| Step | Hyp | Ref | Expression | 
						
							| 1 |  | mdslmd.1 |  |-  A e. CH | 
						
							| 2 |  | mdslmd.2 |  |-  B e. CH | 
						
							| 3 |  | mdslmd.3 |  |-  C e. CH | 
						
							| 4 |  | mdslmd.4 |  |-  D e. CH | 
						
							| 5 |  | mddmd |  |-  ( ( A e. CH /\ B e. CH ) -> ( A MH B <-> ( _|_ ` A ) MH* ( _|_ ` B ) ) ) | 
						
							| 6 | 1 2 5 | mp2an |  |-  ( A MH B <-> ( _|_ ` A ) MH* ( _|_ ` B ) ) | 
						
							| 7 |  | dmdmd |  |-  ( ( B e. CH /\ A e. CH ) -> ( B MH* A <-> ( _|_ ` B ) MH ( _|_ ` A ) ) ) | 
						
							| 8 | 2 1 7 | mp2an |  |-  ( B MH* A <-> ( _|_ ` B ) MH ( _|_ ` A ) ) | 
						
							| 9 | 6 8 | anbi12ci |  |-  ( ( A MH B /\ B MH* A ) <-> ( ( _|_ ` B ) MH ( _|_ ` A ) /\ ( _|_ ` A ) MH* ( _|_ ` B ) ) ) | 
						
							| 10 | 3 4 | chincli |  |-  ( C i^i D ) e. CH | 
						
							| 11 | 1 10 | chsscon3i |  |-  ( A C_ ( C i^i D ) <-> ( _|_ ` ( C i^i D ) ) C_ ( _|_ ` A ) ) | 
						
							| 12 | 3 4 | chdmm1i |  |-  ( _|_ ` ( C i^i D ) ) = ( ( _|_ ` C ) vH ( _|_ ` D ) ) | 
						
							| 13 | 12 | sseq1i |  |-  ( ( _|_ ` ( C i^i D ) ) C_ ( _|_ ` A ) <-> ( ( _|_ ` C ) vH ( _|_ ` D ) ) C_ ( _|_ ` A ) ) | 
						
							| 14 | 11 13 | bitri |  |-  ( A C_ ( C i^i D ) <-> ( ( _|_ ` C ) vH ( _|_ ` D ) ) C_ ( _|_ ` A ) ) | 
						
							| 15 | 3 4 | chjcli |  |-  ( C vH D ) e. CH | 
						
							| 16 | 1 2 | chjcli |  |-  ( A vH B ) e. CH | 
						
							| 17 | 15 16 | chsscon3i |  |-  ( ( C vH D ) C_ ( A vH B ) <-> ( _|_ ` ( A vH B ) ) C_ ( _|_ ` ( C vH D ) ) ) | 
						
							| 18 | 1 2 | chdmj1i |  |-  ( _|_ ` ( A vH B ) ) = ( ( _|_ ` A ) i^i ( _|_ ` B ) ) | 
						
							| 19 |  | incom |  |-  ( ( _|_ ` A ) i^i ( _|_ ` B ) ) = ( ( _|_ ` B ) i^i ( _|_ ` A ) ) | 
						
							| 20 | 18 19 | eqtri |  |-  ( _|_ ` ( A vH B ) ) = ( ( _|_ ` B ) i^i ( _|_ ` A ) ) | 
						
							| 21 | 3 4 | chdmj1i |  |-  ( _|_ ` ( C vH D ) ) = ( ( _|_ ` C ) i^i ( _|_ ` D ) ) | 
						
							| 22 | 20 21 | sseq12i |  |-  ( ( _|_ ` ( A vH B ) ) C_ ( _|_ ` ( C vH D ) ) <-> ( ( _|_ ` B ) i^i ( _|_ ` A ) ) C_ ( ( _|_ ` C ) i^i ( _|_ ` D ) ) ) | 
						
							| 23 | 17 22 | bitri |  |-  ( ( C vH D ) C_ ( A vH B ) <-> ( ( _|_ ` B ) i^i ( _|_ ` A ) ) C_ ( ( _|_ ` C ) i^i ( _|_ ` D ) ) ) | 
						
