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Mirrors > Home > ILE Home > Th. List > 19.8a | GIF version |
Description: If a wff is true, then it is true for at least one instance. Special case of Theorem 19.8 of [Margaris] p. 89. (Contributed by NM, 5-Aug-1993.) |
Ref | Expression |
---|---|
19.8a | ⊢ (𝜑 → ∃𝑥𝜑) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | id 19 | . . 3 ⊢ (∃𝑥𝜑 → ∃𝑥𝜑) | |
2 | hbe1 1471 | . . . 4 ⊢ (∃𝑥𝜑 → ∀𝑥∃𝑥𝜑) | |
3 | 2 | 19.23h 1474 | . . 3 ⊢ (∀𝑥(𝜑 → ∃𝑥𝜑) ↔ (∃𝑥𝜑 → ∃𝑥𝜑)) |
4 | 1, 3 | mpbir 145 | . 2 ⊢ ∀𝑥(𝜑 → ∃𝑥𝜑) |
5 | 4 | spi 1516 | 1 ⊢ (𝜑 → ∃𝑥𝜑) |
Colors of variables: wff set class |
Syntax hints: → wi 4 ∀wal 1329 ∃wex 1468 |
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-gen 1425 ax-ie1 1469 ax-ie2 1470 ax-4 1487 |
This theorem depends on definitions: df-bi 116 |
This theorem is referenced by: 19.8ad 1570 19.23bi 1571 exim 1578 19.43 1607 hbex 1615 19.2 1617 19.9t 1621 19.9h 1622 excomim 1641 19.38 1654 nexr 1670 sbequ1 1741 equs5e 1767 exdistrfor 1772 sbcof2 1782 mo2n 2025 euor2 2055 2moex 2083 2euex 2084 2moswapdc 2087 2exeu 2089 rspe 2479 rsp2e 2481 ceqex 2807 vn0m 3369 intab 3795 copsexg 4161 eusv2nf 4372 dmcosseq 4805 dminss 4948 imainss 4949 relssdmrn 5054 oprabid 5796 tfrlemibxssdm 6217 tfr1onlembxssdm 6233 tfrcllembxssdm 6246 snexxph 6831 nqprl 7352 nqpru 7353 ltsopr 7397 ltexprlemm 7401 recexprlemopl 7426 recexprlemopu 7428 suplocexprlemrl 7518 |
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