Proof of Theorem lmodcom
| Step | Hyp | Ref
 | Expression | 
| 1 |   | simp1 999 | 
. . . . . . . 8
⊢ ((𝑊 ∈ LMod ∧ 𝑋 ∈ 𝑉 ∧ 𝑌 ∈ 𝑉) → 𝑊 ∈ LMod) | 
| 2 |   | eqid 2196 | 
. . . . . . . . . . 11
⊢
(Scalar‘𝑊) =
(Scalar‘𝑊) | 
| 3 |   | eqid 2196 | 
. . . . . . . . . . 11
⊢
(Base‘(Scalar‘𝑊)) = (Base‘(Scalar‘𝑊)) | 
| 4 |   | eqid 2196 | 
. . . . . . . . . . 11
⊢
(1r‘(Scalar‘𝑊)) =
(1r‘(Scalar‘𝑊)) | 
| 5 | 2, 3, 4 | lmod1cl 13871 | 
. . . . . . . . . 10
⊢ (𝑊 ∈ LMod →
(1r‘(Scalar‘𝑊)) ∈ (Base‘(Scalar‘𝑊))) | 
| 6 | 1, 5 | syl 14 | 
. . . . . . . . 9
⊢ ((𝑊 ∈ LMod ∧ 𝑋 ∈ 𝑉 ∧ 𝑌 ∈ 𝑉) →
(1r‘(Scalar‘𝑊)) ∈ (Base‘(Scalar‘𝑊))) | 
| 7 |   | eqid 2196 | 
. . . . . . . . . 10
⊢
(+g‘(Scalar‘𝑊)) =
(+g‘(Scalar‘𝑊)) | 
| 8 | 2, 3, 7 | lmodacl 13855 | 
. . . . . . . . 9
⊢ ((𝑊 ∈ LMod ∧
(1r‘(Scalar‘𝑊)) ∈ (Base‘(Scalar‘𝑊)) ∧
(1r‘(Scalar‘𝑊)) ∈ (Base‘(Scalar‘𝑊))) →
((1r‘(Scalar‘𝑊))(+g‘(Scalar‘𝑊))(1r‘(Scalar‘𝑊))) ∈
(Base‘(Scalar‘𝑊))) | 
| 9 | 1, 6, 6, 8 | syl3anc 1249 | 
. . . . . . . 8
⊢ ((𝑊 ∈ LMod ∧ 𝑋 ∈ 𝑉 ∧ 𝑌 ∈ 𝑉) →
((1r‘(Scalar‘𝑊))(+g‘(Scalar‘𝑊))(1r‘(Scalar‘𝑊))) ∈
(Base‘(Scalar‘𝑊))) | 
| 10 |   | simp2 1000 | 
. . . . . . . 8
⊢ ((𝑊 ∈ LMod ∧ 𝑋 ∈ 𝑉 ∧ 𝑌 ∈ 𝑉) → 𝑋 ∈ 𝑉) | 
| 11 |   | simp3 1001 | 
. . . . . . . 8
⊢ ((𝑊 ∈ LMod ∧ 𝑋 ∈ 𝑉 ∧ 𝑌 ∈ 𝑉) → 𝑌 ∈ 𝑉) | 
| 12 |   | lmodcom.v | 
. . . . . . . . 9
⊢ 𝑉 = (Base‘𝑊) | 
| 13 |   | lmodcom.a | 
. . . . . . . . 9
⊢  + =
(+g‘𝑊) | 
| 14 |   | eqid 2196 | 
. . . . . . . . 9
⊢ (
·𝑠 ‘𝑊) = ( ·𝑠
‘𝑊) | 
| 15 | 12, 13, 2, 14, 3 | lmodvsdi 13867 | 
