| Step | 
						Hyp | 
						Ref | 
						Expression | 
					
						
							| 1 | 
							
								
							 | 
							pclss.a | 
							 |-  A = ( Atoms ` K )  | 
						
						
							| 2 | 
							
								
							 | 
							pclss.c | 
							 |-  U = ( PCl ` K )  | 
						
						
							| 3 | 
							
								
							 | 
							sstr2 | 
							 |-  ( X C_ Y -> ( Y C_ y -> X C_ y ) )  | 
						
						
							| 4 | 
							
								3
							 | 
							3ad2ant2 | 
							 |-  ( ( K e. V /\ X C_ Y /\ Y C_ A ) -> ( Y C_ y -> X C_ y ) )  | 
						
						
							| 5 | 
							
								4
							 | 
							adantr | 
							 |-  ( ( ( K e. V /\ X C_ Y /\ Y C_ A ) /\ y e. ( PSubSp ` K ) ) -> ( Y C_ y -> X C_ y ) )  | 
						
						
							| 6 | 
							
								5
							 | 
							ss2rabdv | 
							 |-  ( ( K e. V /\ X C_ Y /\ Y C_ A ) -> { y e. ( PSubSp ` K ) | Y C_ y } C_ { y e. ( PSubSp ` K ) | X C_ y } ) | 
						
						
							| 7 | 
							
								
							 | 
							intss | 
							 |-  ( { y e. ( PSubSp ` K ) | Y C_ y } C_ { y e. ( PSubSp ` K ) | X C_ y } -> |^| { y e. ( PSubSp ` K ) | X C_ y } C_ |^| { y e. ( PSubSp ` K ) | Y C_ y } ) | 
						
						
							| 8 | 
							
								6 7
							 | 
							syl | 
							 |-  ( ( K e. V /\ X C_ Y /\ Y C_ A ) -> |^| { y e. ( PSubSp ` K ) | X C_ y } C_ |^| { y e. ( PSubSp ` K ) | Y C_ y } ) | 
						
						
							| 9 | 
							
								
							 | 
							simp1 | 
							 |-  ( ( K e. V /\ X C_ Y /\ Y C_ A ) -> K e. V )  | 
						
						
							| 10 | 
							
								
							 | 
							sstr | 
							 |-  ( ( X C_ Y /\ Y C_ A ) -> X C_ A )  | 
						
						
							| 11 | 
							
								10
							 | 
							3adant1 | 
							 |-  ( ( K e. V /\ X C_ Y /\ Y C_ A ) -> X C_ A )  | 
						
						
							| 12 | 
							
								
							 | 
							eqid | 
							 |-  ( PSubSp ` K ) = ( PSubSp ` K )  | 
						
						
							| 13 | 
							
								1 12 2
							 | 
							pclvalN | 
							 |-  ( ( K e. V /\ X C_ A ) -> ( U ` X ) = |^| { y e. ( PSubSp ` K ) | X C_ y } ) | 
						
						
							| 14 | 
							
								9 11 13
							 | 
							syl2anc | 
							 |-  ( ( K e. V /\ X C_ Y /\ Y C_ A ) -> ( U ` X ) = |^| { y e. ( PSubSp ` K ) | X C_ y } ) | 
						
						
							| 15 | 
							
								1 12 2
							 | 
							pclvalN | 
							 |-  ( ( K e. V /\ Y C_ A ) -> ( U ` Y ) = |^| { y e. ( PSubSp ` K ) | Y C_ y } ) | 
						
						
							| 16 | 
							
								15
							 | 
							3adant2 | 
							 |-  ( ( K e. V /\ X C_ Y /\ Y C_ A ) -> ( U ` Y ) = |^| { y e. ( PSubSp ` K ) | Y C_ y } ) | 
						
						
							| 17 | 
							
								8 14 16
							 | 
							3sstr4d | 
							 |-  ( ( K e. V /\ X C_ Y /\ Y C_ A ) -> ( U ` X ) C_ ( U ` Y ) )  |