| Step | Hyp | Ref | Expression | 
						
							| 1 |  | isleag.p |  |-  P = ( Base ` G ) | 
						
							| 2 |  | isleag.g |  |-  ( ph -> G e. TarskiG ) | 
						
							| 3 |  | isleag.a |  |-  ( ph -> A e. P ) | 
						
							| 4 |  | isleag.b |  |-  ( ph -> B e. P ) | 
						
							| 5 |  | isleag.c |  |-  ( ph -> C e. P ) | 
						
							| 6 |  | isleag.d |  |-  ( ph -> D e. P ) | 
						
							| 7 |  | isleag.e |  |-  ( ph -> E e. P ) | 
						
							| 8 |  | isleag.f |  |-  ( ph -> F e. P ) | 
						
							| 9 |  | isleagd.s |  |-  .<_ = ( leA ` G ) | 
						
							| 10 |  | isleagd.x |  |-  ( ph -> X e. P ) | 
						
							| 11 |  | isleagd.1 |  |-  ( ph -> X ( inA ` G ) <" D E F "> ) | 
						
							| 12 |  | isleagd.2 |  |-  ( ph -> <" A B C "> ( cgrA ` G ) <" D E X "> ) | 
						
							| 13 | 9 | eqcomi |  |-  ( leA ` G ) = .<_ | 
						
							| 14 | 13 | a1i |  |-  ( ph -> ( leA ` G ) = .<_ ) | 
						
							| 15 |  | simpr |  |-  ( ( ph /\ x = X ) -> x = X ) | 
						
							| 16 | 15 | breq1d |  |-  ( ( ph /\ x = X ) -> ( x ( inA ` G ) <" D E F "> <-> X ( inA ` G ) <" D E F "> ) ) | 
						
							| 17 |  | eqidd |  |-  ( ( ph /\ x = X ) -> D = D ) | 
						
							| 18 |  | eqidd |  |-  ( ( ph /\ x = X ) -> E = E ) | 
						
							| 19 | 17 18 15 | s3eqd |  |-  ( ( ph /\ x = X ) -> <" D E x "> = <" D E X "> ) | 
						
							| 20 | 19 | breq2d |  |-  ( ( ph /\ x = X ) -> ( <" A B C "> ( cgrA ` G ) <" D E x "> <-> <" A B C "> ( cgrA ` G ) <" D E X "> ) ) | 
						
							| 21 | 16 20 | anbi12d |  |-  ( ( ph /\ x = X ) -> ( ( x ( inA ` G ) <" D E F "> /\ <" A B C "> ( cgrA ` G ) <" D E x "> ) <-> ( X ( inA ` G ) <" D E F "> /\ <" A B C "> ( cgrA ` G ) <" D E X "> ) ) ) | 
						
							| 22 | 11 12 | jca |  |-  ( ph -> ( X ( inA ` G ) <" D E F "> /\ <" A B C "> ( cgrA ` G ) <" D E X "> ) ) | 
						
							| 23 | 10 21 22 | rspcedvd |  |-  ( ph -> E. x e. P ( x ( inA ` G ) <" D E F "> /\ <" A B C "> ( cgrA ` G ) <" D E x "> ) ) | 
						
							| 24 | 1 2 3 4 5 6 7 8 | isleag |  |-  ( ph -> ( <" A B C "> ( leA ` G ) <" D E F "> <-> E. x e. P ( x ( inA ` G ) <" D E F "> /\ <" A B C "> ( cgrA ` G ) <" D E x "> ) ) ) | 
						
							| 25 | 23 24 | mpbird |  |-  ( ph -> <" A B C "> ( leA ` G ) <" D E F "> ) | 
						
							| 26 | 14 25 | breqdi |  |-  ( ph -> <" A B C "> .<_ <" D E F "> ) |