| Step | Hyp | Ref | Expression | 
						
							| 1 |  | pi1grp.2 |  |-  G = ( J pi1 Y ) | 
						
							| 2 |  | pi1inv.n |  |-  N = ( invg ` G ) | 
						
							| 3 |  | pi1inv.j |  |-  ( ph -> J e. ( TopOn ` X ) ) | 
						
							| 4 |  | pi1inv.y |  |-  ( ph -> Y e. X ) | 
						
							| 5 |  | pi1inv.f |  |-  ( ph -> F e. ( II Cn J ) ) | 
						
							| 6 |  | pi1inv.0 |  |-  ( ph -> ( F ` 0 ) = Y ) | 
						
							| 7 |  | pi1inv.1 |  |-  ( ph -> ( F ` 1 ) = Y ) | 
						
							| 8 |  | pi1inv.i |  |-  I = ( x e. ( 0 [,] 1 ) |-> ( F ` ( 1 - x ) ) ) | 
						
							| 9 |  | eqid |  |-  ( Base ` G ) = ( Base ` G ) | 
						
							| 10 |  | eqid |  |-  ( +g ` G ) = ( +g ` G ) | 
						
							| 11 | 8 | pcorevcl |  |-  ( F e. ( II Cn J ) -> ( I e. ( II Cn J ) /\ ( I ` 0 ) = ( F ` 1 ) /\ ( I ` 1 ) = ( F ` 0 ) ) ) | 
						
							| 12 | 5 11 | syl |  |-  ( ph -> ( I e. ( II Cn J ) /\ ( I ` 0 ) = ( F ` 1 ) /\ ( I ` 1 ) = ( F ` 0 ) ) ) | 
						
							| 13 | 12 | simp1d |  |-  ( ph -> I e. ( II Cn J ) ) | 
						
							| 14 | 12 | simp2d |  |-  ( ph -> ( I ` 0 ) = ( F ` 1 ) ) | 
						
							| 15 | 14 7 | eqtrd |  |-  ( ph -> ( I ` 0 ) = Y ) | 
						
							| 16 | 12 | simp3d |  |-  ( ph -> ( I ` 1 ) = ( F ` 0 ) ) | 
						
							| 17 | 16 6 | eqtrd |  |-  ( ph -> ( I ` 1 ) = Y ) | 
						
							| 18 | 9 | a1i |  |-  ( ph -> ( Base ` G ) = ( Base ` G ) ) | 
						
							| 19 | 1 3 4 18 | pi1eluni |  |-  ( ph -> ( I e. U. ( Base ` G ) <-> ( I e. ( II Cn J ) /\ ( I ` 0 ) = Y /\ ( I ` 1 ) = Y ) ) ) | 
						
							| 20 | 13 15 17 19 | mpbir3and |  |-  ( ph -> I e. U. ( Base ` G ) ) | 
						
							| 21 | 1 3 4 18 | pi1eluni |  |-  ( ph -> ( F e. U. ( Base ` G ) <-> ( F e. ( II Cn J ) /\ ( F ` 0 ) = Y /\ ( F ` 1 ) = Y ) ) ) | 
						
							| 22 | 5 6 7 21 | mpbir3and |  |-  ( ph -> F e. U. ( Base ` G ) ) | 
						
							| 23 | 1 9 3 4 10 20 22 | pi1addval |  |-  ( ph -> ( [ I ] ( ~=ph ` J ) ( +g ` G ) [ F ] ( ~=ph ` J ) ) = [ ( I ( *p ` J ) F ) ] ( ~=ph ` J ) ) | 
						
							| 24 |  | phtpcer |  |-  ( ~=ph ` J ) Er ( II Cn J ) | 
						
							| 25 | 24 | a1i |  |-  ( ph -> ( ~=ph ` J ) Er ( II Cn J ) ) | 
						
							| 26 |  | eqid |  |-  ( ( 0 [,] 1 ) X. { ( F ` 1 ) } ) = ( ( 0 [,] 1 ) X. { ( F ` 1 ) } ) | 
						
