Database
ZF (ZERMELO-FRAENKEL) SET THEORY
ZF Set Theory - start with the Axiom of Extensionality
The universal class
vtocl3gaOLD
Metamath Proof Explorer
Description: Obsolete version of vtocl3ga as of 3-Oct-2024. (Contributed by NM , 20-Aug-1995) (Proof modification is discouraged.)
(New usage is discouraged.)
Ref
Expression
Hypotheses
vtocl3gaOLD.1
⊢ ( 𝑥 = 𝐴 → ( 𝜑 ↔ 𝜓 ) )
vtocl3gaOLD.2
⊢ ( 𝑦 = 𝐵 → ( 𝜓 ↔ 𝜒 ) )
vtocl3gaOLD.3
⊢ ( 𝑧 = 𝐶 → ( 𝜒 ↔ 𝜃 ) )
vtocl3gaOLD.4
⊢ ( ( 𝑥 ∈ 𝐷 ∧ 𝑦 ∈ 𝑅 ∧ 𝑧 ∈ 𝑆 ) → 𝜑 )
Assertion
vtocl3gaOLD
⊢ ( ( 𝐴 ∈ 𝐷 ∧ 𝐵 ∈ 𝑅 ∧ 𝐶 ∈ 𝑆 ) → 𝜃 )
Proof
Step
Hyp
Ref
Expression
1
vtocl3gaOLD.1
⊢ ( 𝑥 = 𝐴 → ( 𝜑 ↔ 𝜓 ) )
2
vtocl3gaOLD.2
⊢ ( 𝑦 = 𝐵 → ( 𝜓 ↔ 𝜒 ) )
3
vtocl3gaOLD.3
⊢ ( 𝑧 = 𝐶 → ( 𝜒 ↔ 𝜃 ) )
4
vtocl3gaOLD.4
⊢ ( ( 𝑥 ∈ 𝐷 ∧ 𝑦 ∈ 𝑅 ∧ 𝑧 ∈ 𝑆 ) → 𝜑 )
5
nfcv
⊢ Ⅎ 𝑥 𝐴
6
nfcv
⊢ Ⅎ 𝑦 𝐴
7
nfcv
⊢ Ⅎ 𝑧 𝐴
8
nfcv
⊢ Ⅎ 𝑦 𝐵
9
nfcv
⊢ Ⅎ 𝑧 𝐵
10
nfcv
⊢ Ⅎ 𝑧 𝐶
11
nfv
⊢ Ⅎ 𝑥 𝜓
12
nfv
⊢ Ⅎ 𝑦 𝜒
13
nfv
⊢ Ⅎ 𝑧 𝜃
14
5 6 7 8 9 10 11 12 13 1 2 3 4
vtocl3gaf
⊢ ( ( 𝐴 ∈ 𝐷 ∧ 𝐵 ∈ 𝑅 ∧ 𝐶 ∈ 𝑆 ) → 𝜃 )