| Step | Hyp | Ref | Expression | 
|---|
| 1 |  | ensym 9043 | . 2
⊢ ((𝐴 × 𝐴) ≈ (𝐵 ∪ 𝐶) → (𝐵 ∪ 𝐶) ≈ (𝐴 × 𝐴)) | 
| 2 |  | bren 8995 | . . 3
⊢ ((𝐵 ∪ 𝐶) ≈ (𝐴 × 𝐴) ↔ ∃𝑓 𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴)) | 
| 3 |  | ssdif0 4366 | . . . . . 6
⊢ (𝐴 ⊆ (((1st
↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵) ↔ (𝐴 ∖ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵)) = ∅) | 
| 4 |  | dmxpid 5941 | . . . . . . . . . . . . . 14
⊢ dom
(𝐴 × 𝐴) = 𝐴 | 
| 5 |  | f1ofo 6855 | . . . . . . . . . . . . . . . . 17
⊢ (𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) → 𝑓:(𝐵 ∪ 𝐶)–onto→(𝐴 × 𝐴)) | 
| 6 |  | forn 6823 | . . . . . . . . . . . . . . . . 17
⊢ (𝑓:(𝐵 ∪ 𝐶)–onto→(𝐴 × 𝐴) → ran 𝑓 = (𝐴 × 𝐴)) | 
| 7 | 5, 6 | syl 17 | . . . . . . . . . . . . . . . 16
⊢ (𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) → ran 𝑓 = (𝐴 × 𝐴)) | 
| 8 |  | vex 3484 | . . . . . . . . . . . . . . . . 17
⊢ 𝑓 ∈ V | 
| 9 | 8 | rnex 7932 | . . . . . . . . . . . . . . . 16
⊢ ran 𝑓 ∈ V | 
| 10 | 7, 9 | eqeltrrdi 2850 | . . . . . . . . . . . . . . 15
⊢ (𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) → (𝐴 × 𝐴) ∈ V) | 
| 11 | 10 | dmexd 7925 | . . . . . . . . . . . . . 14
⊢ (𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) → dom (𝐴 × 𝐴) ∈ V) | 
| 12 | 4, 11 | eqeltrrid 2846 | . . . . . . . . . . . . 13
⊢ (𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) → 𝐴 ∈ V) | 
| 13 |  | imassrn 6089 | . . . . . . . . . . . . . 14
⊢
(((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵) ⊆ ran ((1st ↾
(𝐴 × 𝐴)) ∘ 𝑓) | 
| 14 |  | f1stres 8038 | . . . . . . . . . . . . . . . 16
⊢
(1st ↾ (𝐴 × 𝐴)):(𝐴 × 𝐴)⟶𝐴 | 
| 15 |  | f1of 6848 | . . . . . . . . . . . . . . . 16
⊢ (𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) → 𝑓:(𝐵 ∪ 𝐶)⟶(𝐴 × 𝐴)) | 
| 16 |  | fco 6760 | . . . . . . . . . . . . . . . 16
⊢
(((1st ↾ (𝐴 × 𝐴)):(𝐴 × 𝐴)⟶𝐴 ∧ 𝑓:(𝐵 ∪ 𝐶)⟶(𝐴 × 𝐴)) → ((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓):(𝐵 ∪ 𝐶)⟶𝐴) | 
| 17 | 14, 15, 16 | sylancr 587 | . . . . . . . . . . . . . . 15
⊢ (𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) → ((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓):(𝐵 ∪ 𝐶)⟶𝐴) | 
| 18 | 17 | frnd 6744 | . . . . . . . . . . . . . 14
⊢ (𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) → ran ((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) ⊆ 𝐴) | 
| 19 | 13, 18 | sstrid 3995 | . . . . . . . . . . . . 13
⊢ (𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) → (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵) ⊆ 𝐴) | 
| 20 | 12, 19 | ssexd 5324 | . . . . . . . . . . . 12
⊢ (𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) → (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵) ∈ V) | 
