| Step | Hyp | Ref | Expression | 
						
							| 1 |  | sbcimg |  |-  ( A e. V -> ( [. A / x ]. ( ph -> ( ps -> ch ) ) <-> ( [. A / x ]. ph -> [. A / x ]. ( ps -> ch ) ) ) ) | 
						
							| 2 | 1 | biimpd |  |-  ( A e. V -> ( [. A / x ]. ( ph -> ( ps -> ch ) ) -> ( [. A / x ]. ph -> [. A / x ]. ( ps -> ch ) ) ) ) | 
						
							| 3 |  | sbcimg |  |-  ( A e. V -> ( [. A / x ]. ( ps -> ch ) <-> ( [. A / x ]. ps -> [. A / x ]. ch ) ) ) | 
						
							| 4 |  | imbi2 |  |-  ( ( [. A / x ]. ( ps -> ch ) <-> ( [. A / x ]. ps -> [. A / x ]. ch ) ) -> ( ( [. A / x ]. ph -> [. A / x ]. ( ps -> ch ) ) <-> ( [. A / x ]. ph -> ( [. A / x ]. ps -> [. A / x ]. ch ) ) ) ) | 
						
							| 5 | 4 | biimpcd |  |-  ( ( [. A / x ]. ph -> [. A / x ]. ( ps -> ch ) ) -> ( ( [. A / x ]. ( ps -> ch ) <-> ( [. A / x ]. ps -> [. A / x ]. ch ) ) -> ( [. A / x ]. ph -> ( [. A / x ]. ps -> [. A / x ]. ch ) ) ) ) | 
						
							| 6 | 2 3 5 | syl6ci |  |-  ( A e. V -> ( [. A / x ]. ( ph -> ( ps -> ch ) ) -> ( [. A / x ]. ph -> ( [. A / x ]. ps -> [. A / x ]. ch ) ) ) ) | 
						
							| 7 |  | idd |  |-  ( A e. V -> ( ( [. A / x ]. ph -> ( [. A / x ]. ps -> [. A / x ]. ch ) ) -> ( [. A / x ]. ph -> ( [. A / x ]. ps -> [. A / x ]. ch ) ) ) ) | 
						
							| 8 |  | biimpr |  |-  ( ( [. A / x ]. ( ps -> ch ) <-> ( [. A / x ]. ps -> [. A / x ]. ch ) ) -> ( ( [. A / x ]. ps -> [. A / x ]. ch ) -> [. A / x ]. ( ps -> ch ) ) ) | 
						
							| 9 | 3 7 8 | ee13 |  |-  ( A e. V -> ( ( [. A / x ]. ph -> ( [. A / x ]. ps -> [. A / x ]. ch ) ) -> ( [. A / x ]. ph -> [. A / x ]. ( ps -> ch ) ) ) ) | 
						
							| 10 | 9 1 | sylibrd |  |-  ( A e. V -> ( ( [. A / x ]. ph -> ( [. A / x ]. ps -> [. A / x ]. ch ) ) -> [. A / x ]. ( ph -> ( ps -> ch ) ) ) ) | 
						
							| 11 | 6 10 | impbid |  |-  ( A e. V -> ( [. A / x ]. ( ph -> ( ps -> ch ) ) <-> ( [. A / x ]. ph -> ( [. A / x ]. ps -> [. A / x ]. ch ) ) ) ) |