| Step | Hyp | Ref | Expression | 
						
							| 1 |  | rgrusgrprc | ⊢ { 𝑔  ∈  USGraph  ∣  ∀ 𝑣  ∈  ( Vtx ‘ 𝑔 ) ( ( VtxDeg ‘ 𝑔 ) ‘ 𝑣 )  =  0 }  ∉  V | 
						
							| 2 |  | vex | ⊢ 𝑔  ∈  V | 
						
							| 3 |  | 0xnn0 | ⊢ 0  ∈  ℕ0* | 
						
							| 4 |  | eqid | ⊢ ( Vtx ‘ 𝑔 )  =  ( Vtx ‘ 𝑔 ) | 
						
							| 5 |  | eqid | ⊢ ( VtxDeg ‘ 𝑔 )  =  ( VtxDeg ‘ 𝑔 ) | 
						
							| 6 | 4 5 | isrusgr0 | ⊢ ( ( 𝑔  ∈  V  ∧  0  ∈  ℕ0* )  →  ( 𝑔  RegUSGraph  0  ↔  ( 𝑔  ∈  USGraph  ∧  0  ∈  ℕ0*  ∧  ∀ 𝑣  ∈  ( Vtx ‘ 𝑔 ) ( ( VtxDeg ‘ 𝑔 ) ‘ 𝑣 )  =  0 ) ) ) | 
						
							| 7 | 2 3 6 | mp2an | ⊢ ( 𝑔  RegUSGraph  0  ↔  ( 𝑔  ∈  USGraph  ∧  0  ∈  ℕ0*  ∧  ∀ 𝑣  ∈  ( Vtx ‘ 𝑔 ) ( ( VtxDeg ‘ 𝑔 ) ‘ 𝑣 )  =  0 ) ) | 
						
							| 8 |  | 3ancomb | ⊢ ( ( 𝑔  ∈  USGraph  ∧  0  ∈  ℕ0*  ∧  ∀ 𝑣  ∈  ( Vtx ‘ 𝑔 ) ( ( VtxDeg ‘ 𝑔 ) ‘ 𝑣 )  =  0 )  ↔  ( 𝑔  ∈  USGraph  ∧  ∀ 𝑣  ∈  ( Vtx ‘ 𝑔 ) ( ( VtxDeg ‘ 𝑔 ) ‘ 𝑣 )  =  0  ∧  0  ∈  ℕ0* ) ) | 
						
							| 9 |  | df-3an | ⊢ ( ( 𝑔  ∈  USGraph  ∧  ∀ 𝑣  ∈  ( Vtx ‘ 𝑔 ) ( ( VtxDeg ‘ 𝑔 ) ‘ 𝑣 )  =  0  ∧  0  ∈  ℕ0* )  ↔  ( ( 𝑔  ∈  USGraph  ∧  ∀ 𝑣  ∈  ( Vtx ‘ 𝑔 ) ( ( VtxDeg ‘ 𝑔 ) ‘ 𝑣 )  =  0 )  ∧  0  ∈  ℕ0* ) ) | 
						
							| 10 | 3 9 | mpbiran2 | ⊢ ( ( 𝑔  ∈  USGraph  ∧  ∀ 𝑣  ∈  ( Vtx ‘ 𝑔 ) ( ( VtxDeg ‘ 𝑔 ) ‘ 𝑣 )  =  0  ∧  0  ∈  ℕ0* )  ↔  ( 𝑔  ∈  USGraph  ∧  ∀ 𝑣  ∈  ( Vtx ‘ 𝑔 ) ( ( VtxDeg ‘ 𝑔 ) ‘ 𝑣 )  =  0 ) ) | 
						
							| 11 | 7 8 10 | 3bitri | ⊢ ( 𝑔  RegUSGraph  0  ↔  ( 𝑔  ∈  USGraph  ∧  ∀ 𝑣  ∈  ( Vtx ‘ 𝑔 ) ( ( VtxDeg ‘ 𝑔 ) ‘ 𝑣 )  =  0 ) ) | 
						
							| 12 | 11 | abbii | ⊢ { 𝑔  ∣  𝑔  RegUSGraph  0 }  =  { 𝑔  ∣  ( 𝑔  ∈  USGraph  ∧  ∀ 𝑣  ∈  ( Vtx ‘ 𝑔 ) ( ( VtxDeg ‘ 𝑔 ) ‘ 𝑣 )  =  0 ) } | 
						
							| 13 |  | df-rab | ⊢ { 𝑔  ∈  USGraph  ∣  ∀ 𝑣  ∈  ( Vtx ‘ 𝑔 ) ( ( VtxDeg ‘ 𝑔 ) ‘ 𝑣 )  =  0 }  =  { 𝑔  ∣  ( 𝑔  ∈  USGraph  ∧  ∀ 𝑣  ∈  ( Vtx ‘ 𝑔 ) ( ( VtxDeg ‘ 𝑔 ) ‘ 𝑣 )  =  0 ) } | 
						
							| 14 | 12 13 | eqtr4i | ⊢ { 𝑔  ∣  𝑔  RegUSGraph  0 }  =  { 𝑔  ∈  USGraph  ∣  ∀ 𝑣  ∈  ( Vtx ‘ 𝑔 ) ( ( VtxDeg ‘ 𝑔 ) ‘ 𝑣 )  =  0 } | 
						
							| 15 |  | neleq1 | ⊢ ( { 𝑔  ∣  𝑔  RegUSGraph  0 }  =  { 𝑔  ∈  USGraph  ∣  ∀ 𝑣  ∈  ( Vtx ‘ 𝑔 ) ( ( VtxDeg ‘ 𝑔 ) ‘ 𝑣 )  =  0 }  →  ( { 𝑔  ∣  𝑔  RegUSGraph  0 }  ∉  V  ↔  { 𝑔  ∈  USGraph  ∣  ∀ 𝑣  ∈  ( Vtx ‘ 𝑔 ) ( ( VtxDeg ‘ 𝑔 ) ‘ 𝑣 )  =  0 }  ∉  V ) ) | 
						
							| 16 | 14 15 | ax-mp | ⊢ ( { 𝑔  ∣  𝑔  RegUSGraph  0 }  ∉  V  ↔  { 𝑔  ∈  USGraph  ∣  ∀ 𝑣  ∈  ( Vtx ‘ 𝑔 ) ( ( VtxDeg ‘ 𝑔 ) ‘ 𝑣 )  =  0 }  ∉  V ) | 
						
							| 17 | 1 16 | mpbir | ⊢ { 𝑔  ∣  𝑔  RegUSGraph  0 }  ∉  V |