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| Mirrors > Home > ILE Home > Th. List > cbvrexv | GIF version | ||
| Description: Change the bound variable of a restricted existential quantifier using implicit substitution. (Contributed by NM, 2-Jun-1998.) |
| Ref | Expression |
|---|---|
| cbvralv.1 | ⊢ (𝑥 = 𝑦 → (𝜑 ↔ 𝜓)) |
| Ref | Expression |
|---|---|
| cbvrexv | ⊢ (∃𝑥 ∈ 𝐴 𝜑 ↔ ∃𝑦 ∈ 𝐴 𝜓) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | nfv 1542 | . 2 ⊢ Ⅎ𝑦𝜑 | |
| 2 | nfv 1542 | . 2 ⊢ Ⅎ𝑥𝜓 | |
| 3 | cbvralv.1 | . 2 ⊢ (𝑥 = 𝑦 → (𝜑 ↔ 𝜓)) | |
| 4 | 1, 2, 3 | cbvrex 2726 | 1 ⊢ (∃𝑥 ∈ 𝐴 𝜑 ↔ ∃𝑦 ∈ 𝐴 𝜓) |
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