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Description: Commutativity of the additive group of a ring. (See also lmodcom .) This proof requires the existence of a multiplicative identity, and the existence of additive inverses. Therefore, this proof is not applicable for semirings. (Contributed by Gérard Lang, 4-Dec-2014) (Proof shortened by AV, 1-Feb-2025)
| Ref | Expression | ||
|---|---|---|---|
| Hypotheses | ringacl.b | ⊢ 𝐵 = ( Base ‘ 𝑅 ) | |
| ringacl.p | ⊢ + = ( +g ‘ 𝑅 ) | ||
| Assertion | ringcom | ⊢ ( ( 𝑅 ∈ Ring ∧ 𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵 ) → ( 𝑋 + 𝑌 ) = ( 𝑌 + 𝑋 ) ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | ringacl.b | ⊢ 𝐵 = ( Base ‘ 𝑅 ) | |
| 2 | ringacl.p | ⊢ + = ( +g ‘ 𝑅 ) | |
| 3 | 1 2 | ringcomlem | ⊢ ( ( 𝑅 ∈ Ring ∧ 𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵 ) → ( ( 𝑋 + 𝑋 ) + ( 𝑌 + 𝑌 ) ) = ( ( 𝑋 + 𝑌 ) + ( 𝑋 + 𝑌 ) ) ) |
| 4 | simp1 | ⊢ ( ( 𝑅 ∈ Ring ∧ 𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵 ) → 𝑅 ∈ Ring ) | |
| 5 | 4 | ringgrpd | ⊢ ( ( 𝑅 ∈ Ring ∧ 𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵 ) → 𝑅 ∈ Grp ) |
| 6 | simp2 | ⊢ ( ( 𝑅 ∈ Ring ∧ 𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵 ) → 𝑋 ∈ 𝐵 ) | |
| 7 | 1 2 | ringacl | ⊢ ( ( 𝑅 ∈ Ring ∧ 𝑋 ∈ 𝐵 ∧ 𝑋 ∈ 𝐵 ) → ( 𝑋 + 𝑋 ) ∈ 𝐵 ) |
| 8 | 4 6 6 7 | syl3anc | ⊢ ( ( 𝑅 ∈ Ring ∧ 𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵 ) → ( 𝑋 + 𝑋 ) ∈ 𝐵 ) |
| 9 | simp3 | ⊢ ( ( 𝑅 ∈ Ring ∧ 𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵 ) → 𝑌 ∈ 𝐵 ) | |
| 10 | 1 2 | grpass | ⊢ ( ( 𝑅 ∈ Grp ∧ ( ( 𝑋 + 𝑋 ) ∈ 𝐵 ∧ 𝑌 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵 ) ) → ( ( ( 𝑋 + 𝑋 ) + 𝑌 ) + 𝑌 ) = ( ( 𝑋 + 𝑋 ) + ( 𝑌 + 𝑌 ) ) ) |
| 11 | 5 8 9 9 10 | syl13anc | ⊢ ( ( 𝑅 ∈ Ring ∧ 𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵 ) → ( ( ( 𝑋 + 𝑋 ) + 𝑌 ) + 𝑌 ) = ( ( 𝑋 + 𝑋 ) + ( 𝑌 + 𝑌 ) ) ) |
| 12 | 1 2 | ringacl | ⊢ ( ( 𝑅 ∈ Ring ∧ 𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵 ) → ( 𝑋 + 𝑌 ) ∈ 𝐵 ) |
| 13 | 1 2 | grpass | ⊢ ( ( 𝑅 ∈ Grp ∧ ( ( 𝑋 + 𝑌 ) ∈ 𝐵 ∧ 𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵 ) ) → ( ( ( 𝑋 + 𝑌 ) + 𝑋 ) + 𝑌 ) = ( ( 𝑋 + 𝑌 ) + ( 𝑋 + 𝑌 ) ) ) |
| 14 | 5 12 6 9 13 | syl13anc | ⊢ ( ( 𝑅 ∈ Ring ∧ 𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵 ) → ( ( ( 𝑋 + 𝑌 ) + 𝑋 ) + 𝑌 ) = ( ( 𝑋 + 𝑌 ) + ( 𝑋 + 𝑌 ) ) ) |
| 15 | 3 11 14 | 3eqtr4d | ⊢ ( ( 𝑅 ∈ Ring ∧ 𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵 ) → ( ( ( 𝑋 + 𝑋 ) + 𝑌 ) + 𝑌 ) = ( ( ( 𝑋 + 𝑌 ) + 𝑋 ) + 𝑌 ) ) |
