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Mirrors > Home > MPE Home > Th. List > 19.36 | Structured version Visualization version GIF version |
Description: Theorem 19.36 of [Margaris] p. 90. See 19.36v 1991 for a version requiring fewer axioms. (Contributed by NM, 24-Jun-1993.) |
Ref | Expression |
---|---|
19.36.1 | ⊢ Ⅎ𝑥𝜓 |
Ref | Expression |
---|---|
19.36 | ⊢ (∃𝑥(𝜑 → 𝜓) ↔ (∀𝑥𝜑 → 𝜓)) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | 19.35 1880 | . 2 ⊢ (∃𝑥(𝜑 → 𝜓) ↔ (∀𝑥𝜑 → ∃𝑥𝜓)) | |
2 | 19.36.1 | . . . 4 ⊢ Ⅎ𝑥𝜓 | |
3 | 2 | 19.9 2198 | . . 3 ⊢ (∃𝑥𝜓 ↔ 𝜓) |
4 | 3 | imbi2i 336 | . 2 ⊢ ((∀𝑥𝜑 → ∃𝑥𝜓) ↔ (∀𝑥𝜑 → 𝜓)) |
5 | 1, 4 | bitri 274 | 1 ⊢ (∃𝑥(𝜑 → 𝜓) ↔ (∀𝑥𝜑 → 𝜓)) |
Colors of variables: wff setvar class |
Syntax hints: → wi 4 ↔ wb 205 ∀wal 1537 ∃wex 1782 Ⅎwnf 1786 |
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-12 2171 |
This theorem depends on definitions: df-bi 206 df-ex 1783 df-nf 1787 |
This theorem is referenced by: 19.36i 2224 19.12vv 2345 spcimgft 3526 19.12b 33777 |
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