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Description: If two elements commute, then they commute with each other's inverses (case of the first element commuting with the inverse of the second element). (Contributed by SN, 29-Jan-2025)
| Ref | Expression | ||
|---|---|---|---|
| Hypotheses | grpcominv.b | ⊢ 𝐵 = ( Base ‘ 𝐺 ) | |
| grpcominv.p | ⊢ + = ( +g ‘ 𝐺 ) | ||
| grpcominv.n | ⊢ 𝑁 = ( invg ‘ 𝐺 ) | ||
| grpcominv.g | ⊢ ( 𝜑 → 𝐺 ∈ Grp ) | ||
| grpcominv.x | ⊢ ( 𝜑 → 𝑋 ∈ 𝐵 ) | ||
| grpcominv.y | ⊢ ( 𝜑 → 𝑌 ∈ 𝐵 ) | ||
| grpcominv.1 | ⊢ ( 𝜑 → ( 𝑋 + 𝑌 ) = ( 𝑌 + 𝑋 ) ) | ||
| Assertion | grpcominv1 | ⊢ ( 𝜑 → ( 𝑋 + ( 𝑁 ‘ 𝑌 ) ) = ( ( 𝑁 ‘ 𝑌 ) + 𝑋 ) ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | grpcominv.b | ⊢ 𝐵 = ( Base ‘ 𝐺 ) | |
| 2 | grpcominv.p | ⊢ + = ( +g ‘ 𝐺 ) | |
| 3 | grpcominv.n | ⊢ 𝑁 = ( invg ‘ 𝐺 ) | |
| 4 | grpcominv.g | ⊢ ( 𝜑 → 𝐺 ∈ Grp ) | |
| 5 | grpcominv.x | ⊢ ( 𝜑 → 𝑋 ∈ 𝐵 ) | |
| 6 | grpcominv.y | ⊢ ( 𝜑 → 𝑌 ∈ 𝐵 ) | |
| 7 | grpcominv.1 | ⊢ ( 𝜑 → ( 𝑋 + 𝑌 ) = ( 𝑌 + 𝑋 ) ) | |
| 8 | 1 3 4 6 | grpinvcld | ⊢ ( 𝜑 → ( 𝑁 ‘ 𝑌 ) ∈ 𝐵 ) |
| 9 | 1 2 4 8 6 5 | grpassd | ⊢ ( 𝜑 → ( ( ( 𝑁 ‘ 𝑌 ) + 𝑌 ) + 𝑋 ) = ( ( 𝑁 ‘ 𝑌 ) + ( 𝑌 + 𝑋 ) ) ) |
| 10 | eqid | ⊢ ( 0g ‘ 𝐺 ) = ( 0g ‘ 𝐺 ) | |
| 11 | 1 2 10 3 4 6 | grplinvd | ⊢ ( 𝜑 → ( ( 𝑁 ‘ 𝑌 ) + 𝑌 ) = ( 0g ‘ 𝐺 ) ) |
| 12 | 11 | oveq1d | ⊢ ( 𝜑 → ( ( ( 𝑁 ‘ 𝑌 ) + 𝑌 ) + 𝑋 ) = ( ( 0g ‘ 𝐺 ) + 𝑋 ) ) |
| 13 | 1 2 10 4 5 | grplidd | ⊢ ( 𝜑 → ( ( 0g ‘ 𝐺 ) + 𝑋 ) = 𝑋 ) |
| 14 | 12 13 | eqtr2d | ⊢ ( 𝜑 → 𝑋 = ( ( ( 𝑁 ‘ 𝑌 ) + 𝑌 ) + 𝑋 ) ) |
| 15 | 7 | oveq2d | ⊢ ( 𝜑 → ( ( 𝑁 ‘ 𝑌 ) + ( 𝑋 + 𝑌 ) ) = ( ( 𝑁 ‘ 𝑌 ) + ( 𝑌 + 𝑋 ) ) ) |
| 16 | 9 14 15 | 3eqtr4rd | ⊢ ( 𝜑 → ( ( 𝑁 ‘ 𝑌 ) + ( 𝑋 + 𝑌 ) ) = 𝑋 ) |
| 17 | 1 2 4 8 5 6 | grpassd | ⊢ ( 𝜑 → ( ( ( 𝑁 ‘ 𝑌 ) + 𝑋 ) + 𝑌 ) = ( ( 𝑁 ‘ 𝑌 ) + ( 𝑋 + 𝑌 ) ) ) |
| 18 | 1 2 3 4 5 6 | grpasscan2d | ⊢ ( 𝜑 → ( ( 𝑋 + ( 𝑁 ‘ 𝑌 ) ) + 𝑌 ) = 𝑋 ) |
| 19 | 16 17 18 | 3eqtr4rd | ⊢ ( 𝜑 → ( ( 𝑋 + ( 𝑁 ‘ 𝑌 ) ) + 𝑌 ) = ( ( ( 𝑁 ‘ 𝑌 ) + 𝑋 ) + 𝑌 ) ) |
| 20 | 1 2 4 5 8 | grpcld | ⊢ ( 𝜑 → ( 𝑋 + ( 𝑁 ‘ 𝑌 ) ) ∈ 𝐵 ) |
| 21 | 1 2 4 8 5 | grpcld | ⊢ ( 𝜑 → ( ( 𝑁 ‘ 𝑌 ) + 𝑋 ) ∈ 𝐵 ) |
| 22 | 1 2 | grprcan | ⊢ ( ( 𝐺 ∈ Grp ∧ ( ( 𝑋 + ( 𝑁 ‘ 𝑌 ) ) ∈ 𝐵 ∧ ( ( 𝑁 ‘ 𝑌 ) + 𝑋 ) ∈ 𝐵 ∧ 𝑌 ∈ 𝐵 ) ) → ( ( ( 𝑋 + ( 𝑁 ‘ 𝑌 ) ) + 𝑌 ) = ( ( ( 𝑁 ‘ 𝑌 ) + 𝑋 ) + 𝑌 ) ↔ ( 𝑋 + ( 𝑁 ‘ 𝑌 ) ) = ( ( 𝑁 ‘ 𝑌 ) + 𝑋 ) ) ) |
| 23 | 4 20 21 6 22 | syl13anc | ⊢ ( 𝜑 → ( ( ( 𝑋 + ( 𝑁 ‘ 𝑌 ) ) + 𝑌 ) = ( ( ( 𝑁 ‘ 𝑌 ) + 𝑋 ) + 𝑌 ) ↔ ( 𝑋 + ( 𝑁 ‘ 𝑌 ) ) = ( ( 𝑁 ‘ 𝑌 ) + 𝑋 ) ) ) |
| 24 | 19 23 | mpbid | ⊢ ( 𝜑 → ( 𝑋 + ( 𝑁 ‘ 𝑌 ) ) = ( ( 𝑁 ‘ 𝑌 ) + 𝑋 ) ) |