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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 1495 | . . . 4 ⊢ (∃𝑥𝜑 → ∀𝑥∃𝑥𝜑) | |
3 | 2 | 19.23h 1498 | . . 3 ⊢ (∀𝑥(𝜑 → ∃𝑥𝜑) ↔ (∃𝑥𝜑 → ∃𝑥𝜑)) |
4 | 1, 3 | mpbir 146 | . 2 ⊢ ∀𝑥(𝜑 → ∃𝑥𝜑) |
5 | 4 | spi 1536 | 1 ⊢ (𝜑 → ∃𝑥𝜑) |
Colors of variables: wff set class |
Syntax hints: → wi 4 ∀wal 1351 ∃wex 1492 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-ia1 106 ax-ia2 107 ax-ia3 108 ax-gen 1449 ax-ie1 1493 ax-ie2 1494 ax-4 1510 |
This theorem depends on definitions: df-bi 117 |
This theorem is referenced by: 19.8ad 1591 19.23bi 1592 exim 1599 19.43 1628 hbex 1636 19.2 1638 19.9t 1642 19.9h 1643 excomim 1663 19.38 1676 nexr 1692 sbequ1 1768 equs5e 1795 exdistrfor 1800 sbcof2 1810 mo2n 2054 euor2 2084 2moex 2112 2euex 2113 2moswapdc 2116 2exeu 2118 rspe 2526 rsp2e 2528 ceqex 2866 vn0m 3436 intab 3875 copsexg 4246 eusv2nf 4458 dmcosseq 4900 dminss 5045 imainss 5046 relssdmrn 5151 oprabid 5909 tfrlemibxssdm 6330 tfr1onlembxssdm 6346 tfrcllembxssdm 6359 snexxph 6951 nqprl 7552 nqpru 7553 ltsopr 7597 ltexprlemm 7601 recexprlemopl 7626 recexprlemopu 7628 suplocexprlemrl 7718 |
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