| Step | Hyp | Ref | Expression | 
						
							| 1 |  | honegdi |  |-  ( ( T : ~H --> ~H /\ U : ~H --> ~H ) -> ( -u 1 .op ( T +op U ) ) = ( ( -u 1 .op T ) +op ( -u 1 .op U ) ) ) | 
						
							| 2 | 1 | adantl |  |-  ( ( ( R : ~H --> ~H /\ S : ~H --> ~H ) /\ ( T : ~H --> ~H /\ U : ~H --> ~H ) ) -> ( -u 1 .op ( T +op U ) ) = ( ( -u 1 .op T ) +op ( -u 1 .op U ) ) ) | 
						
							| 3 | 2 | oveq2d |  |-  ( ( ( R : ~H --> ~H /\ S : ~H --> ~H ) /\ ( T : ~H --> ~H /\ U : ~H --> ~H ) ) -> ( ( R +op S ) +op ( -u 1 .op ( T +op U ) ) ) = ( ( R +op S ) +op ( ( -u 1 .op T ) +op ( -u 1 .op U ) ) ) ) | 
						
							| 4 |  | neg1cn |  |-  -u 1 e. CC | 
						
							| 5 |  | homulcl |  |-  ( ( -u 1 e. CC /\ T : ~H --> ~H ) -> ( -u 1 .op T ) : ~H --> ~H ) | 
						
							| 6 | 4 5 | mpan |  |-  ( T : ~H --> ~H -> ( -u 1 .op T ) : ~H --> ~H ) | 
						
							| 7 |  | homulcl |  |-  ( ( -u 1 e. CC /\ U : ~H --> ~H ) -> ( -u 1 .op U ) : ~H --> ~H ) | 
						
							| 8 | 4 7 | mpan |  |-  ( U : ~H --> ~H -> ( -u 1 .op U ) : ~H --> ~H ) | 
						
							| 9 | 6 8 | anim12i |  |-  ( ( T : ~H --> ~H /\ U : ~H --> ~H ) -> ( ( -u 1 .op T ) : ~H --> ~H /\ ( -u 1 .op U ) : ~H --> ~H ) ) | 
						
							| 10 |  | hoadd4 |  |-  ( ( ( R : ~H --> ~H /\ S : ~H --> ~H ) /\ ( ( -u 1 .op T ) : ~H --> ~H /\ ( -u 1 .op U ) : ~H --> ~H ) ) -> ( ( R +op S ) +op ( ( -u 1 .op T ) +op ( -u 1 .op U ) ) ) = ( ( R +op ( -u 1 .op T ) ) +op ( S +op ( -u 1 .op U ) ) ) ) | 
						
							| 11 | 9 10 | sylan2 |  |-  ( ( ( R : ~H --> ~H /\ S : ~H --> ~H ) /\ ( T : ~H --> ~H /\ U : ~H --> ~H ) ) -> ( ( R +op S ) +op ( ( -u 1 .op T ) +op ( -u 1 .op U ) ) ) = ( ( R +op ( -u 1 .op T ) ) +op ( S +op ( -u 1 .op U ) ) ) ) | 
						
							| 12 | 3 11 | eqtrd |  |-  ( ( ( R : ~H --> ~H /\ S : ~H --> ~H ) /\ ( T : ~H --> ~H /\ U : ~H --> ~H ) ) -> ( ( R +op S ) +op ( -u 1 .op ( T +op U ) ) ) = ( ( R +op ( -u 1 .op T ) ) +op ( S +op ( -u 1 .op U ) ) ) ) | 
						
							| 13 |  | hoaddcl |  |-  ( ( R : ~H --> ~H /\ S : ~H --> ~H ) -> ( R +op S ) : ~H --> ~H ) | 
						
							| 14 |  | hoaddcl |  |-  ( ( T : ~H --> ~H /\ U : ~H --> ~H ) -> ( T +op U ) : ~H --> ~H ) | 
						
							| 15 |  | honegsub |  |-  ( ( ( R +op S ) : ~H --> ~H /\ ( T +op U ) : ~H --> ~H ) -> ( ( R +op S ) +op ( -u 1 .op ( T +op U ) ) ) = ( ( R +op S ) -op ( T +op U ) ) ) | 
						
							| 16 | 13 14 15 | syl2an |  |-  ( ( ( R : ~H --> ~H /\ S : ~H --> ~H ) /\ ( T : ~H --> ~H /\ U : ~H --> ~H ) ) -> ( ( R +op S ) +op ( -u 1 .op ( T +op U ) ) ) = ( ( R +op S ) -op ( T +op U ) ) ) | 
						
							| 17 |  | honegsub |  |-  ( ( R : ~H --> ~H /\ T : ~H --> ~H ) -> ( R +op ( -u 1 .op T ) ) = ( R -op T ) ) | 
						
							| 18 | 17 | ad2ant2r |  |-  ( ( ( R : ~H --> ~H /\ S : ~H --> ~H ) /\ ( T : ~H --> ~H /\ U : ~H --> ~H ) ) -> ( R +op ( -u 1 .op T ) ) = ( R -op T ) ) | 
						
							| 19 |  | honegsub |  |-  ( ( S : ~H --> ~H /\ U : ~H --> ~H ) -> ( S +op ( -u 1 .op U ) ) = ( S -op U ) ) | 
						
							| 20 | 19 | ad2ant2l |  |-  ( ( ( R : ~H --> ~H /\ S : ~H --> ~H ) /\ ( T : ~H --> ~H /\ U : ~H --> ~H ) ) -> ( S +op ( -u 1 .op U ) ) = ( S -op U ) ) | 
						
							| 21 | 18 20 | oveq12d |  |-  ( ( ( R : ~H --> ~H /\ S : ~H --> ~H ) /\ ( T : ~H --> ~H /\ U : ~H --> ~H ) ) -> ( ( R +op ( -u 1 .op T ) ) +op ( S +op ( -u 1 .op U ) ) ) = ( ( R -op T ) +op ( S -op U ) ) ) | 
						
							| 22 | 12 16 21 | 3eqtr3d |  |-  ( ( ( R : ~H --> ~H /\ S : ~H --> ~H ) /\ ( T : ~H --> ~H /\ U : ~H --> ~H ) ) -> ( ( R +op S ) -op ( T +op U ) ) = ( ( R -op T ) +op ( S -op U ) ) ) |