. . . . . . . 8
⊢ ((𝑊 ∈ LMod ∧
(((1r‘(Scalar‘𝑊))(+g‘(Scalar‘𝑊))(1r‘(Scalar‘𝑊))) ∈
(Base‘(Scalar‘𝑊)) ∧ 𝑋 ∈ 𝑉 ∧ 𝑌 ∈ 𝑉)) →
(((1r‘(Scalar‘𝑊))(+g‘(Scalar‘𝑊))(1r‘(Scalar‘𝑊)))(
·𝑠 ‘𝑊)(𝑋 + 𝑌)) =
((((1r‘(Scalar‘𝑊))(+g‘(Scalar‘𝑊))(1r‘(Scalar‘𝑊)))(
·𝑠 ‘𝑊)𝑋) +
(((1r‘(Scalar‘𝑊))(+g‘(Scalar‘𝑊))(1r‘(Scalar‘𝑊)))(
·𝑠 ‘𝑊)𝑌))) | 
| 16 | 1, 9, 10, 11, 15 | syl13anc 1251 | 
. . . . . . 7
⊢ ((𝑊 ∈ LMod ∧ 𝑋 ∈ 𝑉 ∧ 𝑌 ∈ 𝑉) →
(((1r‘(Scalar‘𝑊))(+g‘(Scalar‘𝑊))(1r‘(Scalar‘𝑊)))(
·𝑠 ‘𝑊)(𝑋 + 𝑌)) =
((((1r‘(Scalar‘𝑊))(+g‘(Scalar‘𝑊))(1r‘(Scalar‘𝑊)))(
·𝑠 ‘𝑊)𝑋) +
(((1r‘(Scalar‘𝑊))(+g‘(Scalar‘𝑊))(1r‘(Scalar‘𝑊)))(
·𝑠 ‘𝑊)𝑌))) | 
| 17 | 12, 13 | lmodvacl 13858 | 
. . . . . . . 8
⊢ ((𝑊 ∈ LMod ∧ 𝑋 ∈ 𝑉 ∧ 𝑌 ∈ 𝑉) → (𝑋 + 𝑌) ∈ 𝑉) | 
| 18 | 12, 13, 2, 14, 3, 7 | lmodvsdir 13868 | 
. . . . . . . 8
⊢ ((𝑊 ∈ LMod ∧
((1r‘(Scalar‘𝑊)) ∈ (Base‘(Scalar‘𝑊)) ∧
(1r‘(Scalar‘𝑊)) ∈ (Base‘(Scalar‘𝑊)) ∧ (𝑋 + 𝑌) ∈ 𝑉)) →
(((1r‘(Scalar‘𝑊))(+g‘(Scalar‘𝑊))(1r‘(Scalar‘𝑊)))(
·𝑠 ‘𝑊)(𝑋 + 𝑌)) =
(((1r‘(Scalar‘𝑊))( ·𝑠
‘𝑊)(𝑋 + 𝑌)) +
((1r‘(Scalar‘𝑊))( ·𝑠
‘𝑊)(𝑋 + 𝑌)))) | 
| 19 | 1, 6, 6, 17, 18 | syl13anc 1251 | 
. . . . . . 7
⊢ ((𝑊 ∈ LMod ∧ 𝑋 ∈ 𝑉 ∧ 𝑌 ∈ 𝑉) →
(((1r‘(Scalar‘𝑊))(+g‘(Scalar‘𝑊))(1r‘(Scalar‘𝑊)))(
·𝑠 ‘𝑊)(𝑋 + 𝑌)) =
(((1r‘(Scalar‘𝑊))( ·𝑠
‘𝑊)(𝑋 + 𝑌)) +
((1r‘(Scalar‘𝑊))( ·𝑠
‘𝑊)(𝑋 + 𝑌)))) | 
| 20 | 16, 19 | eqtr3d 2231 | 
. . . . . 6
⊢ ((𝑊 ∈ LMod ∧ 𝑋 ∈ 𝑉 ∧ 𝑌 ∈ 𝑉) →
((((1r‘(Scalar‘𝑊))(+g‘(Scalar‘𝑊))(1r‘(Scalar‘𝑊)))(
·𝑠 ‘𝑊)𝑋) +
(((1r‘(Scalar‘𝑊))(+g‘(Scalar‘𝑊))(1r‘(Scalar‘𝑊)))(
·𝑠 ‘𝑊)𝑌)) =
(((1r‘(Scalar‘𝑊))( ·𝑠
‘𝑊)(𝑋 + 𝑌)) +
