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| Mirrors > Home > ILE Home > Th. List > abbidv | GIF version | ||
| Description: Equivalent wff's yield equal class abstractions (deduction form). (Contributed by NM, 10-Aug-1993.) | 
| Ref | Expression | 
|---|---|
| abbidv.1 | ⊢ (𝜑 → (𝜓 ↔ 𝜒)) | 
| Ref | Expression | 
|---|---|
| abbidv | ⊢ (𝜑 → {𝑥 ∣ 𝜓} = {𝑥 ∣ 𝜒}) | 
| Step | Hyp | Ref | Expression | 
|---|---|---|---|
| 1 | nfv 1542 | . 2 ⊢ Ⅎ𝑥𝜑 | |
| 2 | abbidv.1 | . 2 ⊢ (𝜑 → (𝜓 ↔ 𝜒)) | |
| 3 | 1, 2 | abbid 2313 | 1 ⊢ (𝜑 → {𝑥 ∣ 𝜓} = {𝑥 ∣ 𝜒}) | 
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