| 21 | 20 | adantr 480 | . . . . . . . . . . 11
⊢ ((𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) ∧ 𝐴 ⊆ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵)) → (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵) ∈ V) | 
| 22 |  | simpr 484 | . . . . . . . . . . 11
⊢ ((𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) ∧ 𝐴 ⊆ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵)) → 𝐴 ⊆ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵)) | 
| 23 |  | ssdomg 9040 | . . . . . . . . . . 11
⊢
((((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵) ∈ V → (𝐴 ⊆ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵) → 𝐴 ≼ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵))) | 
| 24 | 21, 22, 23 | sylc 65 | . . . . . . . . . 10
⊢ ((𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) ∧ 𝐴 ⊆ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵)) → 𝐴 ≼ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵)) | 
| 25 |  | domwdom 9614 | . . . . . . . . . 10
⊢ (𝐴 ≼ (((1st
↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵) → 𝐴 ≼* (((1st
↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵)) | 
| 26 | 24, 25 | syl 17 | . . . . . . . . 9
⊢ ((𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) ∧ 𝐴 ⊆ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵)) → 𝐴 ≼* (((1st
↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵)) | 
| 27 | 17 | ffund 6740 | . . . . . . . . . . 11
⊢ (𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) → Fun ((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓)) | 
| 28 |  | ssun1 4178 | . . . . . . . . . . . 12
⊢ 𝐵 ⊆ (𝐵 ∪ 𝐶) | 
| 29 |  | f1odm 6852 | . . . . . . . . . . . . 13
⊢ (𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) → dom 𝑓 = (𝐵 ∪ 𝐶)) | 
| 30 | 8 | dmex 7931 | . . . . . . . . . . . . 13
⊢ dom 𝑓 ∈ V | 
| 31 | 29, 30 | eqeltrrdi 2850 | . . . . . . . . . . . 12
⊢ (𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) → (𝐵 ∪ 𝐶) ∈ V) | 
| 32 |  | ssexg 5323 | . . . . . . . . . . . 12
⊢ ((𝐵 ⊆ (𝐵 ∪ 𝐶) ∧ (𝐵 ∪ 𝐶) ∈ V) → 𝐵 ∈ V) | 
| 33 | 28, 31, 32 | sylancr 587 | . . . . . . . . . . 11
⊢ (𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) → 𝐵 ∈ V) | 
| 34 |  | wdomima2g 9626 | . . . . . . . . . . 11
⊢ ((Fun
((1st ↾ (𝐴
× 𝐴)) ∘ 𝑓) ∧ 𝐵 ∈ V ∧ (((1st ↾
(𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵) ∈ V) → (((1st ↾
(𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵) ≼* 𝐵) | 
| 35 | 27, 33, 20, 34 | syl3anc 1373 | . . . . . . . . . 10
⊢ (𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) → (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵) ≼* 𝐵) | 
