| Step | Hyp | Ref | Expression | 
						
							| 1 |  | large.1 |  |-  A e. CH | 
						
							| 2 |  | ralnex |  |-  ( A. f e. States -. ( f ` A ) = 1 <-> -. E. f e. States ( f ` A ) = 1 ) | 
						
							| 3 |  | ax-1ne0 |  |-  1 =/= 0 | 
						
							| 4 | 3 | neii |  |-  -. 1 = 0 | 
						
							| 5 |  | st0 |  |-  ( f e. States -> ( f ` 0H ) = 0 ) | 
						
							| 6 | 5 | eqeq1d |  |-  ( f e. States -> ( ( f ` 0H ) = 1 <-> 0 = 1 ) ) | 
						
							| 7 |  | eqcom |  |-  ( 0 = 1 <-> 1 = 0 ) | 
						
							| 8 | 6 7 | bitrdi |  |-  ( f e. States -> ( ( f ` 0H ) = 1 <-> 1 = 0 ) ) | 
						
							| 9 | 4 8 | mtbiri |  |-  ( f e. States -> -. ( f ` 0H ) = 1 ) | 
						
							| 10 |  | mtt |  |-  ( -. ( f ` 0H ) = 1 -> ( -. ( f ` A ) = 1 <-> ( ( f ` A ) = 1 -> ( f ` 0H ) = 1 ) ) ) | 
						
							| 11 | 9 10 | syl |  |-  ( f e. States -> ( -. ( f ` A ) = 1 <-> ( ( f ` A ) = 1 -> ( f ` 0H ) = 1 ) ) ) | 
						
							| 12 | 11 | ralbiia |  |-  ( A. f e. States -. ( f ` A ) = 1 <-> A. f e. States ( ( f ` A ) = 1 -> ( f ` 0H ) = 1 ) ) | 
						
							| 13 |  | h0elch |  |-  0H e. CH | 
						
							| 14 | 1 13 | strb |  |-  ( A. f e. States ( ( f ` A ) = 1 -> ( f ` 0H ) = 1 ) <-> A C_ 0H ) | 
						
							| 15 | 1 | chle0i |  |-  ( A C_ 0H <-> A = 0H ) | 
						
							| 16 | 12 14 15 | 3bitri |  |-  ( A. f e. States -. ( f ` A ) = 1 <-> A = 0H ) | 
						
							| 17 | 2 16 | bitr3i |  |-  ( -. E. f e. States ( f ` A ) = 1 <-> A = 0H ) | 
						
							| 18 | 17 | con1bii |  |-  ( -. A = 0H <-> E. f e. States ( f ` A ) = 1 ) |