| Step | Hyp | Ref | Expression | 
						
							| 1 |  | eqeq1 |  |-  ( A = B -> ( A = y <-> B = y ) ) | 
						
							| 2 | 1 | biimpd |  |-  ( A = B -> ( A = y -> B = y ) ) | 
						
							| 3 | 2 | adantr |  |-  ( ( A = B /\ ( ph -> ps ) ) -> ( A = y -> B = y ) ) | 
						
							| 4 |  | simpr |  |-  ( ( A = B /\ ( ph -> ps ) ) -> ( ph -> ps ) ) | 
						
							| 5 | 3 4 | anim12d |  |-  ( ( A = B /\ ( ph -> ps ) ) -> ( ( A = y /\ ph ) -> ( B = y /\ ps ) ) ) | 
						
							| 6 | 5 | aleximi |  |-  ( A. x ( A = B /\ ( ph -> ps ) ) -> ( E. x ( A = y /\ ph ) -> E. x ( B = y /\ ps ) ) ) | 
						
							| 7 | 6 | alrimiv |  |-  ( A. x ( A = B /\ ( ph -> ps ) ) -> A. y ( E. x ( A = y /\ ph ) -> E. x ( B = y /\ ps ) ) ) | 
						
							| 8 |  | ss2ab |  |-  ( { y | E. x ( A = y /\ ph ) } C_ { y | E. x ( B = y /\ ps ) } <-> A. y ( E. x ( A = y /\ ph ) -> E. x ( B = y /\ ps ) ) ) | 
						
							| 9 | 7 8 | sylibr |  |-  ( A. x ( A = B /\ ( ph -> ps ) ) -> { y | E. x ( A = y /\ ph ) } C_ { y | E. x ( B = y /\ ps ) } ) | 
						
							| 10 |  | df-bj-gab |  |-  {{ A | x | ph }} = { y | E. x ( A = y /\ ph ) } | 
						
							| 11 |  | df-bj-gab |  |-  {{ B | x | ps }} = { y | E. x ( B = y /\ ps ) } | 
						
							| 12 | 9 10 11 | 3sstr4g |  |-  ( A. x ( A = B /\ ( ph -> ps ) ) -> {{ A | x | ph }} C_ {{ B | x | ps }} ) |