Step |
Hyp |
Ref |
Expression |
1 |
|
cringm4.1 |
⊢ 𝐵 = ( Base ‘ 𝑅 ) |
2 |
|
cringm4.2 |
⊢ · = ( .r ‘ 𝑅 ) |
3 |
|
eqid |
⊢ ( mulGrp ‘ 𝑅 ) = ( mulGrp ‘ 𝑅 ) |
4 |
3
|
crngmgp |
⊢ ( 𝑅 ∈ CRing → ( mulGrp ‘ 𝑅 ) ∈ CMnd ) |
5 |
3 1
|
mgpbas |
⊢ 𝐵 = ( Base ‘ ( mulGrp ‘ 𝑅 ) ) |
6 |
3 2
|
mgpplusg |
⊢ · = ( +g ‘ ( mulGrp ‘ 𝑅 ) ) |
7 |
5 6
|
cmn4 |
⊢ ( ( ( mulGrp ‘ 𝑅 ) ∈ CMnd ∧ ( 𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵 ) ∧ ( 𝑍 ∈ 𝐵 ∧ 𝑊 ∈ 𝐵 ) ) → ( ( 𝑋 · 𝑌 ) · ( 𝑍 · 𝑊 ) ) = ( ( 𝑋 · 𝑍 ) · ( 𝑌 · 𝑊 ) ) ) |
8 |
4 7
|
syl3an1 |
⊢ ( ( 𝑅 ∈ CRing ∧ ( 𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵 ) ∧ ( 𝑍 ∈ 𝐵 ∧ 𝑊 ∈ 𝐵 ) ) → ( ( 𝑋 · 𝑌 ) · ( 𝑍 · 𝑊 ) ) = ( ( 𝑋 · 𝑍 ) · ( 𝑌 · 𝑊 ) ) ) |