| Step | Hyp | Ref | Expression | 
						
							| 1 |  | ercpbl.r |  |-  ( ph -> .~ Er V ) | 
						
							| 2 |  | ercpbl.v |  |-  ( ph -> V e. W ) | 
						
							| 3 |  | ercpbl.f |  |-  F = ( x e. V |-> [ x ] .~ ) | 
						
							| 4 |  | ercpbl.c |  |-  ( ( ph /\ ( a e. V /\ b e. V ) ) -> ( a .+ b ) e. V ) | 
						
							| 5 |  | ercpbl.e |  |-  ( ph -> ( ( A .~ C /\ B .~ D ) -> ( A .+ B ) .~ ( C .+ D ) ) ) | 
						
							| 6 | 5 | 3ad2ant1 |  |-  ( ( ph /\ ( A e. V /\ B e. V ) /\ ( C e. V /\ D e. V ) ) -> ( ( A .~ C /\ B .~ D ) -> ( A .+ B ) .~ ( C .+ D ) ) ) | 
						
							| 7 | 1 | 3ad2ant1 |  |-  ( ( ph /\ ( A e. V /\ B e. V ) /\ ( C e. V /\ D e. V ) ) -> .~ Er V ) | 
						
							| 8 | 2 | 3ad2ant1 |  |-  ( ( ph /\ ( A e. V /\ B e. V ) /\ ( C e. V /\ D e. V ) ) -> V e. W ) | 
						
							| 9 |  | simp2l |  |-  ( ( ph /\ ( A e. V /\ B e. V ) /\ ( C e. V /\ D e. V ) ) -> A e. V ) | 
						
							| 10 | 7 8 3 9 | ercpbllem |  |-  ( ( ph /\ ( A e. V /\ B e. V ) /\ ( C e. V /\ D e. V ) ) -> ( ( F ` A ) = ( F ` C ) <-> A .~ C ) ) | 
						
							| 11 |  | simp2r |  |-  ( ( ph /\ ( A e. V /\ B e. V ) /\ ( C e. V /\ D e. V ) ) -> B e. V ) | 
						
							| 12 | 7 8 3 11 | ercpbllem |  |-  ( ( ph /\ ( A e. V /\ B e. V ) /\ ( C e. V /\ D e. V ) ) -> ( ( F ` B ) = ( F ` D ) <-> B .~ D ) ) | 
						
							| 13 | 10 12 | anbi12d |  |-  ( ( ph /\ ( A e. V /\ B e. V ) /\ ( C e. V /\ D e. V ) ) -> ( ( ( F ` A ) = ( F ` C ) /\ ( F ` B ) = ( F ` D ) ) <-> ( A .~ C /\ B .~ D ) ) ) | 
						
							| 14 | 4 | caovclg |  |-  ( ( ph /\ ( A e. V /\ B e. V ) ) -> ( A .+ B ) e. V ) | 
						
							| 15 | 14 | 3adant3 |  |-  ( ( ph /\ ( A e. V /\ B e. V ) /\ ( C e. V /\ D e. V ) ) -> ( A .+ B ) e. V ) | 
						
							| 16 | 7 8 3 15 | ercpbllem |  |-  ( ( ph /\ ( A e. V /\ B e. V ) /\ ( C e. V /\ D e. V ) ) -> ( ( F ` ( A .+ B ) ) = ( F ` ( C .+ D ) ) <-> ( A .+ B ) .~ ( C .+ D ) ) ) | 
						
							| 17 | 6 13 16 | 3imtr4d |  |-  ( ( ph /\ ( A e. V /\ B e. V ) /\ ( C e. V /\ D e. V ) ) -> ( ( ( F ` A ) = ( F ` C ) /\ ( F ` B ) = ( F ` D ) ) -> ( F ` ( A .+ B ) ) = ( F ` ( C .+ D ) ) ) ) |