| Step | Hyp | Ref | Expression | 
|---|
| 1 |  | feq1 6715 | . . . . 5
⊢ (𝑔 = 𝐺 → (𝑔:(𝑡 × 𝑡)⟶𝑡 ↔ 𝐺:(𝑡 × 𝑡)⟶𝑡)) | 
| 2 | 1 | exbidv 1920 | . . . 4
⊢ (𝑔 = 𝐺 → (∃𝑡 𝑔:(𝑡 × 𝑡)⟶𝑡 ↔ ∃𝑡 𝐺:(𝑡 × 𝑡)⟶𝑡)) | 
| 3 |  | df-mgmOLD 37857 | . . . 4
⊢ Magma =
{𝑔 ∣ ∃𝑡 𝑔:(𝑡 × 𝑡)⟶𝑡} | 
| 4 | 2, 3 | elab2g 3679 | . . 3
⊢ (𝐺 ∈ 𝐴 → (𝐺 ∈ Magma ↔ ∃𝑡 𝐺:(𝑡 × 𝑡)⟶𝑡)) | 
| 5 |  | f00 6789 | . . . . . . . 8
⊢ (𝐺:(∅ ×
∅)⟶∅ ↔ (𝐺 = ∅ ∧ (∅ × ∅) =
∅)) | 
| 6 |  | dmeq 5913 | . . . . . . . . . 10
⊢ (𝐺 = ∅ → dom 𝐺 = dom ∅) | 
| 7 |  | dmeq 5913 | . . . . . . . . . . 11
⊢ (dom
𝐺 = dom ∅ → dom
dom 𝐺 = dom dom
∅) | 
| 8 |  | dm0 5930 | . . . . . . . . . . . . 13
⊢ dom
∅ = ∅ | 
| 9 | 8 | dmeqi 5914 | . . . . . . . . . . . 12
⊢ dom dom
∅ = dom ∅ | 
| 10 | 9, 8 | eqtri 2764 | . . . . . . . . . . 11
⊢ dom dom
∅ = ∅ | 
| 11 | 7, 10 | eqtr2di 2793 | . . . . . . . . . 10
⊢ (dom
𝐺 = dom ∅ →
∅ = dom dom 𝐺) | 
| 12 | 6, 11 | syl 17 | . . . . . . . . 9
⊢ (𝐺 = ∅ → ∅ = dom
dom 𝐺) | 
| 13 | 12 | adantr 480 | . . . . . . . 8
⊢ ((𝐺 = ∅ ∧ (∅
× ∅) = ∅) → ∅ = dom dom 𝐺) | 
| 14 | 5, 13 | sylbi 217 | . . . . . . 7
⊢ (𝐺:(∅ ×
∅)⟶∅ → ∅ = dom dom 𝐺) | 
| 15 |  | xpeq12 5709 | . . . . . . . . . 10
⊢ ((𝑡 = ∅ ∧ 𝑡 = ∅) → (𝑡 × 𝑡) = (∅ ×
∅)) | 
| 16 | 15 | anidms 566 | . . . . . . . . 9
⊢ (𝑡 = ∅ → (𝑡 × 𝑡) = (∅ ×
∅)) | 
| 17 |  | feq23 6718 | . . . . . . . . 9
⊢ (((𝑡 × 𝑡) = (∅ × ∅) ∧ 𝑡 = ∅) → (𝐺:(𝑡 × 𝑡)⟶𝑡 ↔ 𝐺:(∅ ×
∅)⟶∅)) | 
| 18 | 16, 17 | mpancom 688 | . . . . . . . 8
⊢ (𝑡 = ∅ → (𝐺:(𝑡 × 𝑡)⟶𝑡 ↔ 𝐺:(∅ ×
∅)⟶∅)) | 
| 19 |  | eqeq1 2740 | . . . . . . . 8
⊢ (𝑡 = ∅ → (𝑡 = dom dom 𝐺 ↔ ∅ = dom dom 𝐺)) | 
| 20 | 18, 19 | imbi12d 344 | . . . . . . 7
⊢ (𝑡 = ∅ → ((𝐺:(𝑡 × 𝑡)⟶𝑡 → 𝑡 = dom dom 𝐺) ↔ (𝐺:(∅ × ∅)⟶∅
→ ∅ = dom dom 𝐺))) | 
| 21 | 14, 20 | mpbiri 258 | . . . . . 6
⊢ (𝑡 = ∅ → (𝐺:(𝑡 × 𝑡)⟶𝑡 → 𝑡 = dom dom 𝐺)) | 
| 22 |  | fdm 6744 | . . . . . . . 8
⊢ (𝐺:(𝑡 × 𝑡)⟶𝑡 → dom 𝐺 = (𝑡 × 𝑡)) | 
| 23 |  | dmeq 5913 | . . . . . . . 8
⊢ (dom
𝐺 = (𝑡 × 𝑡) → dom dom 𝐺 = dom (𝑡 × 𝑡)) | 
| 24 |  | df-ne 2940 | . . . . . . . . . . . 12
⊢ (𝑡 ≠ ∅ ↔ ¬ 𝑡 = ∅) | 
| 25 |  | dmxp 5938 | . . . . . . . . . . . 12
⊢ (𝑡 ≠ ∅ → dom (𝑡 × 𝑡) = 𝑡) | 
| 26 | 24, 25 | sylbir 235 | . . . . . . . . . . 11