((1r‘(Scalar‘𝑊))( ·𝑠
‘𝑊)(𝑋 + 𝑌)))) | 
| 21 | 12, 13, 2, 14, 3, 7 | lmodvsdir 13868 | 
. . . . . . . . 9
⊢ ((𝑊 ∈ LMod ∧
((1r‘(Scalar‘𝑊)) ∈ (Base‘(Scalar‘𝑊)) ∧
(1r‘(Scalar‘𝑊)) ∈ (Base‘(Scalar‘𝑊)) ∧ 𝑋 ∈ 𝑉)) →
(((1r‘(Scalar‘𝑊))(+g‘(Scalar‘𝑊))(1r‘(Scalar‘𝑊)))(
·𝑠 ‘𝑊)𝑋) =
(((1r‘(Scalar‘𝑊))( ·𝑠
‘𝑊)𝑋) +
((1r‘(Scalar‘𝑊))( ·𝑠
‘𝑊)𝑋))) | 
| 22 | 1, 6, 6, 10, 21 | syl13anc 1251 | 
. . . . . . . 8
⊢ ((𝑊 ∈ LMod ∧ 𝑋 ∈ 𝑉 ∧ 𝑌 ∈ 𝑉) →
(((1r‘(Scalar‘𝑊))(+g‘(Scalar‘𝑊))(1r‘(Scalar‘𝑊)))(
·𝑠 ‘𝑊)𝑋) =
(((1r‘(Scalar‘𝑊))( ·𝑠
‘𝑊)𝑋) +
((1r‘(Scalar‘𝑊))( ·𝑠
‘𝑊)𝑋))) | 
| 23 | 12, 2, 14, 4 | lmodvs1 13872 | 
. . . . . . . . . 10
⊢ ((𝑊 ∈ LMod ∧ 𝑋 ∈ 𝑉) →
((1r‘(Scalar‘𝑊))( ·𝑠
‘𝑊)𝑋) = 𝑋) | 
| 24 | 1, 10, 23 | syl2anc 411 | 
. . . . . . . . 9
⊢ ((𝑊 ∈ LMod ∧ 𝑋 ∈ 𝑉 ∧ 𝑌 ∈ 𝑉) →
((1r‘(Scalar‘𝑊))( ·𝑠
‘𝑊)𝑋) = 𝑋) | 
| 25 | 24, 24 | oveq12d 5940 | 
. . . . . . . 8
⊢ ((𝑊 ∈ LMod ∧ 𝑋 ∈ 𝑉 ∧ 𝑌 ∈ 𝑉) →
(((1r‘(Scalar‘𝑊))( ·𝑠
‘𝑊)𝑋) +
((1r‘(Scalar‘𝑊))( ·𝑠
‘𝑊)𝑋)) = (𝑋 + 𝑋)) | 
| 26 | 22, 25 | eqtrd 2229 | 
. . . . . . 7
⊢ ((𝑊 ∈ LMod ∧ 𝑋 ∈ 𝑉 ∧ 𝑌 ∈ 𝑉) →
(((1r‘(Scalar‘𝑊))(+g‘(Scalar‘𝑊))(1r‘(Scalar‘𝑊)))(
·𝑠 ‘𝑊)𝑋) = (𝑋 + 𝑋)) | 
| 27 | 12, 13, 2, 14, 3, 7 | lmodvsdir 13868 | 
. . . . . . . . 9
⊢ ((𝑊 ∈ LMod ∧
((1r‘(Scalar‘𝑊)) ∈ (Base‘(Scalar‘𝑊)) ∧
(1r‘(Scalar‘𝑊)) ∈ (Base‘(Scalar‘𝑊)) ∧ 𝑌 ∈ 𝑉)) →
(((1r‘(Scalar‘𝑊))(+g‘(Scalar‘𝑊))(1r‘(Scalar‘𝑊)))(
·𝑠 ‘𝑊)𝑌) =
(((1r‘(Scalar‘𝑊))( ·𝑠
‘𝑊)𝑌) +
((1r‘(Scalar‘𝑊))( ·𝑠
‘𝑊)𝑌))) | 
| 28 | 1, 6, 6, 11, 27 | syl13anc 1251 | 
. . . . . . . 8
⊢ ((𝑊 ∈ LMod ∧ 𝑋 ∈ 𝑉 ∧ 𝑌 ∈ 𝑉) →
