| Step | Hyp | Ref | Expression | 
						
							| 1 |  | zaddablx.g |  |-  G = { <. 1 , ZZ >. , <. 2 , + >. } | 
						
							| 2 |  | zex |  |-  ZZ e. _V | 
						
							| 3 |  | addex |  |-  + e. _V | 
						
							| 4 |  | zaddcl |  |-  ( ( x e. ZZ /\ y e. ZZ ) -> ( x + y ) e. ZZ ) | 
						
							| 5 |  | zcn |  |-  ( x e. ZZ -> x e. CC ) | 
						
							| 6 |  | zcn |  |-  ( y e. ZZ -> y e. CC ) | 
						
							| 7 |  | zcn |  |-  ( z e. ZZ -> z e. CC ) | 
						
							| 8 |  | addass |  |-  ( ( x e. CC /\ y e. CC /\ z e. CC ) -> ( ( x + y ) + z ) = ( x + ( y + z ) ) ) | 
						
							| 9 | 5 6 7 8 | syl3an |  |-  ( ( x e. ZZ /\ y e. ZZ /\ z e. ZZ ) -> ( ( x + y ) + z ) = ( x + ( y + z ) ) ) | 
						
							| 10 |  | 0z |  |-  0 e. ZZ | 
						
							| 11 | 5 | addlidd |  |-  ( x e. ZZ -> ( 0 + x ) = x ) | 
						
							| 12 |  | znegcl |  |-  ( x e. ZZ -> -u x e. ZZ ) | 
						
							| 13 |  | zcn |  |-  ( -u x e. ZZ -> -u x e. CC ) | 
						
							| 14 |  | addcom |  |-  ( ( x e. CC /\ -u x e. CC ) -> ( x + -u x ) = ( -u x + x ) ) | 
						
							| 15 | 5 13 14 | syl2an |  |-  ( ( x e. ZZ /\ -u x e. ZZ ) -> ( x + -u x ) = ( -u x + x ) ) | 
						
							| 16 | 12 15 | mpdan |  |-  ( x e. ZZ -> ( x + -u x ) = ( -u x + x ) ) | 
						
							| 17 | 5 | negidd |  |-  ( x e. ZZ -> ( x + -u x ) = 0 ) | 
						
							| 18 | 16 17 | eqtr3d |  |-  ( x e. ZZ -> ( -u x + x ) = 0 ) | 
						
							| 19 | 2 3 1 4 9 10 11 12 18 | isgrpix |  |-  G e. Grp | 
						
							| 20 | 2 3 1 | grpbasex |  |-  ZZ = ( Base ` G ) | 
						
							| 21 | 2 3 1 | grpplusgx |  |-  + = ( +g ` G ) | 
						
							| 22 |  | addcom |  |-  ( ( x e. CC /\ y e. CC ) -> ( x + y ) = ( y + x ) ) | 
						
							| 23 | 5 6 22 | syl2an |  |-  ( ( x e. ZZ /\ y e. ZZ ) -> ( x + y ) = ( y + x ) ) | 
						
							| 24 | 19 20 21 23 | isabli |  |-  G e. Abel |