							| 27 | 8 26 | pcorev |  |-  ( F e. ( II Cn J ) -> ( I ( *p ` J ) F ) ( ~=ph ` J ) ( ( 0 [,] 1 ) X. { ( F ` 1 ) } ) ) | 
						
							| 28 | 5 27 | syl |  |-  ( ph -> ( I ( *p ` J ) F ) ( ~=ph ` J ) ( ( 0 [,] 1 ) X. { ( F ` 1 ) } ) ) | 
						
							| 29 | 7 | sneqd |  |-  ( ph -> { ( F ` 1 ) } = { Y } ) | 
						
							| 30 | 29 | xpeq2d |  |-  ( ph -> ( ( 0 [,] 1 ) X. { ( F ` 1 ) } ) = ( ( 0 [,] 1 ) X. { Y } ) ) | 
						
							| 31 | 28 30 | breqtrd |  |-  ( ph -> ( I ( *p ` J ) F ) ( ~=ph ` J ) ( ( 0 [,] 1 ) X. { Y } ) ) | 
						
							| 32 | 25 31 | erthi |  |-  ( ph -> [ ( I ( *p ` J ) F ) ] ( ~=ph ` J ) = [ ( ( 0 [,] 1 ) X. { Y } ) ] ( ~=ph ` J ) ) | 
						
							| 33 |  | eqid |  |-  ( ( 0 [,] 1 ) X. { Y } ) = ( ( 0 [,] 1 ) X. { Y } ) | 
						
							| 34 | 1 9 3 4 33 | pi1grplem |  |-  ( ph -> ( G e. Grp /\ [ ( ( 0 [,] 1 ) X. { Y } ) ] ( ~=ph ` J ) = ( 0g ` G ) ) ) | 
						
							| 35 | 34 | simprd |  |-  ( ph -> [ ( ( 0 [,] 1 ) X. { Y } ) ] ( ~=ph ` J ) = ( 0g ` G ) ) | 
						
							| 36 | 23 32 35 | 3eqtrd |  |-  ( ph -> ( [ I ] ( ~=ph ` J ) ( +g ` G ) [ F ] ( ~=ph ` J ) ) = ( 0g ` G ) ) | 
						
							| 37 | 34 | simpld |  |-  ( ph -> G e. Grp ) | 
						
							| 38 | 1 9 3 4 5 6 7 | elpi1i |  |-  ( ph -> [ F ] ( ~=ph ` J ) e. ( Base ` G ) ) | 
						
							| 39 | 1 9 3 4 13 15 17 | elpi1i |  |-  ( ph -> [ I ] ( ~=ph ` J ) e. ( Base ` G ) ) | 
						
							| 40 |  | eqid |  |-  ( 0g ` G ) = ( 0g ` G ) | 
						
							| 41 | 9 10 40 2 | grpinvid2 |  |-  ( ( G e. Grp /\ [ F ] ( ~=ph ` J ) e. ( Base ` G ) /\ [ I ] ( ~=ph ` J ) e. ( Base ` G ) ) -> ( ( N ` [ F ] ( ~=ph ` J ) ) = [ I ] ( ~=ph ` J ) <-> ( [ I ] ( ~=ph ` J ) ( +g ` G ) [ F ] ( ~=ph ` J ) ) = ( 0g ` G ) ) ) | 
						
							| 42 | 37 38 39 41 | syl3anc |  |-  ( ph -> ( ( N ` [ F ] ( ~=ph ` J ) ) = [ I ] ( ~=ph ` J ) <-> ( [ I ] ( ~=ph ` J ) ( +g ` G ) [ F ] ( ~=ph ` J ) ) = ( 0g ` G ) ) ) | 
						
							| 43 | 36 42 | mpbird |  |-  ( ph -> ( N ` [ F ] ( ~=ph ` J ) ) = [ I ] ( ~=ph ` J ) ) |