| 36 | 35 | adantr 480 | . . . . . . . . 9
⊢ ((𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) ∧ 𝐴 ⊆ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵)) → (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵) ≼* 𝐵) | 
| 37 |  | wdomtr 9615 | . . . . . . . . 9
⊢ ((𝐴 ≼*
(((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵) ∧ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵) ≼* 𝐵) → 𝐴 ≼* 𝐵) | 
| 38 | 26, 36, 37 | syl2anc 584 | . . . . . . . 8
⊢ ((𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) ∧ 𝐴 ⊆ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵)) → 𝐴 ≼* 𝐵) | 
| 39 | 38 | orcd 874 | . . . . . . 7
⊢ ((𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) ∧ 𝐴 ⊆ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵)) → (𝐴 ≼* 𝐵 ∨ 𝐴 ≼ 𝐶)) | 
| 40 | 39 | ex 412 | . . . . . 6
⊢ (𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) → (𝐴 ⊆ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵) → (𝐴 ≼* 𝐵 ∨ 𝐴 ≼ 𝐶))) | 
| 41 | 3, 40 | biimtrrid 243 | . . . . 5
⊢ (𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) → ((𝐴 ∖ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵)) = ∅ → (𝐴 ≼* 𝐵 ∨ 𝐴 ≼ 𝐶))) | 
| 42 |  | n0 4353 | . . . . . 6
⊢ ((𝐴 ∖ (((1st
↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵)) ≠ ∅ ↔ ∃𝑥 𝑥 ∈ (𝐴 ∖ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵))) | 
| 43 |  | ssun2 4179 | . . . . . . . . . . . . 13
⊢ 𝐶 ⊆ (𝐵 ∪ 𝐶) | 
| 44 |  | ssexg 5323 | . . . . . . . . . . . . 13
⊢ ((𝐶 ⊆ (𝐵 ∪ 𝐶) ∧ (𝐵 ∪ 𝐶) ∈ V) → 𝐶 ∈ V) | 
| 45 | 43, 31, 44 | sylancr 587 | . . . . . . . . . . . 12
⊢ (𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) → 𝐶 ∈ V) | 
| 46 | 45 | adantr 480 | . . . . . . . . . . 11
⊢ ((𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) ∧ 𝑥 ∈ (𝐴 ∖ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵))) → 𝐶 ∈ V) | 
| 47 |  | f1ofn 6849 | . . . . . . . . . . . . . . 15
⊢ (𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) → 𝑓 Fn (𝐵 ∪ 𝐶)) | 
| 48 |  | elpreima 7078 | . . . . . . . . . . . . . . 15
⊢ (𝑓 Fn (𝐵 ∪ 𝐶) → (𝑦 ∈ (◡𝑓 “ ({𝑥} × 𝐴)) ↔ (𝑦 ∈ (𝐵 ∪ 𝐶) ∧ (𝑓‘𝑦) ∈ ({𝑥} × 𝐴)))) | 
| 49 | 47, 48 | syl 17 | . . . . . . . . . . . . . 14
⊢ (𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) → (𝑦 ∈ (◡𝑓 “ ({𝑥} × 𝐴)) ↔ (𝑦 ∈ (𝐵 ∪ 𝐶) ∧ (𝑓‘𝑦) ∈ ({𝑥} × 𝐴)))) | 
| 50 | 49 | adantr 480 | . . . . . . . . . . . . 13
⊢ ((𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) ∧ 𝑥 ∈ (𝐴 ∖ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵))) → (𝑦 ∈ (◡𝑓 “ ({𝑥} × 𝐴)) ↔ (𝑦 ∈ (𝐵 ∪ 𝐶) ∧ (𝑓‘𝑦) ∈ ({𝑥} × 𝐴)))) | 
| 51 |  | elun 4153 | . . . . . . . . . . . . . . . 16
⊢ (𝑦 ∈ (𝐵 ∪ 𝐶) ↔ (𝑦 ∈ 𝐵 ∨ 𝑦 ∈ 𝐶)) | 
| 52 |  | df-or 849 | . . . . . . . . . . . . . . . 16
