| Step | 
						Hyp | 
						Ref | 
						Expression | 
					
						
							| 1 | 
							
								
							 | 
							soi.1 | 
							 |-  R Or S  | 
						
						
							| 2 | 
							
								
							 | 
							soi.2 | 
							 |-  R C_ ( S X. S )  | 
						
						
							| 3 | 
							
								2
							 | 
							brel | 
							 |-  ( A R B -> ( A e. S /\ B e. S ) )  | 
						
						
							| 4 | 
							
								3
							 | 
							simpld | 
							 |-  ( A R B -> A e. S )  | 
						
						
							| 5 | 
							
								2
							 | 
							brel | 
							 |-  ( B R C -> ( B e. S /\ C e. S ) )  | 
						
						
							| 6 | 
							
								4 5
							 | 
							anim12i | 
							 |-  ( ( A R B /\ B R C ) -> ( A e. S /\ ( B e. S /\ C e. S ) ) )  | 
						
						
							| 7 | 
							
								
							 | 
							sotr | 
							 |-  ( ( R Or S /\ ( A e. S /\ B e. S /\ C e. S ) ) -> ( ( A R B /\ B R C ) -> A R C ) )  | 
						
						
							| 8 | 
							
								1 7
							 | 
							mpan | 
							 |-  ( ( A e. S /\ B e. S /\ C e. S ) -> ( ( A R B /\ B R C ) -> A R C ) )  | 
						
						
							| 9 | 
							
								8
							 | 
							3expb | 
							 |-  ( ( A e. S /\ ( B e. S /\ C e. S ) ) -> ( ( A R B /\ B R C ) -> A R C ) )  | 
						
						
							| 10 | 
							
								6 9
							 | 
							mpcom | 
							 |-  ( ( A R B /\ B R C ) -> A R C )  |