| Step | Hyp | Ref | Expression | 
						
							| 1 |  | erngset.h-r |  |-  H = ( LHyp ` K ) | 
						
							| 2 |  | erngset.t-r |  |-  T = ( ( LTrn ` K ) ` W ) | 
						
							| 3 |  | erngset.e-r |  |-  E = ( ( TEndo ` K ) ` W ) | 
						
							| 4 |  | erngset.d-r |  |-  D = ( ( EDRingR ` K ) ` W ) | 
						
							| 5 |  | erng.p-r |  |-  .+ = ( +g ` D ) | 
						
							| 6 | 1 2 3 4 5 | erngplus-rN |  |-  ( ( ( K e. HL /\ W e. H ) /\ ( U e. E /\ V e. E ) ) -> ( U .+ V ) = ( f e. T |-> ( ( U ` f ) o. ( V ` f ) ) ) ) | 
						
							| 7 | 6 | 3adantr3 |  |-  ( ( ( K e. HL /\ W e. H ) /\ ( U e. E /\ V e. E /\ F e. T ) ) -> ( U .+ V ) = ( f e. T |-> ( ( U ` f ) o. ( V ` f ) ) ) ) | 
						
							| 8 |  | fveq2 |  |-  ( f = F -> ( U ` f ) = ( U ` F ) ) | 
						
							| 9 |  | fveq2 |  |-  ( f = F -> ( V ` f ) = ( V ` F ) ) | 
						
							| 10 | 8 9 | coeq12d |  |-  ( f = F -> ( ( U ` f ) o. ( V ` f ) ) = ( ( U ` F ) o. ( V ` F ) ) ) | 
						
							| 11 | 10 | adantl |  |-  ( ( ( ( K e. HL /\ W e. H ) /\ ( U e. E /\ V e. E /\ F e. T ) ) /\ f = F ) -> ( ( U ` f ) o. ( V ` f ) ) = ( ( U ` F ) o. ( V ` F ) ) ) | 
						
							| 12 |  | simpr3 |  |-  ( ( ( K e. HL /\ W e. H ) /\ ( U e. E /\ V e. E /\ F e. T ) ) -> F e. T ) | 
						
							| 13 |  | fvex |  |-  ( U ` F ) e. _V | 
						
							| 14 |  | fvex |  |-  ( V ` F ) e. _V | 
						
							| 15 | 13 14 | coex |  |-  ( ( U ` F ) o. ( V ` F ) ) e. _V | 
						
							| 16 | 15 | a1i |  |-  ( ( ( K e. HL /\ W e. H ) /\ ( U e. E /\ V e. E /\ F e. T ) ) -> ( ( U ` F ) o. ( V ` F ) ) e. _V ) | 
						
							| 17 | 7 11 12 16 | fvmptd |  |-  ( ( ( K e. HL /\ W e. H ) /\ ( U e. E /\ V e. E /\ F e. T ) ) -> ( ( U .+ V ) ` F ) = ( ( U ` F ) o. ( V ` F ) ) ) |