| Step | Hyp | Ref | Expression | 
						
							| 1 |  | zaddablx.g | ⊢ 𝐺  =  { 〈 1 ,  ℤ 〉 ,  〈 2 ,   +  〉 } | 
						
							| 2 |  | zex | ⊢ ℤ  ∈  V | 
						
							| 3 |  | addex | ⊢  +   ∈  V | 
						
							| 4 |  | zaddcl | ⊢ ( ( 𝑥  ∈  ℤ  ∧  𝑦  ∈  ℤ )  →  ( 𝑥  +  𝑦 )  ∈  ℤ ) | 
						
							| 5 |  | zcn | ⊢ ( 𝑥  ∈  ℤ  →  𝑥  ∈  ℂ ) | 
						
							| 6 |  | zcn | ⊢ ( 𝑦  ∈  ℤ  →  𝑦  ∈  ℂ ) | 
						
							| 7 |  | zcn | ⊢ ( 𝑧  ∈  ℤ  →  𝑧  ∈  ℂ ) | 
						
							| 8 |  | addass | ⊢ ( ( 𝑥  ∈  ℂ  ∧  𝑦  ∈  ℂ  ∧  𝑧  ∈  ℂ )  →  ( ( 𝑥  +  𝑦 )  +  𝑧 )  =  ( 𝑥  +  ( 𝑦  +  𝑧 ) ) ) | 
						
							| 9 | 5 6 7 8 | syl3an | ⊢ ( ( 𝑥  ∈  ℤ  ∧  𝑦  ∈  ℤ  ∧  𝑧  ∈  ℤ )  →  ( ( 𝑥  +  𝑦 )  +  𝑧 )  =  ( 𝑥  +  ( 𝑦  +  𝑧 ) ) ) | 
						
							| 10 |  | 0z | ⊢ 0  ∈  ℤ | 
						
							| 11 | 5 | addlidd | ⊢ ( 𝑥  ∈  ℤ  →  ( 0  +  𝑥 )  =  𝑥 ) | 
						
							| 12 |  | znegcl | ⊢ ( 𝑥  ∈  ℤ  →  - 𝑥  ∈  ℤ ) | 
						
							| 13 |  | zcn | ⊢ ( - 𝑥  ∈  ℤ  →  - 𝑥  ∈  ℂ ) | 
						
							| 14 |  | addcom | ⊢ ( ( 𝑥  ∈  ℂ  ∧  - 𝑥  ∈  ℂ )  →  ( 𝑥  +  - 𝑥 )  =  ( - 𝑥  +  𝑥 ) ) | 
						
							| 15 | 5 13 14 | syl2an | ⊢ ( ( 𝑥  ∈  ℤ  ∧  - 𝑥  ∈  ℤ )  →  ( 𝑥  +  - 𝑥 )  =  ( - 𝑥  +  𝑥 ) ) | 
						
							| 16 | 12 15 | mpdan | ⊢ ( 𝑥  ∈  ℤ  →  ( 𝑥  +  - 𝑥 )  =  ( - 𝑥  +  𝑥 ) ) | 
						
							| 17 | 5 | negidd | ⊢ ( 𝑥  ∈  ℤ  →  ( 𝑥  +  - 𝑥 )  =  0 ) | 
						
							| 18 | 16 17 | eqtr3d | ⊢ ( 𝑥  ∈  ℤ  →  ( - 𝑥  +  𝑥 )  =  0 ) | 
						
							| 19 | 2 3 1 4 9 10 11 12 18 | isgrpix | ⊢ 𝐺  ∈  Grp | 
						
							| 20 | 2 3 1 | grpbasex | ⊢ ℤ  =  ( Base ‘ 𝐺 ) | 
						
							| 21 | 2 3 1 | grpplusgx | ⊢  +   =  ( +g ‘ 𝐺 ) | 
						
							| 22 |  | addcom | ⊢ ( ( 𝑥  ∈  ℂ  ∧  𝑦  ∈  ℂ )  →  ( 𝑥  +  𝑦 )  =  ( 𝑦  +  𝑥 ) ) | 
						
							| 23 | 5 6 22 | syl2an | ⊢ ( ( 𝑥  ∈  ℤ  ∧  𝑦  ∈  ℤ )  →  ( 𝑥  +  𝑦 )  =  ( 𝑦  +  𝑥 ) ) | 
						
							| 24 | 19 20 21 23 | isabli | ⊢ 𝐺  ∈  Abel |