| Step | Hyp | Ref
 | Expression | 
| 1 |   | grpinva.r | 
. . . . 5
⊢ ((𝜑 ∧ 𝑥 ∈ 𝐵) → ∃𝑦 ∈ 𝐵 (𝑦 + 𝑥) = 𝑂) | 
| 2 | 1 | ralrimiva 2570 | 
. . . 4
⊢ (𝜑 → ∀𝑥 ∈ 𝐵 ∃𝑦 ∈ 𝐵 (𝑦 + 𝑥) = 𝑂) | 
| 3 |   | oveq2 5930 | 
. . . . . . 7
⊢ (𝑥 = 𝑧 → (𝑦 + 𝑥) = (𝑦 + 𝑧)) | 
| 4 | 3 | eqeq1d 2205 | 
. . . . . 6
⊢ (𝑥 = 𝑧 → ((𝑦 + 𝑥) = 𝑂 ↔ (𝑦 + 𝑧) = 𝑂)) | 
| 5 | 4 | rexbidv 2498 | 
. . . . 5
⊢ (𝑥 = 𝑧 → (∃𝑦 ∈ 𝐵 (𝑦 + 𝑥) = 𝑂 ↔ ∃𝑦 ∈ 𝐵 (𝑦 + 𝑧) = 𝑂)) | 
| 6 | 5 | cbvralvw 2733 | 
. . . 4
⊢
(∀𝑥 ∈
𝐵 ∃𝑦 ∈ 𝐵 (𝑦 + 𝑥) = 𝑂 ↔ ∀𝑧 ∈ 𝐵 ∃𝑦 ∈ 𝐵 (𝑦 + 𝑧) = 𝑂) | 
| 7 | 2, 6 | sylib 122 | 
. . 3
⊢ (𝜑 → ∀𝑧 ∈ 𝐵 ∃𝑦 ∈ 𝐵 (𝑦 + 𝑧) = 𝑂) | 
| 8 |   | grpinvalem.x | 
. . 3
⊢ ((𝜑 ∧ 𝜓) → 𝑋 ∈ 𝐵) | 
| 9 |   | oveq2 5930 | 
. . . . . 6
⊢ (𝑧 = 𝑋 → (𝑦 + 𝑧) = (𝑦 + 𝑋)) | 
| 10 | 9 | eqeq1d 2205 | 
. . . . 5
⊢ (𝑧 = 𝑋 → ((𝑦 + 𝑧) = 𝑂 ↔ (𝑦 + 𝑋) = 𝑂)) | 
| 11 | 10 | rexbidv 2498 | 
. . . 4
⊢ (𝑧 = 𝑋 → (∃𝑦 ∈ 𝐵 (𝑦 + 𝑧) = 𝑂 ↔ ∃𝑦 ∈ 𝐵 (𝑦 + 𝑋) = 𝑂)) | 
| 12 | 11 | rspccva 2867 | 
. . 3
⊢
((∀𝑧 ∈
𝐵 ∃𝑦 ∈ 𝐵 (𝑦 + 𝑧) = 𝑂 ∧ 𝑋 ∈ 𝐵) → ∃𝑦 ∈ 𝐵 (𝑦 + 𝑋) = 𝑂) | 
| 13 | 7, 8, 12 | syl2an2r 595 | 
. 2
⊢ ((𝜑 ∧ 𝜓) → ∃𝑦 ∈ 𝐵 (𝑦 + 𝑋) = 𝑂) | 
| 14 |   | grpinvalem.e | 
. . . . 5
⊢ ((𝜑 ∧ 𝜓) → (𝑋 + 𝑋) = 𝑋) | 
| 15 | 14 | oveq2d 5938 | 
. . . 4
⊢ ((𝜑 ∧ 𝜓) → (𝑦 + (𝑋 + 𝑋)) = (𝑦 + 𝑋)) | 
| 16 | 15 | adantr 276 | 
. . 3
⊢ (((𝜑 ∧ 𝜓) ∧ (𝑦 ∈ 𝐵 ∧ (𝑦 + 𝑋) = 𝑂)) → (𝑦 + (𝑋 + 𝑋)) = (𝑦 + 𝑋)) | 
| 17 |   | simprr 531 | 
. . . . 5
⊢ (((𝜑 ∧ 𝜓) ∧ (𝑦 ∈ 𝐵 ∧ (𝑦 + 𝑋) = 𝑂)) → (𝑦 + 𝑋) = 𝑂) | 
| 18 | 17 | oveq1d 5937 | 
. . . 4
⊢ (((𝜑 ∧ 𝜓) ∧ (𝑦 ∈ 𝐵 ∧ (𝑦 + 𝑋) = 𝑂)) → ((𝑦 + 𝑋) + 𝑋) = (𝑂 + 𝑋)) | 
| 19 |   | grpinva.a | 
. . . . . . 7
⊢ ((𝜑 ∧ (𝑥 ∈ 𝐵 ∧ 𝑦 ∈ 𝐵 ∧ 𝑧 ∈ 𝐵)) → ((𝑥 + 𝑦) + 𝑧) = (𝑥 + (𝑦 + 𝑧))) | 
| 20 | 19 | caovassg 6082 | 
. . . . . 6
⊢ ((𝜑 ∧ (𝑢 ∈ 𝐵 ∧ 𝑣 ∈ 𝐵 ∧ 𝑤 ∈ 𝐵)) → ((𝑢 + 𝑣) + 𝑤) = (𝑢 + (𝑣 + 𝑤))) | 
