| Step | Hyp | Ref | Expression | 
						
							| 1 |  | axlowdimlem10.1 |  |-  Q = ( { <. ( I + 1 ) , 1 >. } u. ( ( ( 1 ... N ) \ { ( I + 1 ) } ) X. { 0 } ) ) | 
						
							| 2 | 1 | fveq1i |  |-  ( Q ` ( I + 1 ) ) = ( ( { <. ( I + 1 ) , 1 >. } u. ( ( ( 1 ... N ) \ { ( I + 1 ) } ) X. { 0 } ) ) ` ( I + 1 ) ) | 
						
							| 3 |  | ovex |  |-  ( I + 1 ) e. _V | 
						
							| 4 |  | 1ex |  |-  1 e. _V | 
						
							| 5 | 3 4 | fnsn |  |-  { <. ( I + 1 ) , 1 >. } Fn { ( I + 1 ) } | 
						
							| 6 |  | c0ex |  |-  0 e. _V | 
						
							| 7 | 6 | fconst |  |-  ( ( ( 1 ... N ) \ { ( I + 1 ) } ) X. { 0 } ) : ( ( 1 ... N ) \ { ( I + 1 ) } ) --> { 0 } | 
						
							| 8 |  | ffn |  |-  ( ( ( ( 1 ... N ) \ { ( I + 1 ) } ) X. { 0 } ) : ( ( 1 ... N ) \ { ( I + 1 ) } ) --> { 0 } -> ( ( ( 1 ... N ) \ { ( I + 1 ) } ) X. { 0 } ) Fn ( ( 1 ... N ) \ { ( I + 1 ) } ) ) | 
						
							| 9 | 7 8 | ax-mp |  |-  ( ( ( 1 ... N ) \ { ( I + 1 ) } ) X. { 0 } ) Fn ( ( 1 ... N ) \ { ( I + 1 ) } ) | 
						
							| 10 |  | disjdif |  |-  ( { ( I + 1 ) } i^i ( ( 1 ... N ) \ { ( I + 1 ) } ) ) = (/) | 
						
							| 11 | 3 | snid |  |-  ( I + 1 ) e. { ( I + 1 ) } | 
						
							| 12 | 10 11 | pm3.2i |  |-  ( ( { ( I + 1 ) } i^i ( ( 1 ... N ) \ { ( I + 1 ) } ) ) = (/) /\ ( I + 1 ) e. { ( I + 1 ) } ) | 
						
							| 13 |  | fvun1 |  |-  ( ( { <. ( I + 1 ) , 1 >. } Fn { ( I + 1 ) } /\ ( ( ( 1 ... N ) \ { ( I + 1 ) } ) X. { 0 } ) Fn ( ( 1 ... N ) \ { ( I + 1 ) } ) /\ ( ( { ( I + 1 ) } i^i ( ( 1 ... N ) \ { ( I + 1 ) } ) ) = (/) /\ ( I + 1 ) e. { ( I + 1 ) } ) ) -> ( ( { <. ( I + 1 ) , 1 >. } u. ( ( ( 1 ... N ) \ { ( I + 1 ) } ) X. { 0 } ) ) ` ( I + 1 ) ) = ( { <. ( I + 1 ) , 1 >. } ` ( I + 1 ) ) ) | 
						
							| 14 | 5 9 12 13 | mp3an |  |-  ( ( { <. ( I + 1 ) , 1 >. } u. ( ( ( 1 ... N ) \ { ( I + 1 ) } ) X. { 0 } ) ) ` ( I + 1 ) ) = ( { <. ( I + 1 ) , 1 >. } ` ( I + 1 ) ) | 
						
							| 15 | 3 4 | fvsn |  |-  ( { <. ( I + 1 ) , 1 >. } ` ( I + 1 ) ) = 1 | 
						
							| 16 | 2 14 15 | 3eqtri |  |-  ( Q ` ( I + 1 ) ) = 1 |