⊢ ((𝑦 ∈ 𝐵 ∨ 𝑦 ∈ 𝐶) ↔ (¬ 𝑦 ∈ 𝐵 → 𝑦 ∈ 𝐶)) | 
| 53 | 51, 52 | bitri 275 | . . . . . . . . . . . . . . 15
⊢ (𝑦 ∈ (𝐵 ∪ 𝐶) ↔ (¬ 𝑦 ∈ 𝐵 → 𝑦 ∈ 𝐶)) | 
| 54 |  | eldifn 4132 | . . . . . . . . . . . . . . . . . . 19
⊢ (𝑥 ∈ (𝐴 ∖ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵)) → ¬ 𝑥 ∈ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵)) | 
| 55 | 54 | ad2antlr 727 | . . . . . . . . . . . . . . . . . 18
⊢ (((𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) ∧ 𝑥 ∈ (𝐴 ∖ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵))) ∧ (𝑓‘𝑦) ∈ ({𝑥} × 𝐴)) → ¬ 𝑥 ∈ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵)) | 
| 56 | 15 | ad2antrr 726 | . . . . . . . . . . . . . . . . . . . . . 22
⊢ (((𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) ∧ 𝑥 ∈ (𝐴 ∖ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵))) ∧ ((𝑓‘𝑦) ∈ ({𝑥} × 𝐴) ∧ 𝑦 ∈ 𝐵)) → 𝑓:(𝐵 ∪ 𝐶)⟶(𝐴 × 𝐴)) | 
| 57 |  | simprr 773 | . . . . . . . . . . . . . . . . . . . . . . 23
⊢ (((𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) ∧ 𝑥 ∈ (𝐴 ∖ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵))) ∧ ((𝑓‘𝑦) ∈ ({𝑥} × 𝐴) ∧ 𝑦 ∈ 𝐵)) → 𝑦 ∈ 𝐵) | 
| 58 | 28, 57 | sselid 3981 | . . . . . . . . . . . . . . . . . . . . . 22
⊢ (((𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) ∧ 𝑥 ∈ (𝐴 ∖ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵))) ∧ ((𝑓‘𝑦) ∈ ({𝑥} × 𝐴) ∧ 𝑦 ∈ 𝐵)) → 𝑦 ∈ (𝐵 ∪ 𝐶)) | 
| 59 |  | fvco3 7008 | . . . . . . . . . . . . . . . . . . . . . 22
⊢ ((𝑓:(𝐵 ∪ 𝐶)⟶(𝐴 × 𝐴) ∧ 𝑦 ∈ (𝐵 ∪ 𝐶)) → (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓)‘𝑦) = ((1st ↾ (𝐴 × 𝐴))‘(𝑓‘𝑦))) | 
| 60 | 56, 58, 59 | syl2anc 584 | . . . . . . . . . . . . . . . . . . . . 21
⊢ (((𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) ∧ 𝑥 ∈ (𝐴 ∖ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵))) ∧ ((𝑓‘𝑦) ∈ ({𝑥} × 𝐴) ∧ 𝑦 ∈ 𝐵)) → (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓)‘𝑦) = ((1st ↾ (𝐴 × 𝐴))‘(𝑓‘𝑦))) | 
| 61 |  | eldifi 4131 | . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
⊢ (𝑥 ∈ (𝐴 ∖ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵)) → 𝑥 ∈ 𝐴) | 
| 62 | 61 | adantl 481 | . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
⊢ ((𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) ∧ 𝑥 ∈ (𝐴 ∖ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵))) → 𝑥 ∈ 𝐴) | 
| 63 | 62 | snssd 4809 | . . . . . . . . . . . . . . . . . . . . . . . . . . 27
⊢ ((𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) ∧ 𝑥 ∈ (𝐴 ∖ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵))) → {𝑥} ⊆ 𝐴) | 
| 64 |  | xpss1 5704 | . . . . . . . . . . . . . . . . . . . . . . . . . . 27
⊢ ({𝑥} ⊆ 𝐴 → ({𝑥} × 𝐴) ⊆ (𝐴 × 𝐴)) | 
