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Mirrors > Home > MPE Home > Th. List > eleq2dOLD | Structured version Visualization version GIF version |
Description: Obsolete proof of eleq2d 2673 as of 16-Nov-2020. (Contributed by NM, 27-Dec-1993.) Reduce dependencies on axioms. (Revised by Wolf Lammen, 5-Dec-2019.) (Proof modification is discouraged.) (New usage is discouraged.) |
Ref | Expression |
---|---|
eleq1d.1 | ⊢ (𝜑 → 𝐴 = 𝐵) |
Ref | Expression |
---|---|
eleq2dOLD | ⊢ (𝜑 → (𝐶 ∈ 𝐴 ↔ 𝐶 ∈ 𝐵)) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | eleq1d.1 | . . . 4 ⊢ (𝜑 → 𝐴 = 𝐵) | |
2 | dfcleq 2604 | . . . 4 ⊢ (𝐴 = 𝐵 ↔ ∀𝑥(𝑥 ∈ 𝐴 ↔ 𝑥 ∈ 𝐵)) | |
3 | 1, 2 | sylib 207 | . . 3 ⊢ (𝜑 → ∀𝑥(𝑥 ∈ 𝐴 ↔ 𝑥 ∈ 𝐵)) |
4 | biimp 204 | . . . . . 6 ⊢ ((𝑥 ∈ 𝐴 ↔ 𝑥 ∈ 𝐵) → (𝑥 ∈ 𝐴 → 𝑥 ∈ 𝐵)) | |
5 | 4 | anim2d 587 | . . . . 5 ⊢ ((𝑥 ∈ 𝐴 ↔ 𝑥 ∈ 𝐵) → ((𝑥 = 𝐶 ∧ 𝑥 ∈ 𝐴) → (𝑥 = 𝐶 ∧ 𝑥 ∈ 𝐵))) |
6 | 5 | aleximi 1749 | . . . 4 ⊢ (∀𝑥(𝑥 ∈ 𝐴 ↔ 𝑥 ∈ 𝐵) → (∃𝑥(𝑥 = 𝐶 ∧ 𝑥 ∈ 𝐴) → ∃𝑥(𝑥 = 𝐶 ∧ 𝑥 ∈ 𝐵))) |
7 | biimpr 209 | . . . . . 6 ⊢ ((𝑥 ∈ 𝐴 ↔ 𝑥 ∈ 𝐵) → (𝑥 ∈ 𝐵 → 𝑥 ∈ 𝐴)) | |
8 | 7 | anim2d 587 | . . . . 5 ⊢ ((𝑥 ∈ 𝐴 ↔ 𝑥 ∈ 𝐵) → ((𝑥 = 𝐶 ∧ 𝑥 ∈ 𝐵) → (𝑥 = 𝐶 ∧ 𝑥 ∈ 𝐴))) |
9 | 8 | aleximi 1749 | . . . 4 ⊢ (∀𝑥(𝑥 ∈ 𝐴 ↔ 𝑥 ∈ 𝐵) → (∃𝑥(𝑥 = 𝐶 ∧ 𝑥 ∈ 𝐵) → ∃𝑥(𝑥 = 𝐶 ∧ 𝑥 ∈ 𝐴))) |
10 | 6, 9 | impbid 201 | . . 3 ⊢ (∀𝑥(𝑥 ∈ 𝐴 ↔ 𝑥 ∈ 𝐵) → (∃𝑥(𝑥 = 𝐶 ∧ 𝑥 ∈ 𝐴) ↔ ∃𝑥(𝑥 = 𝐶 ∧ 𝑥 ∈ 𝐵))) |
11 | 3, 10 | syl 17 | . 2 ⊢ (𝜑 → (∃𝑥(𝑥 = 𝐶 ∧ 𝑥 ∈ 𝐴) ↔ ∃𝑥(𝑥 = 𝐶 ∧ 𝑥 ∈ 𝐵))) |
12 | df-clel 2606 | . 2 ⊢ (𝐶 ∈ 𝐴 ↔ ∃𝑥(𝑥 = 𝐶 ∧ 𝑥 ∈ 𝐴)) | |
13 | df-clel 2606 | . 2 ⊢ (𝐶 ∈ 𝐵 ↔ ∃𝑥(𝑥 = 𝐶 ∧ 𝑥 ∈ 𝐵)) | |
14 | 11, 12, 13 | 3bitr4g 302 | 1 ⊢ (𝜑 → (𝐶 ∈ 𝐴 ↔ 𝐶 ∈ 𝐵)) |
Colors of variables: wff setvar class |
Syntax hints: → wi 4 ↔ wb 195 ∧ wa 383 ∀wal 1473 = wceq 1475 ∃wex 1695 ∈ wcel 1977 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1713 ax-4 1728 ax-ext 2590 |
This theorem depends on definitions: df-bi 196 df-an 385 df-ex 1696 df-cleq 2603 df-clel 2606 |
This theorem is referenced by: (None) |
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