Proof of Theorem grpinvadd
| Step | Hyp | Ref | Expression | 
|---|
| 1 |  | simp1 1136 | . . . 4
⊢ ((𝐺 ∈ Grp ∧ 𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵) → 𝐺 ∈ Grp) | 
| 2 |  | simp2 1137 | . . . 4
⊢ ((𝐺 ∈ Grp ∧ 𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵) → 𝑋 ∈ 𝐵) | 
| 3 |  | simp3 1138 | . . . 4
⊢ ((𝐺 ∈ Grp ∧ 𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵) → 𝑌 ∈ 𝐵) | 
| 4 |  | grpinvadd.b | . . . . . . 7
⊢ 𝐵 = (Base‘𝐺) | 
| 5 |  | grpinvadd.n | . . . . . . 7
⊢ 𝑁 = (invg‘𝐺) | 
| 6 | 4, 5 | grpinvcl 19006 | . . . . . 6
⊢ ((𝐺 ∈ Grp ∧ 𝑌 ∈ 𝐵) → (𝑁‘𝑌) ∈ 𝐵) | 
| 7 | 6 | 3adant2 1131 | . . . . 5
⊢ ((𝐺 ∈ Grp ∧ 𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵) → (𝑁‘𝑌) ∈ 𝐵) | 
| 8 | 4, 5 | grpinvcl 19006 | . . . . . 6
⊢ ((𝐺 ∈ Grp ∧ 𝑋 ∈ 𝐵) → (𝑁‘𝑋) ∈ 𝐵) | 
| 9 | 8 | 3adant3 1132 | . . . . 5
⊢ ((𝐺 ∈ Grp ∧ 𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵) → (𝑁‘𝑋) ∈ 𝐵) | 
| 10 |  | grpinvadd.p | . . . . . 6
⊢  + =
(+g‘𝐺) | 
| 11 | 4, 10 | grpcl 18960 | . . . . 5
⊢ ((𝐺 ∈ Grp ∧ (𝑁‘𝑌) ∈ 𝐵 ∧ (𝑁‘𝑋) ∈ 𝐵) → ((𝑁‘𝑌) + (𝑁‘𝑋)) ∈ 𝐵) | 
| 12 | 1, 7, 9, 11 | syl3anc 1372 | . . . 4
⊢ ((𝐺 ∈ Grp ∧ 𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵) → ((𝑁‘𝑌) + (𝑁‘𝑋)) ∈ 𝐵) | 
| 13 | 4, 10 | grpass 18961 | . . . 4
⊢ ((𝐺 ∈ Grp ∧ (𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵 ∧ ((𝑁‘𝑌) + (𝑁‘𝑋)) ∈ 𝐵)) → ((𝑋 + 𝑌) + ((𝑁‘𝑌) + (𝑁‘𝑋))) = (𝑋 + (𝑌 + ((𝑁‘𝑌) + (𝑁‘𝑋))))) | 
| 14 | 1, 2, 3, 12, 13 | syl13anc 1373 | . . 3
⊢ ((𝐺 ∈ Grp ∧ 𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵) → ((𝑋 + 𝑌) + ((𝑁‘𝑌) + (𝑁‘𝑋))) = (𝑋 + (𝑌 + ((𝑁‘𝑌) + (𝑁‘𝑋))))) | 
| 15 |  | eqid 2736 | . . . . . . . 8
⊢
(0g‘𝐺) = (0g‘𝐺) | 
| 16 | 4, 10, 15, 5 | grprinv 19009 | . . . . . . 7
⊢ ((𝐺 ∈ Grp ∧ 𝑌 ∈ 𝐵) → (𝑌 + (𝑁‘𝑌)) = (0g‘𝐺)) | 
| 17 | 16 | 3adant2 1131 | . . . . . 6
⊢ ((𝐺 ∈ Grp ∧ 𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵) → (𝑌 + (𝑁‘𝑌)) = (0g‘𝐺)) | 
| 18 | 17 | oveq1d 7447 | . . . . 5