| 21 | 20 | ad4ant14 514 | 
. . . . 5
⊢ ((((𝜑 ∧ 𝜓) ∧ (𝑦 ∈ 𝐵 ∧ (𝑦 + 𝑋) = 𝑂)) ∧ (𝑢 ∈ 𝐵 ∧ 𝑣 ∈ 𝐵 ∧ 𝑤 ∈ 𝐵)) → ((𝑢 + 𝑣) + 𝑤) = (𝑢 + (𝑣 + 𝑤))) | 
| 22 |   | simprl 529 | 
. . . . 5
⊢ (((𝜑 ∧ 𝜓) ∧ (𝑦 ∈ 𝐵 ∧ (𝑦 + 𝑋) = 𝑂)) → 𝑦 ∈ 𝐵) | 
| 23 | 8 | adantr 276 | 
. . . . 5
⊢ (((𝜑 ∧ 𝜓) ∧ (𝑦 ∈ 𝐵 ∧ (𝑦 + 𝑋) = 𝑂)) → 𝑋 ∈ 𝐵) | 
| 24 | 21, 22, 23, 23 | caovassd 6083 | 
. . . 4
⊢ (((𝜑 ∧ 𝜓) ∧ (𝑦 ∈ 𝐵 ∧ (𝑦 + 𝑋) = 𝑂)) → ((𝑦 + 𝑋) + 𝑋) = (𝑦 + (𝑋 + 𝑋))) | 
| 25 |   | oveq2 5930 | 
. . . . . . 7
⊢ (𝑦 = 𝑋 → (𝑂 + 𝑦) = (𝑂 + 𝑋)) | 
| 26 |   | id 19 | 
. . . . . . 7
⊢ (𝑦 = 𝑋 → 𝑦 = 𝑋) | 
| 27 | 25, 26 | eqeq12d 2211 | 
. . . . . 6
⊢ (𝑦 = 𝑋 → ((𝑂 + 𝑦) = 𝑦 ↔ (𝑂 + 𝑋) = 𝑋)) | 
| 28 |   | grpinva.i | 
. . . . . . . . 9
⊢ ((𝜑 ∧ 𝑥 ∈ 𝐵) → (𝑂 + 𝑥) = 𝑥) | 
| 29 | 28 | ralrimiva 2570 | 
. . . . . . . 8
⊢ (𝜑 → ∀𝑥 ∈ 𝐵 (𝑂 + 𝑥) = 𝑥) | 
| 30 |   | oveq2 5930 | 
. . . . . . . . . 10
⊢ (𝑥 = 𝑦 → (𝑂 + 𝑥) = (𝑂 + 𝑦)) | 
| 31 |   | id 19 | 
. . . . . . . . . 10
⊢ (𝑥 = 𝑦 → 𝑥 = 𝑦) | 
| 32 | 30, 31 | eqeq12d 2211 | 
. . . . . . . . 9
⊢ (𝑥 = 𝑦 → ((𝑂 + 𝑥) = 𝑥 ↔ (𝑂 + 𝑦) = 𝑦)) | 
| 33 | 32 | cbvralvw 2733 | 
. . . . . . . 8
⊢
(∀𝑥 ∈
𝐵 (𝑂 + 𝑥) = 𝑥 ↔ ∀𝑦 ∈ 𝐵 (𝑂 + 𝑦) = 𝑦) | 
| 34 | 29, 33 | sylib 122 | 
. . . . . . 7
⊢ (𝜑 → ∀𝑦 ∈ 𝐵 (𝑂 + 𝑦) = 𝑦) | 
| 35 | 34 | adantr 276 | 
. . . . . 6
⊢ ((𝜑 ∧ 𝜓) → ∀𝑦 ∈ 𝐵 (𝑂 + 𝑦) = 𝑦) | 
| 36 | 27, 35, 8 | rspcdva 2873 | 
. . . . 5
⊢ ((𝜑 ∧ 𝜓) → (𝑂 + 𝑋) = 𝑋) | 
| 37 | 36 | adantr 276 | 
. . . 4
⊢ (((𝜑 ∧ 𝜓) ∧ (𝑦 ∈ 𝐵 ∧ (𝑦 + 𝑋) = 𝑂)) → (𝑂 + 𝑋) = 𝑋) | 
| 38 | 18, 24, 37 | 3eqtr3d 2237 | 
. . 3
⊢ (((𝜑 ∧ 𝜓) ∧ (𝑦 ∈ 𝐵 ∧ (𝑦 + 𝑋) = 𝑂)) → (𝑦 + (𝑋 + 𝑋)) = 𝑋) | 
| 39 | 16, 38, 17 | 3eqtr3d 2237 | 
. 2
⊢ (((𝜑 ∧ 𝜓) ∧ (𝑦 ∈ 𝐵 ∧ (𝑦 + 𝑋) = 𝑂)) → 𝑋 = 𝑂) | 
| 40 | 13, 39 | rexlimddv 2619 | 
1
⊢ ((𝜑 ∧ 𝜓) → 𝑋 = 𝑂) |