| Step | Hyp | Ref | Expression | 
						
							| 1 |  | ernggrp.h | ⊢ 𝐻  =  ( LHyp ‘ 𝐾 ) | 
						
							| 2 |  | ernggrp.d | ⊢ 𝐷  =  ( ( EDRing ‘ 𝐾 ) ‘ 𝑊 ) | 
						
							| 3 |  | erngdv.b | ⊢ 𝐵  =  ( Base ‘ 𝐾 ) | 
						
							| 4 |  | erngdv.t | ⊢ 𝑇  =  ( ( LTrn ‘ 𝐾 ) ‘ 𝑊 ) | 
						
							| 5 |  | erngdv.e | ⊢ 𝐸  =  ( ( TEndo ‘ 𝐾 ) ‘ 𝑊 ) | 
						
							| 6 |  | erngdv.p | ⊢ 𝑃  =  ( 𝑎  ∈  𝐸 ,  𝑏  ∈  𝐸  ↦  ( 𝑓  ∈  𝑇  ↦  ( ( 𝑎 ‘ 𝑓 )  ∘  ( 𝑏 ‘ 𝑓 ) ) ) ) | 
						
							| 7 |  | erngdv.o | ⊢  0   =  ( 𝑓  ∈  𝑇  ↦  (  I   ↾  𝐵 ) ) | 
						
							| 8 |  | erngdv.i | ⊢ 𝐼  =  ( 𝑎  ∈  𝐸  ↦  ( 𝑓  ∈  𝑇  ↦  ◡ ( 𝑎 ‘ 𝑓 ) ) ) | 
						
							| 9 |  | eqid | ⊢ ( Base ‘ 𝐷 )  =  ( Base ‘ 𝐷 ) | 
						
							| 10 | 1 4 5 2 9 | erngbase | ⊢ ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  →  ( Base ‘ 𝐷 )  =  𝐸 ) | 
						
							| 11 | 10 | eqcomd | ⊢ ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  →  𝐸  =  ( Base ‘ 𝐷 ) ) | 
						
							| 12 |  | eqid | ⊢ ( +g ‘ 𝐷 )  =  ( +g ‘ 𝐷 ) | 
						
							| 13 | 1 4 5 2 12 | erngfplus | ⊢ ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  →  ( +g ‘ 𝐷 )  =  ( 𝑎  ∈  𝐸 ,  𝑏  ∈  𝐸  ↦  ( 𝑓  ∈  𝑇  ↦  ( ( 𝑎 ‘ 𝑓 )  ∘  ( 𝑏 ‘ 𝑓 ) ) ) ) ) | 
						
							| 14 | 6 13 | eqtr4id | ⊢ ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  →  𝑃  =  ( +g ‘ 𝐷 ) ) | 
						
							| 15 | 1 2 3 4 5 6 7 8 | erngdvlem1 | ⊢ ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  →  𝐷  ∈  Grp ) | 
						
							| 16 | 1 4 5 6 | tendoplcom | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  𝑠  ∈  𝐸  ∧  𝑡  ∈  𝐸 )  →  ( 𝑠 𝑃 𝑡 )  =  ( 𝑡 𝑃 𝑠 ) ) | 
						
							| 17 | 11 14 15 16 | isabld | ⊢ ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  →  𝐷  ∈  Abel ) |