⊢ (¬
𝑡 = ∅ → dom
(𝑡 × 𝑡) = 𝑡) | 
| 27 | 26 | eqeq1d 2738 | . . . . . . . . . 10
⊢ (¬
𝑡 = ∅ → (dom
(𝑡 × 𝑡) = dom dom 𝐺 ↔ 𝑡 = dom dom 𝐺)) | 
| 28 | 27 | biimpcd 249 | . . . . . . . . 9
⊢ (dom
(𝑡 × 𝑡) = dom dom 𝐺 → (¬ 𝑡 = ∅ → 𝑡 = dom dom 𝐺)) | 
| 29 | 28 | eqcoms 2744 | . . . . . . . 8
⊢ (dom dom
𝐺 = dom (𝑡 × 𝑡) → (¬ 𝑡 = ∅ → 𝑡 = dom dom 𝐺)) | 
| 30 | 22, 23, 29 | 3syl 18 | . . . . . . 7
⊢ (𝐺:(𝑡 × 𝑡)⟶𝑡 → (¬ 𝑡 = ∅ → 𝑡 = dom dom 𝐺)) | 
| 31 | 30 | com12 32 | . . . . . 6
⊢ (¬
𝑡 = ∅ → (𝐺:(𝑡 × 𝑡)⟶𝑡 → 𝑡 = dom dom 𝐺)) | 
| 32 | 21, 31 | pm2.61i 182 | . . . . 5
⊢ (𝐺:(𝑡 × 𝑡)⟶𝑡 → 𝑡 = dom dom 𝐺) | 
| 33 | 32 | pm4.71ri 560 | . . . 4
⊢ (𝐺:(𝑡 × 𝑡)⟶𝑡 ↔ (𝑡 = dom dom 𝐺 ∧ 𝐺:(𝑡 × 𝑡)⟶𝑡)) | 
| 34 | 33 | exbii 1847 | . . 3
⊢
(∃𝑡 𝐺:(𝑡 × 𝑡)⟶𝑡 ↔ ∃𝑡(𝑡 = dom dom 𝐺 ∧ 𝐺:(𝑡 × 𝑡)⟶𝑡)) | 
| 35 | 4, 34 | bitrdi 287 | . 2
⊢ (𝐺 ∈ 𝐴 → (𝐺 ∈ Magma ↔ ∃𝑡(𝑡 = dom dom 𝐺 ∧ 𝐺:(𝑡 × 𝑡)⟶𝑡))) | 
| 36 |  | dmexg 7924 | . . 3
⊢ (𝐺 ∈ 𝐴 → dom 𝐺 ∈ V) | 
| 37 |  | dmexg 7924 | . . 3
⊢ (dom
𝐺 ∈ V → dom dom
𝐺 ∈
V) | 
| 38 |  | xpeq12 5709 | . . . . . . 7
⊢ ((𝑡 = dom dom 𝐺 ∧ 𝑡 = dom dom 𝐺) → (𝑡 × 𝑡) = (dom dom 𝐺 × dom dom 𝐺)) | 
| 39 | 38 | anidms 566 | . . . . . 6
⊢ (𝑡 = dom dom 𝐺 → (𝑡 × 𝑡) = (dom dom 𝐺 × dom dom 𝐺)) | 
| 40 |  | feq23 6718 | . . . . . 6
⊢ (((𝑡 × 𝑡) = (dom dom 𝐺 × dom dom 𝐺) ∧ 𝑡 = dom dom 𝐺) → (𝐺:(𝑡 × 𝑡)⟶𝑡 ↔ 𝐺:(dom dom 𝐺 × dom dom 𝐺)⟶dom dom 𝐺)) | 
| 41 | 39, 40 | mpancom 688 | . . . . 5
⊢ (𝑡 = dom dom 𝐺 → (𝐺:(𝑡 × 𝑡)⟶𝑡 ↔ 𝐺:(dom dom 𝐺 × dom dom 𝐺)⟶dom dom 𝐺)) | 
| 42 |  | ismgmOLD.1 | . . . . . . . 8
⊢ 𝑋 = dom dom 𝐺 | 
| 43 | 42 | eqcomi 2745 | . . . . . . 7
⊢ dom dom
𝐺 = 𝑋 | 
| 44 | 43, 43 | xpeq12i 5712 | . . . . . 6
⊢ (dom dom
𝐺 × dom dom 𝐺) = (𝑋 × 𝑋) | 
| 45 | 44, 43 | feq23i 6729 | . . . . 5
⊢ (𝐺:(dom dom 𝐺 × dom dom 𝐺)⟶dom dom 𝐺 ↔ 𝐺:(𝑋 × 𝑋)⟶𝑋) | 
| 46 | 41, 45 | bitrdi 287 | . . . 4
⊢ (𝑡 = dom dom 𝐺 → (𝐺:(𝑡 × 𝑡)⟶𝑡 ↔ 𝐺:(𝑋 × 𝑋)⟶𝑋)) | 
| 47 | 46 | ceqsexgv 3653 | . . 3
⊢ (dom dom
𝐺 ∈ V →
(∃𝑡(𝑡 = dom dom 𝐺 ∧ 𝐺:(𝑡 × 𝑡)⟶𝑡) ↔ 𝐺:(𝑋 × 𝑋)⟶𝑋)) | 
| 48 | 36, 37, 47 | 3syl 18 | . 2
⊢ (𝐺 ∈ 𝐴 → (∃𝑡(𝑡 = dom dom 𝐺 ∧ 𝐺:(𝑡 × 𝑡)⟶𝑡) ↔ 𝐺:(𝑋 × 𝑋)⟶𝑋)) | 
| 49 | 35, 48 | bitrd 279 | 1
⊢ (𝐺 ∈ 𝐴 → (𝐺 ∈ Magma ↔ 𝐺:(𝑋 × 𝑋)⟶𝑋)) |