| Step | Hyp | Ref | Expression | 
						
							| 1 |  | nonbool.1 |  |-  A e. ~H | 
						
							| 2 |  | nonbool.2 |  |-  B e. ~H | 
						
							| 3 |  | nonbool.3 |  |-  F = ( span ` { A } ) | 
						
							| 4 |  | nonbool.4 |  |-  G = ( span ` { B } ) | 
						
							| 5 |  | nonbool.5 |  |-  H = ( span ` { ( A +h B ) } ) | 
						
							| 6 | 1 2 | hvaddcli |  |-  ( A +h B ) e. ~H | 
						
							| 7 |  | spansnid |  |-  ( ( A +h B ) e. ~H -> ( A +h B ) e. ( span ` { ( A +h B ) } ) ) | 
						
							| 8 | 6 7 | ax-mp |  |-  ( A +h B ) e. ( span ` { ( A +h B ) } ) | 
						
							| 9 | 8 5 | eleqtrri |  |-  ( A +h B ) e. H | 
						
							| 10 | 1 | spansnchi |  |-  ( span ` { A } ) e. CH | 
						
							| 11 | 10 | chshii |  |-  ( span ` { A } ) e. SH | 
						
							| 12 | 3 11 | eqeltri |  |-  F e. SH | 
						
							| 13 | 2 | spansnchi |  |-  ( span ` { B } ) e. CH | 
						
							| 14 | 13 | chshii |  |-  ( span ` { B } ) e. SH | 
						
							| 15 | 4 14 | eqeltri |  |-  G e. SH | 
						
							| 16 | 12 15 | shsleji |  |-  ( F +H G ) C_ ( F vH G ) | 
						
							| 17 |  | spansnid |  |-  ( A e. ~H -> A e. ( span ` { A } ) ) | 
						
							| 18 | 1 17 | ax-mp |  |-  A e. ( span ` { A } ) | 
						
							| 19 | 18 3 | eleqtrri |  |-  A e. F | 
						
							| 20 |  | spansnid |  |-  ( B e. ~H -> B e. ( span ` { B } ) ) | 
						
							| 21 | 2 20 | ax-mp |  |-  B e. ( span ` { B } ) | 
						
							| 22 | 21 4 | eleqtrri |  |-  B e. G | 
						
							| 23 | 12 15 | shsvai |  |-  ( ( A e. F /\ B e. G ) -> ( A +h B ) e. ( F +H G ) ) | 
						
							| 24 | 19 22 23 | mp2an |  |-  ( A +h B ) e. ( F +H G ) | 
						
							| 25 | 16 24 | sselii |  |-  ( A +h B ) e. ( F vH G ) | 
						
							| 26 |  | elin |  |-  ( ( A +h B ) e. ( H i^i ( F vH G ) ) <-> ( ( A +h B ) e. H /\ ( A +h B ) e. ( F vH G ) ) ) | 
						
							| 27 | 9 25 26 | mpbir2an |  |-  ( A +h B ) e. ( H i^i ( F vH G ) ) | 
						
							| 28 |  | eleq2 |  |-  ( ( H i^i ( F vH G ) ) = 0H -> ( ( A +h B ) e. ( H i^i ( F vH G ) ) <-> ( A +h B ) e. 0H ) ) | 
						
							| 29 | 27 28 | mpbii |  |-  ( ( H i^i ( F vH G ) ) = 0H -> ( A +h B ) e. 0H ) | 
						
							| 30 |  | elch0 |  |-  ( ( A +h B ) e. 0H <-> ( A +h B ) = 0h ) | 
						
							| 31 | 29 30 | sylib |  |-  ( ( H i^i ( F vH G ) ) = 0H -> ( A +h B ) = 0h ) | 
						
							| 32 |  | ch0 |  |-  ( ( span ` { A } ) e. CH -> 0h e. ( span ` { A } ) ) | 
						
							| 33 | 10 32 | ax-mp |  |-  0h e. ( span ` { A } ) | 
						
							| 34 | 31 33 | eqeltrdi |  |-  ( ( H i^i ( F vH G ) ) = 0H -> ( A +h B ) e. ( span ` { A } ) ) | 
						
							| 35 | 3 | eleq2i |  |-  ( B e. F <-> B e. ( span ` { A } ) ) | 
						
							| 36 |  | sumspansn |  |-  ( ( A e. ~H /\ B e. ~H ) -> ( ( A +h B ) e. ( span ` { A } ) <-> B e. ( span ` { A } ) ) ) | 
						
							| 37 | 1 2 36 | mp2an |  |-  ( ( A +h B ) e. ( span ` { A } ) <-> B e. ( span ` { A } ) ) | 
						
							| 38 | 35 37 | bitr4i |  |-  ( B e. F <-> ( A +h B ) e. ( span ` { A } ) ) | 
						
							| 39 | 34 38 | sylibr |  |-  ( ( H i^i ( F vH G ) ) = 0H -> B e. F ) | 
						
							| 40 | 39 | con3i |  |-  ( -. B e. F -> -. ( H i^i ( F vH G ) ) = 0H ) | 
						
							| 41 | 40 | adantl |  |-  ( ( -. A e. G /\ -. B e. F ) -> -. ( H i^i ( F vH G ) ) = 0H ) | 
						
