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Description: Addition of complex numbers is associative. Axiom 9 of 22 for real and complex numbers, justified by Theorem axaddass . Proofs should normally use addass instead. (New usage is discouraged.) (Contributed by NM, 22-Nov-1994)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | ax-addass | ⊢ ( ( 𝐴 ∈ ℂ ∧ 𝐵 ∈ ℂ ∧ 𝐶 ∈ ℂ ) → ( ( 𝐴 + 𝐵 ) + 𝐶 ) = ( 𝐴 + ( 𝐵 + 𝐶 ) ) ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 0 | cA | ⊢ 𝐴 | |
| 1 | cc | ⊢ ℂ | |
| 2 | 0 1 | wcel | ⊢ 𝐴 ∈ ℂ |
| 3 | cB | ⊢ 𝐵 | |
| 4 | 3 1 | wcel | ⊢ 𝐵 ∈ ℂ |
| 5 | cC | ⊢ 𝐶 | |
| 6 | 5 1 | wcel | ⊢ 𝐶 ∈ ℂ |
| 7 | 2 4 6 | w3a | ⊢ ( 𝐴 ∈ ℂ ∧ 𝐵 ∈ ℂ ∧ 𝐶 ∈ ℂ ) |
| 8 | caddc | ⊢ + | |
| 9 | 0 3 8 | co | ⊢ ( 𝐴 + 𝐵 ) |
| 10 | 9 5 8 | co | ⊢ ( ( 𝐴 + 𝐵 ) + 𝐶 ) |
| 11 | 3 5 8 | co | ⊢ ( 𝐵 + 𝐶 ) |
| 12 | 0 11 8 | co | ⊢ ( 𝐴 + ( 𝐵 + 𝐶 ) ) |
| 13 | 10 12 | wceq | ⊢ ( ( 𝐴 + 𝐵 ) + 𝐶 ) = ( 𝐴 + ( 𝐵 + 𝐶 ) ) |
| 14 | 7 13 | wi | ⊢ ( ( 𝐴 ∈ ℂ ∧ 𝐵 ∈ ℂ ∧ 𝐶 ∈ ℂ ) → ( ( 𝐴 + 𝐵 ) + 𝐶 ) = ( 𝐴 + ( 𝐵 + 𝐶 ) ) ) |