐴 ∀𝑦 ∈ 𝐵 ¬ 𝜑 ↔ ∀𝑥∀𝑦((𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐵) → ¬ 𝜑)) |
3 | 2 | r2exlem 3304 | 1 ⊢ (∃𝑥 ∈ 𝐴 ∃𝑦 ∈ 𝐵 𝜑 ↔ ∃𝑥∃𝑦((𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐵) ∧ 𝜑)) |
Colors of variables: wff setvar class |
Syntax hints: ¬ wn 3 ↔ wb 208 ∧ wa 398 ∃wex 1780 ∈ wcel 2114 Ⅎwnfc 2963 ∃wrex 3141 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1796 ax-4 1810 ax-5 1911 ax-6 1970 ax-7 2015 ax-8 2116 ax-10 2145 ax-11 2161 ax-12 2177 |
This theorem depends on definitions: df-bi 209 df-an 399 df-ex 1781 df-nf 1785 df-sb 2070 df-clel 2895 df-nfc 2965 df-ral 3145 df-rex 3146 |
This theorem is referenced by: rexcomf 3360 |
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