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Description: axrep6 in class notation. It is equivalent to both ax-rep and abrexexg , providing a direct link between the two. (Contributed by SN, 11-Dec-2024)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | axrep6g | ⊢ ( ( 𝐴 ∈ 𝑉 ∧ ∀ 𝑥 ∃* 𝑦 𝜓 ) → { 𝑦 ∣ ∃ 𝑥 ∈ 𝐴 𝜓 } ∈ V ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | rexeq | ⊢ ( 𝑧 = 𝐴 → ( ∃ 𝑥 ∈ 𝑧 𝜓 ↔ ∃ 𝑥 ∈ 𝐴 𝜓 ) ) | |
| 2 | 1 | abbidv | ⊢ ( 𝑧 = 𝐴 → { 𝑦 ∣ ∃ 𝑥 ∈ 𝑧 𝜓 } = { 𝑦 ∣ ∃ 𝑥 ∈ 𝐴 𝜓 } ) |
| 3 | 2 | eleq1d | ⊢ ( 𝑧 = 𝐴 → ( { 𝑦 ∣ ∃ 𝑥 ∈ 𝑧 𝜓 } ∈ V ↔ { 𝑦 ∣ ∃ 𝑥 ∈ 𝐴 𝜓 } ∈ V ) ) |
| 4 | 3 | imbi2d | ⊢ ( 𝑧 = 𝐴 → ( ( ∀ 𝑥 ∃* 𝑦 𝜓 → { 𝑦 ∣ ∃ 𝑥 ∈ 𝑧 𝜓 } ∈ V ) ↔ ( ∀ 𝑥 ∃* 𝑦 𝜓 → { 𝑦 ∣ ∃ 𝑥 ∈ 𝐴 𝜓 } ∈ V ) ) ) |
| 5 | axrep6 | ⊢ ( ∀ 𝑥 ∃* 𝑦 𝜓 → ∃ 𝑤 ∀ 𝑦 ( 𝑦 ∈ 𝑤 ↔ ∃ 𝑥 ∈ 𝑧 𝜓 ) ) | |
| 6 | abbi | ⊢ ( ∀ 𝑦 ( 𝑦 ∈ 𝑤 ↔ ∃ 𝑥 ∈ 𝑧 𝜓 ) → { 𝑦 ∣ 𝑦 ∈ 𝑤 } = { 𝑦 ∣ ∃ 𝑥 ∈ 𝑧 𝜓 } ) | |
| 7 | abid2 | ⊢ { 𝑦 ∣ 𝑦 ∈ 𝑤 } = 𝑤 | |
| 8 | vex | ⊢ 𝑤 ∈ V | |
| 9 | 7 8 | eqeltri | ⊢ { 𝑦 ∣ 𝑦 ∈ 𝑤 } ∈ V |
| 10 | 6 9 | eqeltrrdi | ⊢ ( ∀ 𝑦 ( 𝑦 ∈ 𝑤 ↔ ∃ 𝑥 ∈ 𝑧 𝜓 ) → { 𝑦 ∣ ∃ 𝑥 ∈ 𝑧 𝜓 } ∈ V ) |
| 11 | 10 | exlimiv | ⊢ ( ∃ 𝑤 ∀ 𝑦 ( 𝑦 ∈ 𝑤 ↔ ∃ 𝑥 ∈ 𝑧 𝜓 ) → { 𝑦 ∣ ∃ 𝑥 ∈ 𝑧 𝜓 } ∈ V ) |
| 12 | 5 11 | syl | ⊢ ( ∀ 𝑥 ∃* 𝑦 𝜓 → { 𝑦 ∣ ∃ 𝑥 ∈ 𝑧 𝜓 } ∈ V ) |
| 13 | 4 12 | vtoclg | ⊢ ( 𝐴 ∈ 𝑉 → ( ∀ 𝑥 ∃* 𝑦 𝜓 → { 𝑦 ∣ ∃ 𝑥 ∈ 𝐴 𝜓 } ∈ V ) ) |
| 14 | 13 | imp | ⊢ ( ( 𝐴 ∈ 𝑉 ∧ ∀ 𝑥 ∃* 𝑦 𝜓 ) → { 𝑦 ∣ ∃ 𝑥 ∈ 𝐴 𝜓 } ∈ V ) |