(((1r‘(Scalar‘𝑊))(+g‘(Scalar‘𝑊))(1r‘(Scalar‘𝑊)))(
·𝑠 ‘𝑊)𝑌) =
(((1r‘(Scalar‘𝑊))( ·𝑠
‘𝑊)𝑌) +
((1r‘(Scalar‘𝑊))( ·𝑠
‘𝑊)𝑌))) | 
| 29 | 12, 2, 14, 4 | lmodvs1 13872 | 
. . . . . . . . . 10
⊢ ((𝑊 ∈ LMod ∧ 𝑌 ∈ 𝑉) →
((1r‘(Scalar‘𝑊))( ·𝑠
‘𝑊)𝑌) = 𝑌) | 
| 30 | 1, 11, 29 | syl2anc 411 | 
. . . . . . . . 9
⊢ ((𝑊 ∈ LMod ∧ 𝑋 ∈ 𝑉 ∧ 𝑌 ∈ 𝑉) →
((1r‘(Scalar‘𝑊))( ·𝑠
‘𝑊)𝑌) = 𝑌) | 
| 31 | 30, 30 | oveq12d 5940 | 
. . . . . . . 8
⊢ ((𝑊 ∈ LMod ∧ 𝑋 ∈ 𝑉 ∧ 𝑌 ∈ 𝑉) →
(((1r‘(Scalar‘𝑊))( ·𝑠
‘𝑊)𝑌) +
((1r‘(Scalar‘𝑊))( ·𝑠
‘𝑊)𝑌)) = (𝑌 + 𝑌)) | 
| 32 | 28, 31 | eqtrd 2229 | 
. . . . . . 7
⊢ ((𝑊 ∈ LMod ∧ 𝑋 ∈ 𝑉 ∧ 𝑌 ∈ 𝑉) →
(((1r‘(Scalar‘𝑊))(+g‘(Scalar‘𝑊))(1r‘(Scalar‘𝑊)))(
·𝑠 ‘𝑊)𝑌) = (𝑌 + 𝑌)) | 
| 33 | 26, 32 | oveq12d 5940 | 
. . . . . 6
⊢ ((𝑊 ∈ LMod ∧ 𝑋 ∈ 𝑉 ∧ 𝑌 ∈ 𝑉) →
((((1r‘(Scalar‘𝑊))(+g‘(Scalar‘𝑊))(1r‘(Scalar‘𝑊)))(
·𝑠 ‘𝑊)𝑋) +
(((1r‘(Scalar‘𝑊))(+g‘(Scalar‘𝑊))(1r‘(Scalar‘𝑊)))(
·𝑠 ‘𝑊)𝑌)) = ((𝑋 + 𝑋) + (𝑌 + 𝑌))) | 
| 34 | 12, 2, 14, 4 | lmodvs1 13872 | 
. . . . . . . 8
⊢ ((𝑊 ∈ LMod ∧ (𝑋 + 𝑌) ∈ 𝑉) →
((1r‘(Scalar‘𝑊))( ·𝑠
‘𝑊)(𝑋 + 𝑌)) = (𝑋 + 𝑌)) | 
| 35 | 1, 17, 34 | syl2anc 411 | 
. . . . . . 7
⊢ ((𝑊 ∈ LMod ∧ 𝑋 ∈ 𝑉 ∧ 𝑌 ∈ 𝑉) →
((1r‘(Scalar‘𝑊))( ·𝑠
‘𝑊)(𝑋 + 𝑌)) = (𝑋 + 𝑌)) | 
| 36 | 35, 35 | oveq12d 5940 | 
. . . . . 6
⊢ ((𝑊 ∈ LMod ∧ 𝑋 ∈ 𝑉 ∧ 𝑌 ∈ 𝑉) →
(((1r‘(Scalar‘𝑊))( ·𝑠
‘𝑊)(𝑋 + 𝑌)) +
((1r‘(Scalar‘𝑊))( ·𝑠
‘𝑊)(𝑋 + 𝑌))) = ((𝑋 + 𝑌) + (𝑋 + 𝑌))) | 
| 37 | 20, 33, 36 | 3eqtr3d 2237 | 
. . . . 5
⊢ ((𝑊 ∈ LMod ∧ 𝑋 ∈ 𝑉 ∧ 𝑌 ∈ 𝑉) → ((𝑋 + 𝑋) + (𝑌 + 𝑌)) = ((𝑋 + 𝑌) + (𝑋 + 𝑌))) | 
| 38 | 12, 13 | lmodvacl 13858 | 
. . . . . . 7