							| 24 | 14 23 | anbi12ci |  |-  ( ( A C_ ( C i^i D ) /\ ( C vH D ) C_ ( A vH B ) ) <-> ( ( ( _|_ ` B ) i^i ( _|_ ` A ) ) C_ ( ( _|_ ` C ) i^i ( _|_ ` D ) ) /\ ( ( _|_ ` C ) vH ( _|_ ` D ) ) C_ ( _|_ ` A ) ) ) | 
						
							| 25 | 2 | choccli |  |-  ( _|_ ` B ) e. CH | 
						
							| 26 | 1 | choccli |  |-  ( _|_ ` A ) e. CH | 
						
							| 27 | 3 | choccli |  |-  ( _|_ ` C ) e. CH | 
						
							| 28 | 4 | choccli |  |-  ( _|_ ` D ) e. CH | 
						
							| 29 | 25 26 27 28 | mdslmd2i |  |-  ( ( ( ( _|_ ` B ) MH ( _|_ ` A ) /\ ( _|_ ` A ) MH* ( _|_ ` B ) ) /\ ( ( ( _|_ ` B ) i^i ( _|_ ` A ) ) C_ ( ( _|_ ` C ) i^i ( _|_ ` D ) ) /\ ( ( _|_ ` C ) vH ( _|_ ` D ) ) C_ ( _|_ ` A ) ) ) -> ( ( _|_ ` C ) MH ( _|_ ` D ) <-> ( ( _|_ ` C ) vH ( _|_ ` B ) ) MH ( ( _|_ ` D ) vH ( _|_ ` B ) ) ) ) | 
						
							| 30 | 9 24 29 | syl2anb |  |-  ( ( ( A MH B /\ B MH* A ) /\ ( A C_ ( C i^i D ) /\ ( C vH D ) C_ ( A vH B ) ) ) -> ( ( _|_ ` C ) MH ( _|_ ` D ) <-> ( ( _|_ ` C ) vH ( _|_ ` B ) ) MH ( ( _|_ ` D ) vH ( _|_ ` B ) ) ) ) | 
						
							| 31 |  | dmdmd |  |-  ( ( C e. CH /\ D e. CH ) -> ( C MH* D <-> ( _|_ ` C ) MH ( _|_ ` D ) ) ) | 
						
							| 32 | 3 4 31 | mp2an |  |-  ( C MH* D <-> ( _|_ ` C ) MH ( _|_ ` D ) ) | 
						
							| 33 | 3 2 | chincli |  |-  ( C i^i B ) e. CH | 
						
							| 34 | 4 2 | chincli |  |-  ( D i^i B ) e. CH | 
						
							| 35 |  | dmdmd |  |-  ( ( ( C i^i B ) e. CH /\ ( D i^i B ) e. CH ) -> ( ( C i^i B ) MH* ( D i^i B ) <-> ( _|_ ` ( C i^i B ) ) MH ( _|_ ` ( D i^i B ) ) ) ) | 
						
							| 36 | 33 34 35 | mp2an |  |-  ( ( C i^i B ) MH* ( D i^i B ) <-> ( _|_ ` ( C i^i B ) ) MH ( _|_ ` ( D i^i B ) ) ) | 
						
							| 37 | 3 2 | chdmm1i |  |-  ( _|_ ` ( C i^i B ) ) = ( ( _|_ ` C ) vH ( _|_ ` B ) ) | 
						
							| 38 | 4 2 | chdmm1i |  |-  ( _|_ ` ( D i^i B ) ) = ( ( _|_ ` D ) vH ( _|_ ` B ) ) | 
						
							| 39 | 37 38 | breq12i |  |-  ( ( _|_ ` ( C i^i B ) ) MH ( _|_ ` ( D i^i B ) ) <-> ( ( _|_ ` C ) vH ( _|_ ` B ) ) MH ( ( _|_ ` D ) vH ( _|_ ` B ) ) ) | 
						
							| 40 | 36 39 | bitri |  |-  ( ( C i^i B ) MH* ( D i^i B ) <-> ( ( _|_ ` C ) vH ( _|_ ` B ) ) MH ( ( _|_ ` D ) vH ( _|_ ` B ) ) ) | 
						
							| 41 | 30 32 40 | 3bitr4g |  |-  ( ( ( A MH B /\ B MH* A ) /\ ( A C_ ( C i^i D ) /\ ( C vH D ) C_ ( A vH B ) ) ) -> ( C MH* D <-> ( C i^i B ) MH* ( D i^i B ) ) ) |