| 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 | 3 4 1 | chlej1i |  |-  ( C C_ D -> ( C vH A ) C_ ( D vH A ) ) | 
						
							| 6 |  | ssrin |  |-  ( ( C vH A ) C_ ( D vH A ) -> ( ( C vH A ) i^i B ) C_ ( ( D vH A ) i^i B ) ) | 
						
							| 7 |  | id |  |-  ( A MH B -> A MH B ) | 
						
							| 8 |  | ssin |  |-  ( ( ( A i^i B ) C_ C /\ ( A i^i B ) C_ D ) <-> ( A i^i B ) C_ ( C i^i D ) ) | 
						
							| 9 | 8 | bicomi |  |-  ( ( A i^i B ) C_ ( C i^i D ) <-> ( ( A i^i B ) C_ C /\ ( A i^i B ) C_ D ) ) | 
						
							| 10 | 9 | simplbi |  |-  ( ( A i^i B ) C_ ( C i^i D ) -> ( A i^i B ) C_ C ) | 
						
							| 11 | 3 4 2 | chlubi |  |-  ( ( C C_ B /\ D C_ B ) <-> ( C vH D ) C_ B ) | 
						
							| 12 | 11 | bicomi |  |-  ( ( C vH D ) C_ B <-> ( C C_ B /\ D C_ B ) ) | 
						
							| 13 | 12 | simplbi |  |-  ( ( C vH D ) C_ B -> C C_ B ) | 
						
							| 14 | 1 2 3 | 3pm3.2i |  |-  ( A e. CH /\ B e. CH /\ C e. CH ) | 
						
							| 15 |  | mdsl3 |  |-  ( ( ( A e. CH /\ B e. CH /\ C e. CH ) /\ ( A MH B /\ ( A i^i B ) C_ C /\ C C_ B ) ) -> ( ( C vH A ) i^i B ) = C ) | 
						
							| 16 | 14 15 | mpan |  |-  ( ( A MH B /\ ( A i^i B ) C_ C /\ C C_ B ) -> ( ( C vH A ) i^i B ) = C ) | 
						
							| 17 | 7 10 13 16 | syl3an |  |-  ( ( A MH B /\ ( A i^i B ) C_ ( C i^i D ) /\ ( C vH D ) C_ B ) -> ( ( C vH A ) i^i B ) = C ) | 
						
							| 18 | 9 | simprbi |  |-  ( ( A i^i B ) C_ ( C i^i D ) -> ( A i^i B ) C_ D ) | 
						
							| 19 | 12 | simprbi |  |-  ( ( C vH D ) C_ B -> D C_ B ) | 
						
							| 20 | 1 2 4 | 3pm3.2i |  |-  ( A e. CH /\ B e. CH /\ D e. CH ) | 
						
							| 21 |  | mdsl3 |  |-  ( ( ( A e. CH /\ B e. CH /\ D e. CH ) /\ ( A MH B /\ ( A i^i B ) C_ D /\ D C_ B ) ) -> ( ( D vH A ) i^i B ) = D ) | 
						
							| 22 | 20 21 | mpan |  |-  ( ( A MH B /\ ( A i^i B ) C_ D /\ D C_ B ) -> ( ( D vH A ) i^i B ) = D ) | 
						
							| 23 | 7 18 19 22 | syl3an |  |-  ( ( A MH B /\ ( A i^i B ) C_ ( C i^i D ) /\ ( C vH D ) C_ B ) -> ( ( D vH A ) i^i B ) = D ) | 
						
							| 24 | 17 23 | sseq12d |  |-  ( ( A MH B /\ ( A i^i B ) C_ ( C i^i D ) /\ ( C vH D ) C_ B ) -> ( ( ( C vH A ) i^i B ) C_ ( ( D vH A ) i^i B ) <-> C C_ D ) ) | 
						
							| 25 | 6 24 | imbitrid |  |-  ( ( A MH B /\ ( A i^i B ) C_ ( C i^i D ) /\ ( C vH D ) C_ B ) -> ( ( C vH A ) C_ ( D vH A ) -> C C_ D ) ) | 
						
							| 26 | 5 25 | impbid2 |  |-  ( ( A MH B /\ ( A i^i B ) C_ ( C i^i D ) /\ ( C vH D ) C_ B ) -> ( C C_ D <-> ( C vH A ) C_ ( D vH A ) ) ) |