| Step | Hyp | Ref | Expression | 
						
							| 1 |  | zlmodzxz.z |  |-  Z = ( ZZring freeLMod { 0 , 1 } ) | 
						
							| 2 |  | zlmodzxz.o |  |-  .0. = { <. 0 , 0 >. , <. 1 , 0 >. } | 
						
							| 3 |  | c0ex |  |-  0 e. _V | 
						
							| 4 |  | 1ex |  |-  1 e. _V | 
						
							| 5 |  | xpprsng |  |-  ( ( 0 e. _V /\ 1 e. _V /\ 0 e. _V ) -> ( { 0 , 1 } X. { 0 } ) = { <. 0 , 0 >. , <. 1 , 0 >. } ) | 
						
							| 6 | 3 4 3 5 | mp3an |  |-  ( { 0 , 1 } X. { 0 } ) = { <. 0 , 0 >. , <. 1 , 0 >. } | 
						
							| 7 |  | zringring |  |-  ZZring e. Ring | 
						
							| 8 |  | prex |  |-  { 0 , 1 } e. _V | 
						
							| 9 |  | zring0 |  |-  0 = ( 0g ` ZZring ) | 
						
							| 10 | 1 9 | frlm0 |  |-  ( ( ZZring e. Ring /\ { 0 , 1 } e. _V ) -> ( { 0 , 1 } X. { 0 } ) = ( 0g ` Z ) ) | 
						
							| 11 | 7 8 10 | mp2an |  |-  ( { 0 , 1 } X. { 0 } ) = ( 0g ` Z ) | 
						
							| 12 | 2 6 11 | 3eqtr2i |  |-  .0. = ( 0g ` Z ) |