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Mirrors > Home > ILE Home > Th. List > r19.2m | GIF version |
Description: Theorem 19.2 of [Margaris] p. 89 with restricted quantifiers (compare 19.2 1572). The restricted version is valid only when the domain of quantification is inhabited. (Contributed by Jim Kingdon, 5-Aug-2018.) |
Ref | Expression |
---|---|
r19.2m | ⊢ ((∃𝑥 𝑥 ∈ 𝐴 ∧ ∀𝑥 ∈ 𝐴 𝜑) → ∃𝑥 ∈ 𝐴 𝜑) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | df-ral 2360 | . . . 4 ⊢ (∀𝑥 ∈ 𝐴 𝜑 ↔ ∀𝑥(𝑥 ∈ 𝐴 → 𝜑)) | |
2 | exintr 1568 | . . . 4 ⊢ (∀𝑥(𝑥 ∈ 𝐴 → 𝜑) → (∃𝑥 𝑥 ∈ 𝐴 → ∃𝑥(𝑥 ∈ 𝐴 ∧ 𝜑))) | |
3 | 1, 2 | sylbi 119 | . . 3 ⊢ (∀𝑥 ∈ 𝐴 𝜑 → (∃𝑥 𝑥 ∈ 𝐴 → ∃𝑥(𝑥 ∈ 𝐴 ∧ 𝜑))) |
4 | df-rex 2361 | . . 3 ⊢ (∃𝑥 ∈ 𝐴 𝜑 ↔ ∃𝑥(𝑥 ∈ 𝐴 ∧ 𝜑)) | |
5 | 3, 4 | syl6ibr 160 | . 2 ⊢ (∀𝑥 ∈ 𝐴 𝜑 → (∃𝑥 𝑥 ∈ 𝐴 → ∃𝑥 ∈ 𝐴 𝜑)) |
6 | 5 | impcom 123 | 1 ⊢ ((∃𝑥 𝑥 ∈ 𝐴 ∧ ∀𝑥 ∈ 𝐴 𝜑) → ∃𝑥 ∈ 𝐴 𝜑) |
Colors of variables: wff set class |
Syntax hints: → wi 4 ∧ wa 102 ∀wal 1285 ∃wex 1424 ∈ wcel 1436 ∀wral 2355 ∃wrex 2356 |
This theorem was proved from axioms: ax-1 5 ax-2 6 ax-mp 7 ax-ia1 104 ax-ia2 105 ax-ia3 106 ax-5 1379 ax-gen 1381 ax-ie1 1425 ax-ie2 1426 ax-4 1443 ax-ial 1470 |
This theorem depends on definitions: df-bi 115 df-ral 2360 df-rex 2361 |
This theorem is referenced by: intssunim 3687 riinm 3779 trintssmOLD 3921 iinexgm 3958 xpiindim 4534 cnviinm 4929 eusvobj2 5580 iinerm 6297 rexfiuz 10263 r19.2uz 10267 climuni 10520 |
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