| 65 | 63, 64 | syl 17 | . . . . . . . . . . . . . . . . . . . . . . . . . 26
⊢ ((𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) ∧ 𝑥 ∈ (𝐴 ∖ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵))) → ({𝑥} × 𝐴) ⊆ (𝐴 × 𝐴)) | 
| 66 | 65 | adantr 480 | . . . . . . . . . . . . . . . . . . . . . . . . 25
⊢ (((𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) ∧ 𝑥 ∈ (𝐴 ∖ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵))) ∧ ((𝑓‘𝑦) ∈ ({𝑥} × 𝐴) ∧ 𝑦 ∈ 𝐵)) → ({𝑥} × 𝐴) ⊆ (𝐴 × 𝐴)) | 
| 67 |  | simprl 771 | . . . . . . . . . . . . . . . . . . . . . . . . 25
⊢ (((𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) ∧ 𝑥 ∈ (𝐴 ∖ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵))) ∧ ((𝑓‘𝑦) ∈ ({𝑥} × 𝐴) ∧ 𝑦 ∈ 𝐵)) → (𝑓‘𝑦) ∈ ({𝑥} × 𝐴)) | 
| 68 | 66, 67 | sseldd 3984 | . . . . . . . . . . . . . . . . . . . . . . . 24
⊢ (((𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) ∧ 𝑥 ∈ (𝐴 ∖ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵))) ∧ ((𝑓‘𝑦) ∈ ({𝑥} × 𝐴) ∧ 𝑦 ∈ 𝐵)) → (𝑓‘𝑦) ∈ (𝐴 × 𝐴)) | 
| 69 | 68 | fvresd 6926 | . . . . . . . . . . . . . . . . . . . . . . 23
⊢ (((𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) ∧ 𝑥 ∈ (𝐴 ∖ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵))) ∧ ((𝑓‘𝑦) ∈ ({𝑥} × 𝐴) ∧ 𝑦 ∈ 𝐵)) → ((1st ↾ (𝐴 × 𝐴))‘(𝑓‘𝑦)) = (1st ‘(𝑓‘𝑦))) | 
| 70 |  | xp1st 8046 | . . . . . . . . . . . . . . . . . . . . . . . 24
⊢ ((𝑓‘𝑦) ∈ ({𝑥} × 𝐴) → (1st ‘(𝑓‘𝑦)) ∈ {𝑥}) | 
| 71 | 67, 70 | syl 17 | . . . . . . . . . . . . . . . . . . . . . . 23
⊢ (((𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) ∧ 𝑥 ∈ (𝐴 ∖ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵))) ∧ ((𝑓‘𝑦) ∈ ({𝑥} × 𝐴) ∧ 𝑦 ∈ 𝐵)) → (1st ‘(𝑓‘𝑦)) ∈ {𝑥}) | 
| 72 | 69, 71 | eqeltrd 2841 | . . . . . . . . . . . . . . . . . . . . . 22
⊢ (((𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) ∧ 𝑥 ∈ (𝐴 ∖ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵))) ∧ ((𝑓‘𝑦) ∈ ({𝑥} × 𝐴) ∧ 𝑦 ∈ 𝐵)) → ((1st ↾ (𝐴 × 𝐴))‘(𝑓‘𝑦)) ∈ {𝑥}) | 
| 73 |  | elsni 4643 | . . . . . . . . . . . . . . . . . . . . . 22
⊢
(((1st ↾ (𝐴 × 𝐴))‘(𝑓‘𝑦)) ∈ {𝑥} → ((1st ↾ (𝐴 × 𝐴))‘(𝑓‘𝑦)) = 𝑥) | 
| 74 | 72, 73 | syl 17 | . . . . . . . . . . . . . . . . . . . . 21
⊢ (((𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) ∧ 𝑥 ∈ (𝐴 ∖ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵))) ∧ ((𝑓‘𝑦) ∈ ({𝑥} × 𝐴) ∧ 𝑦 ∈ 𝐵)) → ((1st ↾ (𝐴 × 𝐴))‘(𝑓‘𝑦)) = 𝑥) | 
| 75 | 60, 74 | eqtrd 2777 | . . . . . . . . . . . . . . . . . . . 20
⊢ (((𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) ∧ 𝑥 ∈ (𝐴 ∖ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵))) ∧ ((𝑓‘𝑦) ∈ ({𝑥} × 𝐴) ∧ 𝑦 ∈ 𝐵)) → (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓)‘𝑦) = 𝑥) | 
