| 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 | erngfplus-rN | ⊢ ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  →   +   =  ( 𝑠  ∈  𝐸 ,  𝑡  ∈  𝐸  ↦  ( 𝑔  ∈  𝑇  ↦  ( ( 𝑠 ‘ 𝑔 )  ∘  ( 𝑡 ‘ 𝑔 ) ) ) ) ) | 
						
							| 7 | 6 | oveqd | ⊢ ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  →  ( 𝑈  +  𝑉 )  =  ( 𝑈 ( 𝑠  ∈  𝐸 ,  𝑡  ∈  𝐸  ↦  ( 𝑔  ∈  𝑇  ↦  ( ( 𝑠 ‘ 𝑔 )  ∘  ( 𝑡 ‘ 𝑔 ) ) ) ) 𝑉 ) ) | 
						
							| 8 |  | eqid | ⊢ ( 𝑠  ∈  𝐸 ,  𝑡  ∈  𝐸  ↦  ( 𝑔  ∈  𝑇  ↦  ( ( 𝑠 ‘ 𝑔 )  ∘  ( 𝑡 ‘ 𝑔 ) ) ) )  =  ( 𝑠  ∈  𝐸 ,  𝑡  ∈  𝐸  ↦  ( 𝑔  ∈  𝑇  ↦  ( ( 𝑠 ‘ 𝑔 )  ∘  ( 𝑡 ‘ 𝑔 ) ) ) ) | 
						
							| 9 | 8 2 | tendopl | ⊢ ( ( 𝑈  ∈  𝐸  ∧  𝑉  ∈  𝐸 )  →  ( 𝑈 ( 𝑠  ∈  𝐸 ,  𝑡  ∈  𝐸  ↦  ( 𝑔  ∈  𝑇  ↦  ( ( 𝑠 ‘ 𝑔 )  ∘  ( 𝑡 ‘ 𝑔 ) ) ) ) 𝑉 )  =  ( 𝑓  ∈  𝑇  ↦  ( ( 𝑈 ‘ 𝑓 )  ∘  ( 𝑉 ‘ 𝑓 ) ) ) ) | 
						
							| 10 | 7 9 | sylan9eq | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  ( 𝑈  ∈  𝐸  ∧  𝑉  ∈  𝐸 ) )  →  ( 𝑈  +  𝑉 )  =  ( 𝑓  ∈  𝑇  ↦  ( ( 𝑈 ‘ 𝑓 )  ∘  ( 𝑉 ‘ 𝑓 ) ) ) ) |