⊢ ((𝑊 ∈ LMod ∧ 𝑋 ∈ 𝑉 ∧ 𝑋 ∈ 𝑉) → (𝑋 + 𝑋) ∈ 𝑉) | 
| 39 | 1, 10, 10, 38 | syl3anc 1249 | 
. . . . . 6
⊢ ((𝑊 ∈ LMod ∧ 𝑋 ∈ 𝑉 ∧ 𝑌 ∈ 𝑉) → (𝑋 + 𝑋) ∈ 𝑉) | 
| 40 | 12, 13 | lmodass 13859 | 
. . . . . 6
⊢ ((𝑊 ∈ LMod ∧ ((𝑋 + 𝑋) ∈ 𝑉 ∧ 𝑌 ∈ 𝑉 ∧ 𝑌 ∈ 𝑉)) → (((𝑋 + 𝑋) + 𝑌) + 𝑌) = ((𝑋 + 𝑋) + (𝑌 + 𝑌))) | 
| 41 | 1, 39, 11, 11, 40 | syl13anc 1251 | 
. . . . 5
⊢ ((𝑊 ∈ LMod ∧ 𝑋 ∈ 𝑉 ∧ 𝑌 ∈ 𝑉) → (((𝑋 + 𝑋) + 𝑌) + 𝑌) = ((𝑋 + 𝑋) + (𝑌 + 𝑌))) | 
| 42 | 12, 13 | lmodass 13859 | 
. . . . . 6
⊢ ((𝑊 ∈ LMod ∧ ((𝑋 + 𝑌) ∈ 𝑉 ∧ 𝑋 ∈ 𝑉 ∧ 𝑌 ∈ 𝑉)) → (((𝑋 + 𝑌) + 𝑋) + 𝑌) = ((𝑋 + 𝑌) + (𝑋 + 𝑌))) | 
| 43 | 1, 17, 10, 11, 42 | syl13anc 1251 | 
. . . . 5
⊢ ((𝑊 ∈ LMod ∧ 𝑋 ∈ 𝑉 ∧ 𝑌 ∈ 𝑉) → (((𝑋 + 𝑌) + 𝑋) + 𝑌) = ((𝑋 + 𝑌) + (𝑋 + 𝑌))) | 
| 44 | 37, 41, 43 | 3eqtr4d 2239 | 
. . . 4
⊢ ((𝑊 ∈ LMod ∧ 𝑋 ∈ 𝑉 ∧ 𝑌 ∈ 𝑉) → (((𝑋 + 𝑋) + 𝑌) + 𝑌) = (((𝑋 + 𝑌) + 𝑋) + 𝑌)) | 
| 45 |   | lmodgrp 13850 | 
. . . . . 6
⊢ (𝑊 ∈ LMod → 𝑊 ∈ Grp) | 
| 46 | 1, 45 | syl 14 | 
. . . . 5
⊢ ((𝑊 ∈ LMod ∧ 𝑋 ∈ 𝑉 ∧ 𝑌 ∈ 𝑉) → 𝑊 ∈ Grp) | 
| 47 | 12, 13 | lmodvacl 13858 | 
. . . . . 6
⊢ ((𝑊 ∈ LMod ∧ (𝑋 + 𝑋) ∈ 𝑉 ∧ 𝑌 ∈ 𝑉) → ((𝑋 + 𝑋) + 𝑌) ∈ 𝑉) | 
| 48 | 1, 39, 11, 47 | syl3anc 1249 | 
. . . . 5
⊢ ((𝑊 ∈ LMod ∧ 𝑋 ∈ 𝑉 ∧ 𝑌 ∈ 𝑉) → ((𝑋 + 𝑋) + 𝑌) ∈ 𝑉) | 
| 49 | 12, 13 | lmodvacl 13858 | 
. . . . . 6
⊢ ((𝑊 ∈ LMod ∧ (𝑋 + 𝑌) ∈ 𝑉 ∧ 𝑋 ∈ 𝑉) → ((𝑋 + 𝑌) + 𝑋) ∈ 𝑉) | 
| 50 | 1, 17, 10, 49 | syl3anc 1249 | 
. . . . 5
⊢ ((𝑊 ∈ LMod ∧ 𝑋 ∈ 𝑉 ∧ 𝑌 ∈ 𝑉) → ((𝑋 + 𝑌) + 𝑋) ∈ 𝑉) | 
| 51 | 12, 13 | grprcan 13169 | 
. . . . 5
