| Step | Hyp | Ref | Expression | 
						
							| 1 |  | mdslle1.1 |  |-  A e. CH | 
						
							| 2 |  | mdslle1.2 |  |-  B e. CH | 
						
							| 3 |  | mdslle1.3 |  |-  C e. CH | 
						
							| 4 |  | mdslle1.4 |  |-  D e. CH | 
						
							| 5 |  | ssrin |  |-  ( C C_ D -> ( C i^i B ) C_ ( D i^i B ) ) | 
						
							| 6 | 3 2 | chincli |  |-  ( C i^i B ) e. CH | 
						
							| 7 | 4 2 | chincli |  |-  ( D i^i B ) e. CH | 
						
							| 8 | 6 7 1 | chlej1i |  |-  ( ( C i^i B ) C_ ( D i^i B ) -> ( ( C i^i B ) vH A ) C_ ( ( D i^i B ) vH A ) ) | 
						
							| 9 |  | id |  |-  ( B MH* A -> B MH* A ) | 
						
							| 10 |  | ssin |  |-  ( ( A C_ C /\ A C_ D ) <-> A C_ ( C i^i D ) ) | 
						
							| 11 | 10 | bicomi |  |-  ( A C_ ( C i^i D ) <-> ( A C_ C /\ A C_ D ) ) | 
						
							| 12 | 11 | simplbi |  |-  ( A C_ ( C i^i D ) -> A C_ C ) | 
						
							| 13 | 1 2 | chjcli |  |-  ( A vH B ) e. CH | 
						
							| 14 | 3 4 13 | chlubi |  |-  ( ( C C_ ( A vH B ) /\ D C_ ( A vH B ) ) <-> ( C vH D ) C_ ( A vH B ) ) | 
						
							| 15 | 14 | bicomi |  |-  ( ( C vH D ) C_ ( A vH B ) <-> ( C C_ ( A vH B ) /\ D C_ ( A vH B ) ) ) | 
						
							| 16 | 15 | simplbi |  |-  ( ( C vH D ) C_ ( A vH B ) -> C C_ ( A vH B ) ) | 
						
							| 17 | 1 2 3 | 3pm3.2i |  |-  ( A e. CH /\ B e. CH /\ C e. CH ) | 
						
							| 18 |  | dmdsl3 |  |-  ( ( ( A e. CH /\ B e. CH /\ C e. CH ) /\ ( B MH* A /\ A C_ C /\ C C_ ( A vH B ) ) ) -> ( ( C i^i B ) vH A ) = C ) | 
						
							| 19 | 17 18 | mpan |  |-  ( ( B MH* A /\ A C_ C /\ C C_ ( A vH B ) ) -> ( ( C i^i B ) vH A ) = C ) | 
						
							| 20 | 9 12 16 19 | syl3an |  |-  ( ( B MH* A /\ A C_ ( C i^i D ) /\ ( C vH D ) C_ ( A vH B ) ) -> ( ( C i^i B ) vH A ) = C ) | 
						
							| 21 | 11 | simprbi |  |-  ( A C_ ( C i^i D ) -> A C_ D ) | 
						
							| 22 | 15 | simprbi |  |-  ( ( C vH D ) C_ ( A vH B ) -> D C_ ( A vH B ) ) | 
						
							| 23 | 1 2 4 | 3pm3.2i |  |-  ( A e. CH /\ B e. CH /\ D e. CH ) | 
						
							| 24 |  | dmdsl3 |  |-  ( ( ( A e. CH /\ B e. CH /\ D e. CH ) /\ ( B MH* A /\ A C_ D /\ D C_ ( A vH B ) ) ) -> ( ( D i^i B ) vH A ) = D ) | 
						
							| 25 | 23 24 | mpan |  |-  ( ( B MH* A /\ A C_ D /\ D C_ ( A vH B ) ) -> ( ( D i^i B ) vH A ) = D ) | 
						
							| 26 | 9 21 22 25 | syl3an |  |-  ( ( B MH* A /\ A C_ ( C i^i D ) /\ ( C vH D ) C_ ( A vH B ) ) -> ( ( D i^i B ) vH A ) = D ) | 
						
							| 27 | 20 26 | sseq12d |  |-  ( ( B MH* A /\ A C_ ( C i^i D ) /\ ( C vH D ) C_ ( A vH B ) ) -> ( ( ( C i^i B ) vH A ) C_ ( ( D i^i B ) vH A ) <-> C C_ D ) ) | 
						
							| 28 | 8 27 | imbitrid |  |-  ( ( B MH* A /\ A C_ ( C i^i D ) /\ ( C vH D ) C_ ( A vH B ) ) -> ( ( C i^i B ) C_ ( D i^i B ) -> C C_ D ) ) | 
						
							| 29 | 5 28 | impbid2 |  |-  ( ( B MH* A /\ A C_ ( C i^i D ) /\ ( C vH D ) C_ ( A vH B ) ) -> ( C C_ D <-> ( C i^i B ) C_ ( D i^i B ) ) ) |