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Mirrors > Home > MPE Home > Th. List > Mathboxes > bj-2exbi | Structured version Visualization version GIF version |
Description: Closed form of 2exbii 1893. (Contributed by BJ, 6-May-2019.) |
Ref | Expression |
---|---|
bj-2exbi | ⊢ (∀𝑥∀𝑦(𝜑 ↔ 𝜓) → (∃𝑥∃𝑦𝜑 ↔ ∃𝑥∃𝑦𝜓)) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | exbi 1891 | . . 3 ⊢ (∀𝑦(𝜑 ↔ 𝜓) → (∃𝑦𝜑 ↔ ∃𝑦𝜓)) | |
2 | 1 | alimi 1855 | . 2 ⊢ (∀𝑥∀𝑦(𝜑 ↔ 𝜓) → ∀𝑥(∃𝑦𝜑 ↔ ∃𝑦𝜓)) |
3 | exbi 1891 | . 2 ⊢ (∀𝑥(∃𝑦𝜑 ↔ ∃𝑦𝜓) → (∃𝑥∃𝑦𝜑 ↔ ∃𝑥∃𝑦𝜓)) | |
4 | 2, 3 | syl 17 | 1 ⊢ (∀𝑥∀𝑦(𝜑 ↔ 𝜓) → (∃𝑥∃𝑦𝜑 ↔ ∃𝑥∃𝑦𝜓)) |
Colors of variables: wff setvar class |
Syntax hints: → wi 4 ↔ wb 198 ∀wal 1599 ∃wex 1823 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1839 ax-4 1853 |
This theorem depends on definitions: df-bi 199 df-ex 1824 |
This theorem is referenced by: bj-3exbi 33179 |
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