| Step | Hyp | Ref | Expression | 
						
							| 1 |  | idn1 |  |-  (. ( ( ph /\ ps /\ ch ) -> th ) ->. ( ( ph /\ ps /\ ch ) -> th ) ). | 
						
							| 2 |  | df-3an |  |-  ( ( ph /\ ps /\ ch ) <-> ( ( ph /\ ps ) /\ ch ) ) | 
						
							| 3 |  | imbi1 |  |-  ( ( ( ph /\ ps /\ ch ) <-> ( ( ph /\ ps ) /\ ch ) ) -> ( ( ( ph /\ ps /\ ch ) -> th ) <-> ( ( ( ph /\ ps ) /\ ch ) -> th ) ) ) | 
						
							| 4 | 3 | biimpcd |  |-  ( ( ( ph /\ ps /\ ch ) -> th ) -> ( ( ( ph /\ ps /\ ch ) <-> ( ( ph /\ ps ) /\ ch ) ) -> ( ( ( ph /\ ps ) /\ ch ) -> th ) ) ) | 
						
							| 5 | 1 2 4 | e10 |  |-  (. ( ( ph /\ ps /\ ch ) -> th ) ->. ( ( ( ph /\ ps ) /\ ch ) -> th ) ). | 
						
							| 6 |  | pm3.3 |  |-  ( ( ( ( ph /\ ps ) /\ ch ) -> th ) -> ( ( ph /\ ps ) -> ( ch -> th ) ) ) | 
						
							| 7 | 5 6 | e1a |  |-  (. ( ( ph /\ ps /\ ch ) -> th ) ->. ( ( ph /\ ps ) -> ( ch -> th ) ) ). | 
						
							| 8 |  | pm3.3 |  |-  ( ( ( ph /\ ps ) -> ( ch -> th ) ) -> ( ph -> ( ps -> ( ch -> th ) ) ) ) | 
						
							| 9 | 7 8 | e1a |  |-  (. ( ( ph /\ ps /\ ch ) -> th ) ->. ( ph -> ( ps -> ( ch -> th ) ) ) ). | 
						
							| 10 | 9 | in1 |  |-  ( ( ( ph /\ ps /\ ch ) -> th ) -> ( ph -> ( ps -> ( ch -> th ) ) ) ) | 
						
							| 11 |  | idn1 |  |-  (. ( ph -> ( ps -> ( ch -> th ) ) ) ->. ( ph -> ( ps -> ( ch -> th ) ) ) ). | 
						
							| 12 |  | pm3.31 |  |-  ( ( ph -> ( ps -> ( ch -> th ) ) ) -> ( ( ph /\ ps ) -> ( ch -> th ) ) ) | 
						
							| 13 | 11 12 | e1a |  |-  (. ( ph -> ( ps -> ( ch -> th ) ) ) ->. ( ( ph /\ ps ) -> ( ch -> th ) ) ). | 
						
							| 14 |  | pm3.31 |  |-  ( ( ( ph /\ ps ) -> ( ch -> th ) ) -> ( ( ( ph /\ ps ) /\ ch ) -> th ) ) | 
						
							| 15 | 13 14 | e1a |  |-  (. ( ph -> ( ps -> ( ch -> th ) ) ) ->. ( ( ( ph /\ ps ) /\ ch ) -> th ) ). | 
						
							| 16 | 3 | biimprd |  |-  ( ( ( ph /\ ps /\ ch ) <-> ( ( ph /\ ps ) /\ ch ) ) -> ( ( ( ( ph /\ ps ) /\ ch ) -> th ) -> ( ( ph /\ ps /\ ch ) -> th ) ) ) | 
						
							| 17 | 2 15 16 | e01 |  |-  (. ( ph -> ( ps -> ( ch -> th ) ) ) ->. ( ( ph /\ ps /\ ch ) -> th ) ). | 
						
							| 18 | 17 | in1 |  |-  ( ( ph -> ( ps -> ( ch -> th ) ) ) -> ( ( ph /\ ps /\ ch ) -> th ) ) | 
						
							| 19 |  | impbi |  |-  ( ( ( ( ph /\ ps /\ ch ) -> th ) -> ( ph -> ( ps -> ( ch -> th ) ) ) ) -> ( ( ( ph -> ( ps -> ( ch -> th ) ) ) -> ( ( ph /\ ps /\ ch ) -> th ) ) -> ( ( ( ph /\ ps /\ ch ) -> th ) <-> ( ph -> ( ps -> ( ch -> th ) ) ) ) ) ) | 
						
							| 20 | 10 18 19 | e00 |  |-  ( ( ( ph /\ ps /\ ch ) -> th ) <-> ( ph -> ( ps -> ( ch -> th ) ) ) ) |