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Mirrors > Home > MPE Home > Th. List > nfrab1 | Structured version Visualization version GIF version |
Description: The abstraction variable in a restricted class abstraction isn't free. (Contributed by NM, 19-Mar-1997.) |
Ref | Expression |
---|---|
nfrab1 | ⊢ Ⅎ𝑥{𝑥 ∈ 𝐴 ∣ 𝜑} |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | df-rab 3074 | . 2 ⊢ {𝑥 ∈ 𝐴 ∣ 𝜑} = {𝑥 ∣ (𝑥 ∈ 𝐴 ∧ 𝜑)} | |
2 | nfab1 2910 | . 2 ⊢ Ⅎ𝑥{𝑥 ∣ (𝑥 ∈ 𝐴 ∧ 𝜑)} | |
3 | 1, 2 | nfcxfr 2906 | 1 ⊢ Ⅎ𝑥{𝑥 ∈ 𝐴 ∣ 𝜑} |
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