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Description: Transfer a commutative law to the function operation. (Contributed by Mario Carneiro, 26-Jul-2014)
| Ref | Expression | ||
|---|---|---|---|
| Hypotheses | caofref.1 | ⊢ ( 𝜑 → 𝐴 ∈ 𝑉 ) | |
| caofref.2 | ⊢ ( 𝜑 → 𝐹 : 𝐴 ⟶ 𝑆 ) | ||
| caofcom.3 | ⊢ ( 𝜑 → 𝐺 : 𝐴 ⟶ 𝑆 ) | ||
| caofcom.4 | ⊢ ( ( 𝜑 ∧ ( 𝑥 ∈ 𝑆 ∧ 𝑦 ∈ 𝑆 ) ) → ( 𝑥 𝑅 𝑦 ) = ( 𝑦 𝑅 𝑥 ) ) | ||
| Assertion | caofcom | ⊢ ( 𝜑 → ( 𝐹 ∘f 𝑅 𝐺 ) = ( 𝐺 ∘f 𝑅 𝐹 ) ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | caofref.1 | ⊢ ( 𝜑 → 𝐴 ∈ 𝑉 ) | |
| 2 | caofref.2 | ⊢ ( 𝜑 → 𝐹 : 𝐴 ⟶ 𝑆 ) | |
| 3 | caofcom.3 | ⊢ ( 𝜑 → 𝐺 : 𝐴 ⟶ 𝑆 ) | |
| 4 | caofcom.4 | ⊢ ( ( 𝜑 ∧ ( 𝑥 ∈ 𝑆 ∧ 𝑦 ∈ 𝑆 ) ) → ( 𝑥 𝑅 𝑦 ) = ( 𝑦 𝑅 𝑥 ) ) | |
| 5 | 2 | ffvelcdmda | ⊢ ( ( 𝜑 ∧ 𝑤 ∈ 𝐴 ) → ( 𝐹 ‘ 𝑤 ) ∈ 𝑆 ) |
| 6 | 3 | ffvelcdmda | ⊢ ( ( 𝜑 ∧ 𝑤 ∈ 𝐴 ) → ( 𝐺 ‘ 𝑤 ) ∈ 𝑆 ) |
| 7 | 5 6 | jca | ⊢ ( ( 𝜑 ∧ 𝑤 ∈ 𝐴 ) → ( ( 𝐹 ‘ 𝑤 ) ∈ 𝑆 ∧ ( 𝐺 ‘ 𝑤 ) ∈ 𝑆 ) ) |
| 8 | 4 | caovcomg | ⊢ ( ( 𝜑 ∧ ( ( 𝐹 ‘ 𝑤 ) ∈ 𝑆 ∧ ( 𝐺 ‘ 𝑤 ) ∈ 𝑆 ) ) → ( ( 𝐹 ‘ 𝑤 ) 𝑅 ( 𝐺 ‘ 𝑤 ) ) = ( ( 𝐺 ‘ 𝑤 ) 𝑅 ( 𝐹 ‘ 𝑤 ) ) ) |
| 9 | 7 8 | syldan | ⊢ ( ( 𝜑 ∧ 𝑤 ∈ 𝐴 ) → ( ( 𝐹 ‘ 𝑤 ) 𝑅 ( 𝐺 ‘ 𝑤 ) ) = ( ( 𝐺 ‘ 𝑤 ) 𝑅 ( 𝐹 ‘ 𝑤 ) ) ) |
| 10 | 9 | mpteq2dva | ⊢ ( 𝜑 → ( 𝑤 ∈ 𝐴 ↦ ( ( 𝐹 ‘ 𝑤 ) 𝑅 ( 𝐺 ‘ 𝑤 ) ) ) = ( 𝑤 ∈ 𝐴 ↦ ( ( 𝐺 ‘ 𝑤 ) 𝑅 ( 𝐹 ‘ 𝑤 ) ) ) ) |
| 11 | 2 | feqmptd | ⊢ ( 𝜑 → 𝐹 = ( 𝑤 ∈ 𝐴 ↦ ( 𝐹 ‘ 𝑤 ) ) ) |
| 12 | 3 | feqmptd | ⊢ ( 𝜑 → 𝐺 = ( 𝑤 ∈ 𝐴 ↦ ( 𝐺 ‘ 𝑤 ) ) ) |
| 13 | 1 5 6 11 12 | offval2 | ⊢ ( 𝜑 → ( 𝐹 ∘f 𝑅 𝐺 ) = ( 𝑤 ∈ 𝐴 ↦ ( ( 𝐹 ‘ 𝑤 ) 𝑅 ( 𝐺 ‘ 𝑤 ) ) ) ) |
| 14 | 1 6 5 12 11 | offval2 | ⊢ ( 𝜑 → ( 𝐺 ∘f 𝑅 𝐹 ) = ( 𝑤 ∈ 𝐴 ↦ ( ( 𝐺 ‘ 𝑤 ) 𝑅 ( 𝐹 ‘ 𝑤 ) ) ) ) |
| 15 | 10 13 14 | 3eqtr4d | ⊢ ( 𝜑 → ( 𝐹 ∘f 𝑅 𝐺 ) = ( 𝐺 ∘f 𝑅 𝐹 ) ) |