| Step | Hyp | Ref | Expression | 
						
							| 1 |  | 0ex | ⊢ ∅  ∈  V | 
						
							| 2 |  | base0 | ⊢ ∅  =  ( Base ‘ ∅ ) | 
						
							| 3 |  | 00lss | ⊢ ∅  =  ( LSubSp ‘ ∅ ) | 
						
							| 4 |  | eqid | ⊢ ( LSpan ‘ ∅ )  =  ( LSpan ‘ ∅ ) | 
						
							| 5 | 2 3 4 | lspfval | ⊢ ( ∅  ∈  V  →  ( LSpan ‘ ∅ )  =  ( 𝑎  ∈  𝒫  ∅  ↦  ∩  { 𝑏  ∈  ∅  ∣  𝑎  ⊆  𝑏 } ) ) | 
						
							| 6 | 1 5 | ax-mp | ⊢ ( LSpan ‘ ∅ )  =  ( 𝑎  ∈  𝒫  ∅  ↦  ∩  { 𝑏  ∈  ∅  ∣  𝑎  ⊆  𝑏 } ) | 
						
							| 7 |  | eqid | ⊢ ( 𝑎  ∈  𝒫  ∅  ↦  ∩  { 𝑏  ∈  ∅  ∣  𝑎  ⊆  𝑏 } )  =  ( 𝑎  ∈  𝒫  ∅  ↦  ∩  { 𝑏  ∈  ∅  ∣  𝑎  ⊆  𝑏 } ) | 
						
							| 8 | 7 | dmmpt | ⊢ dom  ( 𝑎  ∈  𝒫  ∅  ↦  ∩  { 𝑏  ∈  ∅  ∣  𝑎  ⊆  𝑏 } )  =  { 𝑎  ∈  𝒫  ∅  ∣  ∩  { 𝑏  ∈  ∅  ∣  𝑎  ⊆  𝑏 }  ∈  V } | 
						
							| 9 |  | rab0 | ⊢ { 𝑏  ∈  ∅  ∣  𝑎  ⊆  𝑏 }  =  ∅ | 
						
							| 10 | 9 | inteqi | ⊢ ∩  { 𝑏  ∈  ∅  ∣  𝑎  ⊆  𝑏 }  =  ∩  ∅ | 
						
							| 11 |  | int0 | ⊢ ∩  ∅  =  V | 
						
							| 12 | 10 11 | eqtri | ⊢ ∩  { 𝑏  ∈  ∅  ∣  𝑎  ⊆  𝑏 }  =  V | 
						
							| 13 |  | vprc | ⊢ ¬  V  ∈  V | 
						
							| 14 | 12 13 | eqneltri | ⊢ ¬  ∩  { 𝑏  ∈  ∅  ∣  𝑎  ⊆  𝑏 }  ∈  V | 
						
							| 15 | 14 | rgenw | ⊢ ∀ 𝑎  ∈  𝒫  ∅ ¬  ∩  { 𝑏  ∈  ∅  ∣  𝑎  ⊆  𝑏 }  ∈  V | 
						
							| 16 |  | rabeq0 | ⊢ ( { 𝑎  ∈  𝒫  ∅  ∣  ∩  { 𝑏  ∈  ∅  ∣  𝑎  ⊆  𝑏 }  ∈  V }  =  ∅  ↔  ∀ 𝑎  ∈  𝒫  ∅ ¬  ∩  { 𝑏  ∈  ∅  ∣  𝑎  ⊆  𝑏 }  ∈  V ) | 
						
							| 17 | 15 16 | mpbir | ⊢ { 𝑎  ∈  𝒫  ∅  ∣  ∩  { 𝑏  ∈  ∅  ∣  𝑎  ⊆  𝑏 }  ∈  V }  =  ∅ | 
						
							| 18 | 8 17 | eqtri | ⊢ dom  ( 𝑎  ∈  𝒫  ∅  ↦  ∩  { 𝑏  ∈  ∅  ∣  𝑎  ⊆  𝑏 } )  =  ∅ | 
						
							| 19 |  | mptrel | ⊢ Rel  ( 𝑎  ∈  𝒫  ∅  ↦  ∩  { 𝑏  ∈  ∅  ∣  𝑎  ⊆  𝑏 } ) | 
						
							| 20 |  | reldm0 | ⊢ ( Rel  ( 𝑎  ∈  𝒫  ∅  ↦  ∩  { 𝑏  ∈  ∅  ∣  𝑎  ⊆  𝑏 } )  →  ( ( 𝑎  ∈  𝒫  ∅  ↦  ∩  { 𝑏  ∈  ∅  ∣  𝑎  ⊆  𝑏 } )  =  ∅  ↔  dom  ( 𝑎  ∈  𝒫  ∅  ↦  ∩  { 𝑏  ∈  ∅  ∣  𝑎  ⊆  𝑏 } )  =  ∅ ) ) | 
						
							| 21 | 19 20 | ax-mp | ⊢ ( ( 𝑎  ∈  𝒫  ∅  ↦  ∩  { 𝑏  ∈  ∅  ∣  𝑎  ⊆  𝑏 } )  =  ∅  ↔  dom  ( 𝑎  ∈  𝒫  ∅  ↦  ∩  { 𝑏  ∈  ∅  ∣  𝑎  ⊆  𝑏 } )  =  ∅ ) | 
						
							| 22 | 18 21 | mpbir | ⊢ ( 𝑎  ∈  𝒫  ∅  ↦  ∩  { 𝑏  ∈  ∅  ∣  𝑎  ⊆  𝑏 } )  =  ∅ | 
						
							| 23 | 6 22 | eqtr2i | ⊢ ∅  =  ( LSpan ‘ ∅ ) |