⊢ ((𝐺 ∈ Grp ∧ 𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵) → ((𝑌 + (𝑁‘𝑌)) + (𝑁‘𝑋)) = ((0g‘𝐺) + (𝑁‘𝑋))) | 
| 19 | 4, 10 | grpass 18961 | . . . . . 6
⊢ ((𝐺 ∈ Grp ∧ (𝑌 ∈ 𝐵 ∧ (𝑁‘𝑌) ∈ 𝐵 ∧ (𝑁‘𝑋) ∈ 𝐵)) → ((𝑌 + (𝑁‘𝑌)) + (𝑁‘𝑋)) = (𝑌 + ((𝑁‘𝑌) + (𝑁‘𝑋)))) | 
| 20 | 1, 3, 7, 9, 19 | syl13anc 1373 | . . . . 5
⊢ ((𝐺 ∈ Grp ∧ 𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵) → ((𝑌 + (𝑁‘𝑌)) + (𝑁‘𝑋)) = (𝑌 + ((𝑁‘𝑌) + (𝑁‘𝑋)))) | 
| 21 | 4, 10, 15 | grplid 18986 | . . . . . 6
⊢ ((𝐺 ∈ Grp ∧ (𝑁‘𝑋) ∈ 𝐵) → ((0g‘𝐺) + (𝑁‘𝑋)) = (𝑁‘𝑋)) | 
| 22 | 1, 9, 21 | syl2anc 584 | . . . . 5
⊢ ((𝐺 ∈ Grp ∧ 𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵) → ((0g‘𝐺) + (𝑁‘𝑋)) = (𝑁‘𝑋)) | 
| 23 | 18, 20, 22 | 3eqtr3d 2784 | . . . 4
⊢ ((𝐺 ∈ Grp ∧ 𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵) → (𝑌 + ((𝑁‘𝑌) + (𝑁‘𝑋))) = (𝑁‘𝑋)) | 
| 24 | 23 | oveq2d 7448 | . . 3
⊢ ((𝐺 ∈ Grp ∧ 𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵) → (𝑋 + (𝑌 + ((𝑁‘𝑌) + (𝑁‘𝑋)))) = (𝑋 + (𝑁‘𝑋))) | 
| 25 | 4, 10, 15, 5 | grprinv 19009 | . . . 4
⊢ ((𝐺 ∈ Grp ∧ 𝑋 ∈ 𝐵) → (𝑋 + (𝑁‘𝑋)) = (0g‘𝐺)) | 
| 26 | 25 | 3adant3 1132 | . . 3
⊢ ((𝐺 ∈ Grp ∧ 𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵) → (𝑋 + (𝑁‘𝑋)) = (0g‘𝐺)) | 
| 27 | 14, 24, 26 | 3eqtrd 2780 | . 2
⊢ ((𝐺 ∈ Grp ∧ 𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵) → ((𝑋 + 𝑌) + ((𝑁‘𝑌) + (𝑁‘𝑋))) = (0g‘𝐺)) | 
| 28 | 4, 10 | grpcl 18960 | . . 3
⊢ ((𝐺 ∈ Grp ∧ 𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵) → (𝑋 + 𝑌) ∈ 𝐵) | 
| 29 | 4, 10, 15, 5 | grpinvid1 19010 | . . 3
⊢ ((𝐺 ∈ Grp ∧ (𝑋 + 𝑌) ∈ 𝐵 ∧ ((𝑁‘𝑌) + (𝑁‘𝑋)) ∈ 𝐵) → ((𝑁‘(𝑋 + 𝑌)) = ((𝑁‘𝑌) + (𝑁‘𝑋)) ↔ ((𝑋 + 𝑌) + ((𝑁‘𝑌) + (𝑁‘𝑋))) = (0g‘𝐺))) | 
| 30 | 1, 28, 12, 29 | syl3anc 1372 | . 2
⊢ ((𝐺 ∈ Grp ∧ 𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵) → ((𝑁‘(𝑋 + 𝑌)) = ((𝑁‘𝑌) + (𝑁‘𝑋)) ↔ ((𝑋 + 𝑌) + ((𝑁‘𝑌) + (𝑁‘𝑋))) = (0g‘𝐺))) | 
| 31 | 27, 30 | mpbird 257 | 1
⊢ ((𝐺 ∈ Grp ∧ 𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵) → (𝑁‘(𝑋 + 𝑌)) = ((𝑁‘𝑌) + (𝑁‘𝑋))) |