| Step | Hyp | Ref | Expression | 
						
							| 1 |  | sto1.1 |  |-  A e. CH | 
						
							| 2 | 1 | chjoi |  |-  ( A vH ( _|_ ` A ) ) = ~H | 
						
							| 3 | 2 | fveq2i |  |-  ( S ` ( A vH ( _|_ ` A ) ) ) = ( S ` ~H ) | 
						
							| 4 | 1 | choccli |  |-  ( _|_ ` A ) e. CH | 
						
							| 5 | 1 4 | pm3.2i |  |-  ( A e. CH /\ ( _|_ ` A ) e. CH ) | 
						
							| 6 | 1 | chshii |  |-  A e. SH | 
						
							| 7 |  | shococss |  |-  ( A e. SH -> A C_ ( _|_ ` ( _|_ ` A ) ) ) | 
						
							| 8 | 6 7 | ax-mp |  |-  A C_ ( _|_ ` ( _|_ ` A ) ) | 
						
							| 9 |  | stj |  |-  ( S e. States -> ( ( ( A e. CH /\ ( _|_ ` A ) e. CH ) /\ A C_ ( _|_ ` ( _|_ ` A ) ) ) -> ( S ` ( A vH ( _|_ ` A ) ) ) = ( ( S ` A ) + ( S ` ( _|_ ` A ) ) ) ) ) | 
						
							| 10 | 5 8 9 | mp2ani |  |-  ( S e. States -> ( S ` ( A vH ( _|_ ` A ) ) ) = ( ( S ` A ) + ( S ` ( _|_ ` A ) ) ) ) | 
						
							| 11 |  | sthil |  |-  ( S e. States -> ( S ` ~H ) = 1 ) | 
						
							| 12 | 3 10 11 | 3eqtr3a |  |-  ( S e. States -> ( ( S ` A ) + ( S ` ( _|_ ` A ) ) ) = 1 ) |