| 76 | 17 | ffnd 6737 | . . . . . . . . . . . . . . . . . . . . . 22
⊢ (𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) → ((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) Fn (𝐵 ∪ 𝐶)) | 
| 77 | 76 | ad2antrr 726 | . . . . . . . . . . . . . . . . . . . . 21
⊢ (((𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) ∧ 𝑥 ∈ (𝐴 ∖ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵))) ∧ ((𝑓‘𝑦) ∈ ({𝑥} × 𝐴) ∧ 𝑦 ∈ 𝐵)) → ((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) Fn (𝐵 ∪ 𝐶)) | 
| 78 | 28 | a1i 11 | . . . . . . . . . . . . . . . . . . . . 21
⊢ (((𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) ∧ 𝑥 ∈ (𝐴 ∖ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵))) ∧ ((𝑓‘𝑦) ∈ ({𝑥} × 𝐴) ∧ 𝑦 ∈ 𝐵)) → 𝐵 ⊆ (𝐵 ∪ 𝐶)) | 
| 79 |  | fnfvima 7253 | . . . . . . . . . . . . . . . . . . . . 21
⊢
((((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) Fn (𝐵 ∪ 𝐶) ∧ 𝐵 ⊆ (𝐵 ∪ 𝐶) ∧ 𝑦 ∈ 𝐵) → (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓)‘𝑦) ∈ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵)) | 
| 80 | 77, 78, 57, 79 | syl3anc 1373 | . . . . . . . . . . . . . . . . . . . 20
⊢ (((𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) ∧ 𝑥 ∈ (𝐴 ∖ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵))) ∧ ((𝑓‘𝑦) ∈ ({𝑥} × 𝐴) ∧ 𝑦 ∈ 𝐵)) → (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓)‘𝑦) ∈ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵)) | 
| 81 | 75, 80 | eqeltrrd 2842 | . . . . . . . . . . . . . . . . . . 19
⊢ (((𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) ∧ 𝑥 ∈ (𝐴 ∖ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵))) ∧ ((𝑓‘𝑦) ∈ ({𝑥} × 𝐴) ∧ 𝑦 ∈ 𝐵)) → 𝑥 ∈ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵)) | 
| 82 | 81 | expr 456 | . . . . . . . . . . . . . . . . . 18
⊢ (((𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) ∧ 𝑥 ∈ (𝐴 ∖ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵))) ∧ (𝑓‘𝑦) ∈ ({𝑥} × 𝐴)) → (𝑦 ∈ 𝐵 → 𝑥 ∈ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵))) | 
| 83 | 55, 82 | mtod 198 | . . . . . . . . . . . . . . . . 17
⊢ (((𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) ∧ 𝑥 ∈ (𝐴 ∖ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵))) ∧ (𝑓‘𝑦) ∈ ({𝑥} × 𝐴)) → ¬ 𝑦 ∈ 𝐵) | 
| 84 | 83 | ex 412 | . . . . . . . . . . . . . . . 16
⊢ ((𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) ∧ 𝑥 ∈ (𝐴 ∖ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵))) → ((𝑓‘𝑦) ∈ ({𝑥} × 𝐴) → ¬ 𝑦 ∈ 𝐵)) | 
| 85 | 84 | imim1d 82 | . . . . . . . . . . . . . . 15
⊢ ((𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) ∧ 𝑥 ∈ (𝐴 ∖ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵))) → ((¬ 𝑦 ∈ 𝐵 → 𝑦 ∈ 𝐶) → ((𝑓‘𝑦) ∈ ({𝑥} × 𝐴) → 𝑦 ∈ 𝐶))) | 
