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| Mirrors > Home > MPE Home > Th. List > elab | Structured version Visualization version GIF version | ||
| Description: Membership in a class abstraction, using implicit substitution. Compare Theorem 6.13 of [Quine] p. 44. (Contributed by NM, 1-Aug-1994.) |
| Ref | Expression |
|---|---|
| elab.1 | ⊢ 𝐴 ∈ V |
| elab.2 | ⊢ (𝑥 = 𝐴 → (𝜑 ↔ 𝜓)) |
| Ref | Expression |
|---|---|
| elab | ⊢ (𝐴 ∈ {𝑥 ∣ 𝜑} ↔ 𝜓) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | nfv 1843 | . 2 ⊢ Ⅎ𝑥𝜓 | |
| 2 | elab.1 | . 2 ⊢ 𝐴 ∈ V | |
| 3 | elab.2 | . 2 ⊢ (𝑥 = 𝐴 → (𝜑 ↔ 𝜓)) | |
| 4 | 1, 2, 3 | elabf 3349 | 1 ⊢ (𝐴 ∈ {𝑥 ∣ 𝜑} ↔ 𝜓) |
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