| Step | 
						Hyp | 
						Ref | 
						Expression | 
					
						
							| 1 | 
							
								
							 | 
							ocss | 
							 |-  ( A C_ ~H -> ( _|_ ` A ) C_ ~H )  | 
						
						
							| 2 | 
							
								
							 | 
							sshjval | 
							 |-  ( ( A C_ ~H /\ ( _|_ ` A ) C_ ~H ) -> ( A vH ( _|_ ` A ) ) = ( _|_ ` ( _|_ ` ( A u. ( _|_ ` A ) ) ) ) )  | 
						
						
							| 3 | 
							
								1 2
							 | 
							mpdan | 
							 |-  ( A C_ ~H -> ( A vH ( _|_ ` A ) ) = ( _|_ ` ( _|_ ` ( A u. ( _|_ ` A ) ) ) ) )  | 
						
						
							| 4 | 
							
								
							 | 
							ssun1 | 
							 |-  A C_ ( A u. ( _|_ ` A ) )  | 
						
						
							| 5 | 
							
								1
							 | 
							ancli | 
							 |-  ( A C_ ~H -> ( A C_ ~H /\ ( _|_ ` A ) C_ ~H ) )  | 
						
						
							| 6 | 
							
								
							 | 
							unss | 
							 |-  ( ( A C_ ~H /\ ( _|_ ` A ) C_ ~H ) <-> ( A u. ( _|_ ` A ) ) C_ ~H )  | 
						
						
							| 7 | 
							
								5 6
							 | 
							sylib | 
							 |-  ( A C_ ~H -> ( A u. ( _|_ ` A ) ) C_ ~H )  | 
						
						
							| 8 | 
							
								
							 | 
							occon | 
							 |-  ( ( A C_ ~H /\ ( A u. ( _|_ ` A ) ) C_ ~H ) -> ( A C_ ( A u. ( _|_ ` A ) ) -> ( _|_ ` ( A u. ( _|_ ` A ) ) ) C_ ( _|_ ` A ) ) )  | 
						
						
							| 9 | 
							
								7 8
							 | 
							mpdan | 
							 |-  ( A C_ ~H -> ( A C_ ( A u. ( _|_ ` A ) ) -> ( _|_ ` ( A u. ( _|_ ` A ) ) ) C_ ( _|_ ` A ) ) )  | 
						
						
							| 10 | 
							
								4 9
							 | 
							mpi | 
							 |-  ( A C_ ~H -> ( _|_ ` ( A u. ( _|_ ` A ) ) ) C_ ( _|_ ` A ) )  | 
						
						
							| 11 | 
							
								
							 | 
							ssun2 | 
							 |-  ( _|_ ` A ) C_ ( A u. ( _|_ ` A ) )  | 
						
						
							| 12 | 
							
								
							 | 
							occon | 
							 |-  ( ( ( _|_ ` A ) C_ ~H /\ ( A u. ( _|_ ` A ) ) C_ ~H ) -> ( ( _|_ ` A ) C_ ( A u. ( _|_ ` A ) ) -> ( _|_ ` ( A u. ( _|_ ` A ) ) ) C_ ( _|_ ` ( _|_ ` A ) ) ) )  | 
						
						
							| 13 | 
							
								1 7 12
							 | 
							syl2anc | 
							 |-  ( A C_ ~H -> ( ( _|_ ` A ) C_ ( A u. ( _|_ ` A ) ) -> ( _|_ ` ( A u. ( _|_ ` A ) ) ) C_ ( _|_ ` ( _|_ ` A ) ) ) )  | 
						
						
							| 14 | 
							
								11 13
							 | 
							mpi | 
							 |-  ( A C_ ~H -> ( _|_ ` ( A u. ( _|_ ` A ) ) ) C_ ( _|_ ` ( _|_ ` A ) ) )  | 
						
						
							| 15 | 
							
								10 14
							 | 
							ssind | 
							 |-  ( A C_ ~H -> ( _|_ ` ( A u. ( _|_ ` A ) ) ) C_ ( ( _|_ ` A ) i^i ( _|_ ` ( _|_ ` A ) ) ) )  | 
						
						
							| 16 | 
							
								
							 | 
							ocsh | 
							 |-  ( A C_ ~H -> ( _|_ ` A ) e. SH )  | 
						
						
							| 17 | 
							
								
							 | 
							ocin | 
							 |-  ( ( _|_ ` A ) e. SH -> ( ( _|_ ` A ) i^i ( _|_ ` ( _|_ ` A ) ) ) = 0H )  | 
						
						
							| 18 | 
							
								16 17
							 | 
							syl | 
							 |-  ( A C_ ~H -> ( ( _|_ ` A ) i^i ( _|_ ` ( _|_ ` A ) ) ) = 0H )  | 
						
						
							| 19 | 
							
								15 18
							 | 
							sseqtrd | 
							 |-  ( A C_ ~H -> ( _|_ ` ( A u. ( _|_ ` A ) ) ) C_ 0H )  | 
						
						
							| 20 | 
							
								
							 | 
							ocsh | 
							 |-  ( ( A u. ( _|_ ` A ) ) C_ ~H -> ( _|_ ` ( A u. ( _|_ ` A ) ) ) e. SH )  | 
						
						
							| 21 | 
							
								
							 | 
							sh0le | 
							 |-  ( ( _|_ ` ( A u. ( _|_ ` A ) ) ) e. SH -> 0H C_ ( _|_ ` ( A u. ( _|_ ` A ) ) ) )  | 
						
						
							| 22 | 
							
								7 20 21
							 | 
							3syl | 
							 |-  ( A C_ ~H -> 0H C_ ( _|_ ` ( A u. ( _|_ ` A ) ) ) )  | 
						
						
							| 23 | 
							
								19 22
							 | 
							eqssd | 
							 |-  ( A C_ ~H -> ( _|_ ` ( A u. ( _|_ ` A ) ) ) = 0H )  | 
						
						
							| 24 | 
							
								23
							 | 
							fveq2d | 
							 |-  ( A C_ ~H -> ( _|_ ` ( _|_ ` ( A u. ( _|_ ` A ) ) ) ) = ( _|_ ` 0H ) )  | 
						
						
							| 25 | 
							
								
							 | 
							choc0 | 
							 |-  ( _|_ ` 0H ) = ~H  | 
						
						
							| 26 | 
							
								24 25
							 | 
							eqtrdi | 
							 |-  ( A C_ ~H -> ( _|_ ` ( _|_ ` ( A u. ( _|_ ` A ) ) ) ) = ~H )  | 
						
						
							| 27 | 
							
								3 26
							 | 
							eqtrd | 
							 |-  ( A C_ ~H -> ( A vH ( _|_ ` A ) ) = ~H )  |