| 86 | 53, 85 | biimtrid 242 | . . . . . . . . . . . . . 14
⊢ ((𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) ∧ 𝑥 ∈ (𝐴 ∖ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵))) → (𝑦 ∈ (𝐵 ∪ 𝐶) → ((𝑓‘𝑦) ∈ ({𝑥} × 𝐴) → 𝑦 ∈ 𝐶))) | 
| 87 | 86 | impd 410 | . . . . . . . . . . . . 13
⊢ ((𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) ∧ 𝑥 ∈ (𝐴 ∖ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵))) → ((𝑦 ∈ (𝐵 ∪ 𝐶) ∧ (𝑓‘𝑦) ∈ ({𝑥} × 𝐴)) → 𝑦 ∈ 𝐶)) | 
| 88 | 50, 87 | sylbid 240 | . . . . . . . . . . . 12
⊢ ((𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) ∧ 𝑥 ∈ (𝐴 ∖ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵))) → (𝑦 ∈ (◡𝑓 “ ({𝑥} × 𝐴)) → 𝑦 ∈ 𝐶)) | 
| 89 | 88 | ssrdv 3989 | . . . . . . . . . . 11
⊢ ((𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) ∧ 𝑥 ∈ (𝐴 ∖ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵))) → (◡𝑓 “ ({𝑥} × 𝐴)) ⊆ 𝐶) | 
| 90 |  | ssdomg 9040 | . . . . . . . . . . 11
⊢ (𝐶 ∈ V → ((◡𝑓 “ ({𝑥} × 𝐴)) ⊆ 𝐶 → (◡𝑓 “ ({𝑥} × 𝐴)) ≼ 𝐶)) | 
| 91 | 46, 89, 90 | sylc 65 | . . . . . . . . . 10
⊢ ((𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) ∧ 𝑥 ∈ (𝐴 ∖ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵))) → (◡𝑓 “ ({𝑥} × 𝐴)) ≼ 𝐶) | 
| 92 |  | f1ocnv 6860 | . . . . . . . . . . . . . . 15
⊢ (𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) → ◡𝑓:(𝐴 × 𝐴)–1-1-onto→(𝐵 ∪ 𝐶)) | 
| 93 |  | f1of1 6847 | . . . . . . . . . . . . . . 15
⊢ (◡𝑓:(𝐴 × 𝐴)–1-1-onto→(𝐵 ∪ 𝐶) → ◡𝑓:(𝐴 × 𝐴)–1-1→(𝐵 ∪ 𝐶)) | 
| 94 | 92, 93 | syl 17 | . . . . . . . . . . . . . 14
⊢ (𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) → ◡𝑓:(𝐴 × 𝐴)–1-1→(𝐵 ∪ 𝐶)) | 
| 95 | 94 | adantr 480 | . . . . . . . . . . . . 13
⊢ ((𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) ∧ 𝑥 ∈ (𝐴 ∖ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵))) → ◡𝑓:(𝐴 × 𝐴)–1-1→(𝐵 ∪ 𝐶)) | 
| 96 | 31 | adantr 480 | . . . . . . . . . . . . 13
⊢ ((𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) ∧ 𝑥 ∈ (𝐴 ∖ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵))) → (𝐵 ∪ 𝐶) ∈ V) | 
| 97 |  | vsnex 5434 | . . . . . . . . . . . . . 14
⊢ {𝑥} ∈ V | 
| 98 | 12 | adantr 480 | . . . . . . . . . . . . . 14
⊢ ((𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) ∧ 𝑥 ∈ (𝐴 ∖ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵))) → 𝐴 ∈ V) | 
| 99 |  | xpexg 7770 | . . . . . . . . . . . . . 14
⊢ (({𝑥} ∈ V ∧ 𝐴 ∈ V) → ({𝑥} × 𝐴) ∈ V) | 
| 100 | 97, 98, 99 | sylancr 587 | . . . . . . . . . . . . 13
⊢ ((𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) ∧ 𝑥 ∈ (𝐴 ∖ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵))) → ({𝑥} × 𝐴) ∈ V) | 
| 101 |  | f1imaen2g 9055 | . . . . . . . . . . . . 13