⊢ ((𝑊 ∈ Grp ∧ (((𝑋 + 𝑋) + 𝑌) ∈ 𝑉 ∧ ((𝑋 + 𝑌) + 𝑋) ∈ 𝑉 ∧ 𝑌 ∈ 𝑉)) → ((((𝑋 + 𝑋) + 𝑌) + 𝑌) = (((𝑋 + 𝑌) + 𝑋) + 𝑌) ↔ ((𝑋 + 𝑋) + 𝑌) = ((𝑋 + 𝑌) + 𝑋))) | 
| 52 | 46, 48, 50, 11, 51 | syl13anc 1251 | 
. . . 4
⊢ ((𝑊 ∈ LMod ∧ 𝑋 ∈ 𝑉 ∧ 𝑌 ∈ 𝑉) → ((((𝑋 + 𝑋) + 𝑌) + 𝑌) = (((𝑋 + 𝑌) + 𝑋) + 𝑌) ↔ ((𝑋 + 𝑋) + 𝑌) = ((𝑋 + 𝑌) + 𝑋))) | 
| 53 | 44, 52 | mpbid 147 | 
. . 3
⊢ ((𝑊 ∈ LMod ∧ 𝑋 ∈ 𝑉 ∧ 𝑌 ∈ 𝑉) → ((𝑋 + 𝑋) + 𝑌) = ((𝑋 + 𝑌) + 𝑋)) | 
| 54 | 12, 13 | lmodass 13859 | 
. . . 4
⊢ ((𝑊 ∈ LMod ∧ (𝑋 ∈ 𝑉 ∧ 𝑋 ∈ 𝑉 ∧ 𝑌 ∈ 𝑉)) → ((𝑋 + 𝑋) + 𝑌) = (𝑋 + (𝑋 + 𝑌))) | 
| 55 | 1, 10, 10, 11, 54 | syl13anc 1251 | 
. . 3
⊢ ((𝑊 ∈ LMod ∧ 𝑋 ∈ 𝑉 ∧ 𝑌 ∈ 𝑉) → ((𝑋 + 𝑋) + 𝑌) = (𝑋 + (𝑋 + 𝑌))) | 
| 56 | 12, 13 | lmodass 13859 | 
. . . 4
⊢ ((𝑊 ∈ LMod ∧ (𝑋 ∈ 𝑉 ∧ 𝑌 ∈ 𝑉 ∧ 𝑋 ∈ 𝑉)) → ((𝑋 + 𝑌) + 𝑋) = (𝑋 + (𝑌 + 𝑋))) | 
| 57 | 1, 10, 11, 10, 56 | syl13anc 1251 | 
. . 3
⊢ ((𝑊 ∈ LMod ∧ 𝑋 ∈ 𝑉 ∧ 𝑌 ∈ 𝑉) → ((𝑋 + 𝑌) + 𝑋) = (𝑋 + (𝑌 + 𝑋))) | 
| 58 | 53, 55, 57 | 3eqtr3d 2237 | 
. 2
⊢ ((𝑊 ∈ LMod ∧ 𝑋 ∈ 𝑉 ∧ 𝑌 ∈ 𝑉) → (𝑋 + (𝑋 + 𝑌)) = (𝑋 + (𝑌 + 𝑋))) | 
| 59 | 12, 13 | lmodvacl 13858 | 
. . . 4
⊢ ((𝑊 ∈ LMod ∧ 𝑌 ∈ 𝑉 ∧ 𝑋 ∈ 𝑉) → (𝑌 + 𝑋) ∈ 𝑉) | 
| 60 | 59 | 3com23 1211 | 
. . 3
⊢ ((𝑊 ∈ LMod ∧ 𝑋 ∈ 𝑉 ∧ 𝑌 ∈ 𝑉) → (𝑌 + 𝑋) ∈ 𝑉) | 
| 61 | 12, 13 | lmodlcan 13860 | 
. . 3
⊢ ((𝑊 ∈ LMod ∧ ((𝑋 + 𝑌) ∈ 𝑉 ∧ (𝑌 + 𝑋) ∈ 𝑉 ∧ 𝑋 ∈ 𝑉)) → ((𝑋 + (𝑋 + 𝑌)) = (𝑋 + (𝑌 + 𝑋)) ↔ (𝑋 + 𝑌) = (𝑌 + 𝑋))) | 
| 62 | 1, 17, 60, 10, 61 | syl13anc 1251 | 
. 2
⊢ ((𝑊 ∈ LMod ∧ 𝑋 ∈ 𝑉 ∧ 𝑌 ∈ 𝑉) → ((𝑋 + (𝑋 + 𝑌)) = (𝑋 + (𝑌 + 𝑋)) ↔ (𝑋 + 𝑌) = (𝑌 + 𝑋))) | 
| 63 | 58, 62 | mpbid 147 | 
1
⊢ ((𝑊 ∈ LMod ∧ 𝑋 ∈ 𝑉 ∧ 𝑌 ∈ 𝑉) → (𝑋 + 𝑌) = (𝑌 + 𝑋)) |