							| 42 | 5 3 | ineq12i |  |-  ( H i^i F ) = ( ( span ` { ( A +h B ) } ) i^i ( span ` { A } ) ) | 
						
							| 43 | 6 1 | spansnm0i |  |-  ( -. ( A +h B ) e. ( span ` { A } ) -> ( ( span ` { ( A +h B ) } ) i^i ( span ` { A } ) ) = 0H ) | 
						
							| 44 | 38 43 | sylnbi |  |-  ( -. B e. F -> ( ( span ` { ( A +h B ) } ) i^i ( span ` { A } ) ) = 0H ) | 
						
							| 45 | 42 44 | eqtrid |  |-  ( -. B e. F -> ( H i^i F ) = 0H ) | 
						
							| 46 | 5 4 | ineq12i |  |-  ( H i^i G ) = ( ( span ` { ( A +h B ) } ) i^i ( span ` { B } ) ) | 
						
							| 47 |  | sumspansn |  |-  ( ( B e. ~H /\ A e. ~H ) -> ( ( B +h A ) e. ( span ` { B } ) <-> A e. ( span ` { B } ) ) ) | 
						
							| 48 | 2 1 47 | mp2an |  |-  ( ( B +h A ) e. ( span ` { B } ) <-> A e. ( span ` { B } ) ) | 
						
							| 49 | 1 2 | hvcomi |  |-  ( A +h B ) = ( B +h A ) | 
						
							| 50 | 49 | eleq1i |  |-  ( ( A +h B ) e. ( span ` { B } ) <-> ( B +h A ) e. ( span ` { B } ) ) | 
						
							| 51 | 4 | eleq2i |  |-  ( A e. G <-> A e. ( span ` { B } ) ) | 
						
							| 52 | 48 50 51 | 3bitr4ri |  |-  ( A e. G <-> ( A +h B ) e. ( span ` { B } ) ) | 
						
							| 53 | 6 2 | spansnm0i |  |-  ( -. ( A +h B ) e. ( span ` { B } ) -> ( ( span ` { ( A +h B ) } ) i^i ( span ` { B } ) ) = 0H ) | 
						
							| 54 | 52 53 | sylnbi |  |-  ( -. A e. G -> ( ( span ` { ( A +h B ) } ) i^i ( span ` { B } ) ) = 0H ) | 
						
							| 55 | 46 54 | eqtrid |  |-  ( -. A e. G -> ( H i^i G ) = 0H ) | 
						
							| 56 | 45 55 | oveqan12rd |  |-  ( ( -. A e. G /\ -. B e. F ) -> ( ( H i^i F ) vH ( H i^i G ) ) = ( 0H vH 0H ) ) | 
						
							| 57 |  | h0elch |  |-  0H e. CH | 
						
							| 58 | 57 | chj0i |  |-  ( 0H vH 0H ) = 0H | 
						
							| 59 | 56 58 | eqtrdi |  |-  ( ( -. A e. G /\ -. B e. F ) -> ( ( H i^i F ) vH ( H i^i G ) ) = 0H ) | 
						
							| 60 |  | eqeq2 |  |-  ( ( ( H i^i F ) vH ( H i^i G ) ) = 0H -> ( ( H i^i ( F vH G ) ) = ( ( H i^i F ) vH ( H i^i G ) ) <-> ( H i^i ( F vH G ) ) = 0H ) ) | 
						
							| 61 | 60 | notbid |  |-  ( ( ( H i^i F ) vH ( H i^i G ) ) = 0H -> ( -. ( H i^i ( F vH G ) ) = ( ( H i^i F ) vH ( H i^i G ) ) <-> -. ( H i^i ( F vH G ) ) = 0H ) ) | 
						
							| 62 | 61 | biimparc |  |-  ( ( -. ( H i^i ( F vH G ) ) = 0H /\ ( ( H i^i F ) vH ( H i^i G ) ) = 0H ) -> -. ( H i^i ( F vH G ) ) = ( ( H i^i F ) vH ( H i^i G ) ) ) | 
						
							| 63 | 41 59 62 | syl2anc |  |-  ( ( -. A e. G /\ -. B e. F ) -> -. ( H i^i ( F vH G ) ) = ( ( H i^i F ) vH ( H i^i G ) ) ) | 
						
							| 64 |  | ioran |  |-  ( -. ( A e. G \/ B e. F ) <-> ( -. A e. G /\ -. B e. F ) ) | 
						
							| 65 |  | df-ne |  |-  ( ( H i^i ( F vH G ) ) =/= ( ( H i^i F ) vH ( H i^i G ) ) <-> -. ( H i^i ( F vH G ) ) = ( ( H i^i F ) vH ( H i^i G ) ) ) | 
						
							| 66 | 63 64 65 | 3imtr4i |  |-  ( -. ( A e. G \/ B e. F ) -> ( H i^i ( F vH G ) ) =/= ( ( H i^i F ) vH ( H i^i G ) ) ) |