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Mirrors > Home > MPE Home > Th. List > rspc2ev | Structured version Visualization version GIF version |
Description: 2-variable restricted existential specialization, using implicit substitution. (Contributed by NM, 16-Oct-1999.) |
Ref | Expression |
---|---|
rspc2v.1 | ⊢ (𝑥 = 𝐴 → (𝜑 ↔ 𝜒)) |
rspc2v.2 | ⊢ (𝑦 = 𝐵 → (𝜒 ↔ 𝜓)) |
Ref | Expression |
---|---|
rspc2ev | ⊢ ((𝐴 ∈ 𝐶 ∧ 𝐵 ∈ 𝐷 ∧ 𝜓) → ∃𝑥 ∈ 𝐶 ∃𝑦 ∈ 𝐷 𝜑) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | rspc2v.2 | . . . . 5 ⊢ (𝑦 = 𝐵 → (𝜒 ↔ 𝜓)) | |
2 | 1 | rspcev 3607 | . . . 4 ⊢ ((𝐵 ∈ 𝐷 ∧ 𝜓) → ∃𝑦 ∈ 𝐷 𝜒) |
3 | 2 | anim2i 616 | . . 3 ⊢ ((𝐴 ∈ 𝐶 ∧ (𝐵 ∈ 𝐷 ∧ 𝜓)) → (𝐴 ∈ 𝐶 ∧ ∃𝑦 ∈ 𝐷 𝜒)) |
4 | 3 | 3impb 1113 | . 2 ⊢ ((𝐴 ∈ 𝐶 ∧ 𝐵 ∈ 𝐷 ∧ 𝜓) → (𝐴 ∈ 𝐶 ∧ ∃𝑦 ∈ 𝐷 𝜒)) |
5 | rspc2v.1 | . . . 4 ⊢ (𝑥 = 𝐴 → (𝜑 ↔ 𝜒)) | |
6 | 5 | rexbidv 3173 | . . 3 ⊢ (𝑥 = 𝐴 → (∃𝑦 ∈ 𝐷 𝜑 ↔ ∃𝑦 ∈ 𝐷 𝜒)) |
7 | 6 | rspcev 3607 | . 2 ⊢ ((𝐴 ∈ 𝐶 ∧ ∃𝑦 ∈ 𝐷 𝜒) → ∃𝑥 ∈ 𝐶 ∃𝑦 ∈ 𝐷 𝜑) |
8 | 4, 7 | syl 17 | 1 ⊢ ((𝐴 ∈ 𝐶 ∧ 𝐵 ∈ 𝐷 ∧ 𝜓) → ∃𝑥 ∈ 𝐶 ∃𝑦 ∈ 𝐷 𝜑) |
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