| 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 ) ) )  |