Description: The abstraction variables in an operation class abstraction are not free. (Contributed by NM, 25-Apr-1995) (Revised by David Abernethy, 19-Jun-2012)
Ref | Expression | ||
---|---|---|---|
Assertion | nfoprab1 | ⊢ Ⅎ 𝑥 { ⟨ ⟨ 𝑥 , 𝑦 ⟩ , 𝑧 ⟩ ∣ 𝜑 } |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | df-oprab | ⊢ { ⟨ ⟨ 𝑥 , 𝑦 ⟩ , 𝑧 ⟩ ∣ 𝜑 } = { 𝑤 ∣ ∃ 𝑥 ∃ 𝑦 ∃ 𝑧 ( 𝑤 = ⟨ ⟨ 𝑥 , 𝑦 ⟩ , 𝑧 ⟩ ∧ 𝜑 ) } | |
2 | nfe1 | ⊢ Ⅎ 𝑥 ∃ 𝑥 ∃ 𝑦 ∃ 𝑧 ( 𝑤 = ⟨ ⟨ 𝑥 , 𝑦 ⟩ , 𝑧 ⟩ ∧ 𝜑 ) | |
3 | 2 | nfab | ⊢ Ⅎ 𝑥 { 𝑤 ∣ ∃ 𝑥 ∃ 𝑦 ∃ 𝑧 ( 𝑤 = ⟨ ⟨ 𝑥 , 𝑦 ⟩ , 𝑧 ⟩ ∧ 𝜑 ) } |
4 | 1 3 | nfcxfr | ⊢ Ⅎ 𝑥 { ⟨ ⟨ 𝑥 , 𝑦 ⟩ , 𝑧 ⟩ ∣ 𝜑 } |