| Step | Hyp | Ref | Expression | 
						
							| 1 |  | dsmmcl.p | ⊢ 𝑃  =  ( 𝑆 Xs 𝑅 ) | 
						
							| 2 |  | dsmmcl.h | ⊢ 𝐻  =  ( Base ‘ ( 𝑆  ⊕m  𝑅 ) ) | 
						
							| 3 |  | dsmmcl.i | ⊢ ( 𝜑  →  𝐼  ∈  𝑊 ) | 
						
							| 4 |  | dsmmcl.s | ⊢ ( 𝜑  →  𝑆  ∈  𝑉 ) | 
						
							| 5 |  | dsmmcl.r | ⊢ ( 𝜑  →  𝑅 : 𝐼 ⟶ Mnd ) | 
						
							| 6 |  | dsmm0cl.z | ⊢  0   =  ( 0g ‘ 𝑃 ) | 
						
							| 7 | 1 3 4 5 | prdsmndd | ⊢ ( 𝜑  →  𝑃  ∈  Mnd ) | 
						
							| 8 |  | eqid | ⊢ ( Base ‘ 𝑃 )  =  ( Base ‘ 𝑃 ) | 
						
							| 9 | 8 6 | mndidcl | ⊢ ( 𝑃  ∈  Mnd  →   0   ∈  ( Base ‘ 𝑃 ) ) | 
						
							| 10 | 7 9 | syl | ⊢ ( 𝜑  →   0   ∈  ( Base ‘ 𝑃 ) ) | 
						
							| 11 | 1 3 4 5 | prds0g | ⊢ ( 𝜑  →  ( 0g  ∘  𝑅 )  =  ( 0g ‘ 𝑃 ) ) | 
						
							| 12 | 11 6 | eqtr4di | ⊢ ( 𝜑  →  ( 0g  ∘  𝑅 )  =   0  ) | 
						
							| 13 | 12 | adantr | ⊢ ( ( 𝜑  ∧  𝑎  ∈  𝐼 )  →  ( 0g  ∘  𝑅 )  =   0  ) | 
						
							| 14 | 13 | fveq1d | ⊢ ( ( 𝜑  ∧  𝑎  ∈  𝐼 )  →  ( ( 0g  ∘  𝑅 ) ‘ 𝑎 )  =  (  0  ‘ 𝑎 ) ) | 
						
							| 15 | 5 | ffnd | ⊢ ( 𝜑  →  𝑅  Fn  𝐼 ) | 
						
							| 16 |  | fvco2 | ⊢ ( ( 𝑅  Fn  𝐼  ∧  𝑎  ∈  𝐼 )  →  ( ( 0g  ∘  𝑅 ) ‘ 𝑎 )  =  ( 0g ‘ ( 𝑅 ‘ 𝑎 ) ) ) | 
						
							| 17 | 15 16 | sylan | ⊢ ( ( 𝜑  ∧  𝑎  ∈  𝐼 )  →  ( ( 0g  ∘  𝑅 ) ‘ 𝑎 )  =  ( 0g ‘ ( 𝑅 ‘ 𝑎 ) ) ) | 
						
							| 18 | 14 17 | eqtr3d | ⊢ ( ( 𝜑  ∧  𝑎  ∈  𝐼 )  →  (  0  ‘ 𝑎 )  =  ( 0g ‘ ( 𝑅 ‘ 𝑎 ) ) ) | 
						
							| 19 |  | nne | ⊢ ( ¬  (  0  ‘ 𝑎 )  ≠  ( 0g ‘ ( 𝑅 ‘ 𝑎 ) )  ↔  (  0  ‘ 𝑎 )  =  ( 0g ‘ ( 𝑅 ‘ 𝑎 ) ) ) | 
						
							| 20 | 18 19 | sylibr | ⊢ ( ( 𝜑  ∧  𝑎  ∈  𝐼 )  →  ¬  (  0  ‘ 𝑎 )  ≠  ( 0g ‘ ( 𝑅 ‘ 𝑎 ) ) ) | 
						
							| 21 | 20 | ralrimiva | ⊢ ( 𝜑  →  ∀ 𝑎  ∈  𝐼 ¬  (  0  ‘ 𝑎 )  ≠  ( 0g ‘ ( 𝑅 ‘ 𝑎 ) ) ) | 
						
							| 22 |  | rabeq0 | ⊢ ( { 𝑎  ∈  𝐼  ∣  (  0  ‘ 𝑎 )  ≠  ( 0g ‘ ( 𝑅 ‘ 𝑎 ) ) }  =  ∅  ↔  ∀ 𝑎  ∈  𝐼 ¬  (  0  ‘ 𝑎 )  ≠  ( 0g ‘ ( 𝑅 ‘ 𝑎 ) ) ) | 
						
							| 23 | 21 22 | sylibr | ⊢ ( 𝜑  →  { 𝑎  ∈  𝐼  ∣  (  0  ‘ 𝑎 )  ≠  ( 0g ‘ ( 𝑅 ‘ 𝑎 ) ) }  =  ∅ ) | 
						
							| 24 |  | 0fi | ⊢ ∅  ∈  Fin | 
						
							| 25 | 23 24 | eqeltrdi | ⊢ ( 𝜑  →  { 𝑎  ∈  𝐼  ∣  (  0  ‘ 𝑎 )  ≠  ( 0g ‘ ( 𝑅 ‘ 𝑎 ) ) }  ∈  Fin ) | 
						
							| 26 |  | eqid | ⊢ ( 𝑆  ⊕m  𝑅 )  =  ( 𝑆  ⊕m  𝑅 ) | 
						
							| 27 | 1 26 8 2 3 15 | dsmmelbas | ⊢ ( 𝜑  →  (  0   ∈  𝐻  ↔  (  0   ∈  ( Base ‘ 𝑃 )  ∧  { 𝑎  ∈  𝐼  ∣  (  0  ‘ 𝑎 )  ≠  ( 0g ‘ ( 𝑅 ‘ 𝑎 ) ) }  ∈  Fin ) ) ) | 
						
							| 28 | 10 25 27 | mpbir2and | ⊢ ( 𝜑  →   0   ∈  𝐻 ) |