| 16 | 1 2 | ringacl | ⊢ ( ( 𝑅 ∈ Ring ∧ ( 𝑋 + 𝑋 ) ∈ 𝐵 ∧ 𝑌 ∈ 𝐵 ) → ( ( 𝑋 + 𝑋 ) + 𝑌 ) ∈ 𝐵 ) |
| 17 | 4 8 9 16 | syl3anc | ⊢ ( ( 𝑅 ∈ Ring ∧ 𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵 ) → ( ( 𝑋 + 𝑋 ) + 𝑌 ) ∈ 𝐵 ) |
| 18 | 1 2 | ringacl | ⊢ ( ( 𝑅 ∈ Ring ∧ ( 𝑋 + 𝑌 ) ∈ 𝐵 ∧ 𝑋 ∈ 𝐵 ) → ( ( 𝑋 + 𝑌 ) + 𝑋 ) ∈ 𝐵 ) |
| 19 | 4 12 6 18 | syl3anc | ⊢ ( ( 𝑅 ∈ Ring ∧ 𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵 ) → ( ( 𝑋 + 𝑌 ) + 𝑋 ) ∈ 𝐵 ) |
| 20 | 1 2 | grprcan | ⊢ ( ( 𝑅 ∈ Grp ∧ ( ( ( 𝑋 + 𝑋 ) + 𝑌 ) ∈ 𝐵 ∧ ( ( 𝑋 + 𝑌 ) + 𝑋 ) ∈ 𝐵 ∧ 𝑌 ∈ 𝐵 ) ) → ( ( ( ( 𝑋 + 𝑋 ) + 𝑌 ) + 𝑌 ) = ( ( ( 𝑋 + 𝑌 ) + 𝑋 ) + 𝑌 ) ↔ ( ( 𝑋 + 𝑋 ) + 𝑌 ) = ( ( 𝑋 + 𝑌 ) + 𝑋 ) ) ) |
| 21 | 5 17 19 9 20 | syl13anc | ⊢ ( ( 𝑅 ∈ Ring ∧ 𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵 ) → ( ( ( ( 𝑋 + 𝑋 ) + 𝑌 ) + 𝑌 ) = ( ( ( 𝑋 + 𝑌 ) + 𝑋 ) + 𝑌 ) ↔ ( ( 𝑋 + 𝑋 ) + 𝑌 ) = ( ( 𝑋 + 𝑌 ) + 𝑋 ) ) ) |
| 22 | 15 21 | mpbid | ⊢ ( ( 𝑅 ∈ Ring ∧ 𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵 ) → ( ( 𝑋 + 𝑋 ) + 𝑌 ) = ( ( 𝑋 + 𝑌 ) + 𝑋 ) ) |
| 23 | 1 2 | grpass | ⊢ ( ( 𝑅 ∈ Grp ∧ ( 𝑋 ∈ 𝐵 ∧ 𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵 ) ) → ( ( 𝑋 + 𝑋 ) + 𝑌 ) = ( 𝑋 + ( 𝑋 + 𝑌 ) ) ) |
| 24 | 5 6 6 9 23 | syl13anc | ⊢ ( ( 𝑅 ∈ Ring ∧ 𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵 ) → ( ( 𝑋 + 𝑋 ) + 𝑌 ) = ( 𝑋 + ( 𝑋 + 𝑌 ) ) ) |
| 25 | 1 2 | grpass | ⊢ ( ( 𝑅 ∈ Grp ∧ ( 𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵 ∧ 𝑋 ∈ 𝐵 ) ) → ( ( 𝑋 + 𝑌 ) + 𝑋 ) = ( 𝑋 + ( 𝑌 + 𝑋 ) ) ) |
| 26 | 5 6 9 6 25 | syl13anc | ⊢ ( ( 𝑅 ∈ Ring ∧ 𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵 ) → ( ( 𝑋 + 𝑌 ) + 𝑋 ) = ( 𝑋 + ( 𝑌 + 𝑋 ) ) ) |
| 27 | 22 24 26 | 3eqtr3d | ⊢ ( ( 𝑅 ∈ Ring ∧ 𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵 ) → ( 𝑋 + ( 𝑋 + 𝑌 ) ) = ( 𝑋 + ( 𝑌 + 𝑋 ) ) ) |
| 28 | 1 2 | ringacl | ⊢ ( ( 𝑅 ∈ Ring ∧ 𝑌 ∈ 𝐵 ∧ 𝑋 ∈ 𝐵 ) → ( 𝑌 + 𝑋 ) ∈ 𝐵 ) |
| 29 | 28 | 3com23 | ⊢ ( ( 𝑅 ∈ Ring ∧ 𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵 ) → ( 𝑌 + 𝑋 ) ∈ 𝐵 ) |
| 30 | 1 2 | grplcan | ⊢ ( ( 𝑅 ∈ Grp ∧ ( ( 𝑋 + 𝑌 ) ∈ 𝐵 ∧ ( 𝑌 + 𝑋 ) ∈ 𝐵 ∧ 𝑋 ∈ 𝐵 ) ) → ( ( 𝑋 + ( 𝑋 + 𝑌 ) ) = ( 𝑋 + ( 𝑌 + 𝑋 ) ) ↔ ( 𝑋 + 𝑌 ) = ( 𝑌 + 𝑋 ) ) ) |
| 31 | 5 12 29 6 30 | syl13anc | ⊢ ( ( 𝑅 ∈ Ring ∧ 𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵 ) → ( ( 𝑋 + ( 𝑋 + 𝑌 ) ) = ( 𝑋 + ( 𝑌 + 𝑋 ) ) ↔ ( 𝑋 + 𝑌 ) = ( 𝑌 + 𝑋 ) ) ) |
| 32 | 27 31 | mpbid | ⊢ ( ( 𝑅 ∈ Ring ∧ 𝑋 ∈ 𝐵 ∧ 𝑌 ∈ 𝐵 ) → ( 𝑋 + 𝑌 ) = ( 𝑌 + 𝑋 ) ) |