| 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 ) ) )  |