⊢ (((◡𝑓:(𝐴 × 𝐴)–1-1→(𝐵 ∪ 𝐶) ∧ (𝐵 ∪ 𝐶) ∈ V) ∧ (({𝑥} × 𝐴) ⊆ (𝐴 × 𝐴) ∧ ({𝑥} × 𝐴) ∈ V)) → (◡𝑓 “ ({𝑥} × 𝐴)) ≈ ({𝑥} × 𝐴)) | 
| 102 | 95, 96, 65, 100, 101 | syl22anc 839 | . . . . . . . . . . . 12
⊢ ((𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) ∧ 𝑥 ∈ (𝐴 ∖ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵))) → (◡𝑓 “ ({𝑥} × 𝐴)) ≈ ({𝑥} × 𝐴)) | 
| 103 |  | vex 3484 | . . . . . . . . . . . . 13
⊢ 𝑥 ∈ V | 
| 104 |  | xpsnen2g 9105 | . . . . . . . . . . . . 13
⊢ ((𝑥 ∈ V ∧ 𝐴 ∈ V) → ({𝑥} × 𝐴) ≈ 𝐴) | 
| 105 | 103, 98, 104 | sylancr 587 | . . . . . . . . . . . 12
⊢ ((𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) ∧ 𝑥 ∈ (𝐴 ∖ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵))) → ({𝑥} × 𝐴) ≈ 𝐴) | 
| 106 |  | entr 9046 | . . . . . . . . . . . 12
⊢ (((◡𝑓 “ ({𝑥} × 𝐴)) ≈ ({𝑥} × 𝐴) ∧ ({𝑥} × 𝐴) ≈ 𝐴) → (◡𝑓 “ ({𝑥} × 𝐴)) ≈ 𝐴) | 
| 107 | 102, 105,
106 | syl2anc 584 | . . . . . . . . . . 11
⊢ ((𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) ∧ 𝑥 ∈ (𝐴 ∖ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵))) → (◡𝑓 “ ({𝑥} × 𝐴)) ≈ 𝐴) | 
| 108 |  | domen1 9159 | . . . . . . . . . . 11
⊢ ((◡𝑓 “ ({𝑥} × 𝐴)) ≈ 𝐴 → ((◡𝑓 “ ({𝑥} × 𝐴)) ≼ 𝐶 ↔ 𝐴 ≼ 𝐶)) | 
| 109 | 107, 108 | syl 17 | . . . . . . . . . 10
⊢ ((𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) ∧ 𝑥 ∈ (𝐴 ∖ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵))) → ((◡𝑓 “ ({𝑥} × 𝐴)) ≼ 𝐶 ↔ 𝐴 ≼ 𝐶)) | 
| 110 | 91, 109 | mpbid 232 | . . . . . . . . 9
⊢ ((𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) ∧ 𝑥 ∈ (𝐴 ∖ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵))) → 𝐴 ≼ 𝐶) | 
| 111 | 110 | olcd 875 | . . . . . . . 8
⊢ ((𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) ∧ 𝑥 ∈ (𝐴 ∖ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵))) → (𝐴 ≼* 𝐵 ∨ 𝐴 ≼ 𝐶)) | 
| 112 | 111 | ex 412 | . . . . . . 7
⊢ (𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) → (𝑥 ∈ (𝐴 ∖ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵)) → (𝐴 ≼* 𝐵 ∨ 𝐴 ≼ 𝐶))) | 
| 113 | 112 | exlimdv 1933 | . . . . . 6
⊢ (𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) → (∃𝑥 𝑥 ∈ (𝐴 ∖ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵)) → (𝐴 ≼* 𝐵 ∨ 𝐴 ≼ 𝐶))) | 
| 114 | 42, 113 | biimtrid 242 | . . . . 5
⊢ (𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) → ((𝐴 ∖ (((1st ↾ (𝐴 × 𝐴)) ∘ 𝑓) “ 𝐵)) ≠ ∅ → (𝐴 ≼* 𝐵 ∨ 𝐴 ≼ 𝐶))) | 
| 115 | 41, 114 | pm2.61dne 3028 | . . . 4
⊢ (𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) → (𝐴 ≼* 𝐵 ∨ 𝐴 ≼ 𝐶)) | 
| 116 | 115 | exlimiv 1930 | . . 3
⊢
(∃𝑓 𝑓:(𝐵 ∪ 𝐶)–1-1-onto→(𝐴 × 𝐴) → (𝐴 ≼* 𝐵 ∨ 𝐴 ≼ 𝐶)) | 
| 117 | 2, 116 | sylbi 217 | . 2
⊢ ((𝐵 ∪ 𝐶) ≈ (𝐴 × 𝐴) → (𝐴 ≼* 𝐵 ∨ 𝐴 ≼ 𝐶)) | 
| 118 | 1, 117 | syl 17 | 1
⊢ ((𝐴 × 𝐴) ≈ (𝐵 ∪ 𝐶) → (𝐴 ≼* 𝐵 ∨ 𝐴 ≼ 𝐶)) |