| Step | Hyp | Ref | Expression | 
						
							| 1 |  | elopab |  |-  ( p e. { <. v , e >. | e : (/) --> (/) } <-> E. v E. e ( p = <. v , e >. /\ e : (/) --> (/) ) ) | 
						
							| 2 |  | f0bi |  |-  ( e : (/) --> (/) <-> e = (/) ) | 
						
							| 3 |  | opeq2 |  |-  ( e = (/) -> <. v , e >. = <. v , (/) >. ) | 
						
							| 4 |  | usgr0eop |  |-  ( v e. _V -> <. v , (/) >. e. USGraph ) | 
						
							| 5 | 4 | elv |  |-  <. v , (/) >. e. USGraph | 
						
							| 6 | 3 5 | eqeltrdi |  |-  ( e = (/) -> <. v , e >. e. USGraph ) | 
						
							| 7 |  | vex |  |-  v e. _V | 
						
							| 8 |  | vex |  |-  e e. _V | 
						
							| 9 | 7 8 | opiedgfvi |  |-  ( iEdg ` <. v , e >. ) = e | 
						
							| 10 |  | id |  |-  ( e = (/) -> e = (/) ) | 
						
							| 11 | 9 10 | eqtrid |  |-  ( e = (/) -> ( iEdg ` <. v , e >. ) = (/) ) | 
						
							| 12 | 6 11 | jca |  |-  ( e = (/) -> ( <. v , e >. e. USGraph /\ ( iEdg ` <. v , e >. ) = (/) ) ) | 
						
							| 13 | 2 12 | sylbi |  |-  ( e : (/) --> (/) -> ( <. v , e >. e. USGraph /\ ( iEdg ` <. v , e >. ) = (/) ) ) | 
						
							| 14 | 13 | adantl |  |-  ( ( p = <. v , e >. /\ e : (/) --> (/) ) -> ( <. v , e >. e. USGraph /\ ( iEdg ` <. v , e >. ) = (/) ) ) | 
						
							| 15 |  | eleq1 |  |-  ( p = <. v , e >. -> ( p e. USGraph <-> <. v , e >. e. USGraph ) ) | 
						
							| 16 |  | fveqeq2 |  |-  ( p = <. v , e >. -> ( ( iEdg ` p ) = (/) <-> ( iEdg ` <. v , e >. ) = (/) ) ) | 
						
							| 17 | 15 16 | anbi12d |  |-  ( p = <. v , e >. -> ( ( p e. USGraph /\ ( iEdg ` p ) = (/) ) <-> ( <. v , e >. e. USGraph /\ ( iEdg ` <. v , e >. ) = (/) ) ) ) | 
						
							| 18 | 17 | adantr |  |-  ( ( p = <. v , e >. /\ e : (/) --> (/) ) -> ( ( p e. USGraph /\ ( iEdg ` p ) = (/) ) <-> ( <. v , e >. e. USGraph /\ ( iEdg ` <. v , e >. ) = (/) ) ) ) | 
						
							| 19 | 14 18 | mpbird |  |-  ( ( p = <. v , e >. /\ e : (/) --> (/) ) -> ( p e. USGraph /\ ( iEdg ` p ) = (/) ) ) | 
						
							| 20 |  | fveqeq2 |  |-  ( g = p -> ( ( iEdg ` g ) = (/) <-> ( iEdg ` p ) = (/) ) ) | 
						
							| 21 | 20 | elrab |  |-  ( p e. { g e. USGraph | ( iEdg ` g ) = (/) } <-> ( p e. USGraph /\ ( iEdg ` p ) = (/) ) ) | 
						
							| 22 | 19 21 | sylibr |  |-  ( ( p = <. v , e >. /\ e : (/) --> (/) ) -> p e. { g e. USGraph | ( iEdg ` g ) = (/) } ) | 
						
							| 23 | 22 | exlimivv |  |-  ( E. v E. e ( p = <. v , e >. /\ e : (/) --> (/) ) -> p e. { g e. USGraph | ( iEdg ` g ) = (/) } ) | 
						
							| 24 | 1 23 | sylbi |  |-  ( p e. { <. v , e >. | e : (/) --> (/) } -> p e. { g e. USGraph | ( iEdg ` g ) = (/) } ) | 
						
							| 25 | 24 | ssriv |  |-  { <. v , e >. | e : (/) --> (/) } C_ { g e. USGraph | ( iEdg ` g ) = (/) } | 
						
							| 26 |  | eqid |  |-  { <. v , e >. | e : (/) --> (/) } = { <. v , e >. | e : (/) --> (/) } | 
						
							| 27 | 26 | griedg0prc |  |-  { <. v , e >. | e : (/) --> (/) } e/ _V | 
						
							| 28 |  | prcssprc |  |-  ( ( { <. v , e >. | e : (/) --> (/) } C_ { g e. USGraph | ( iEdg ` g ) = (/) } /\ { <. v , e >. | e : (/) --> (/) } e/ _V ) -> { g e. USGraph | ( iEdg ` g ) = (/) } e/ _V ) | 
						
							| 29 | 25 27 28 | mp2an |  |-  { g e. USGraph | ( iEdg ` g ) = (/) } e/ _V | 
						
							| 30 |  | df-3an |  |-  ( ( g e. USGraph /\ 0 e. NN0* /\ A. v e. ( Vtx ` g ) ( ( VtxDeg ` g ) ` v ) = 0 ) <-> ( ( g e. USGraph /\ 0 e. NN0* ) /\ A. v e. ( Vtx ` g ) ( ( VtxDeg ` g ) ` v ) = 0 ) ) | 
						
							| 31 | 30 | bicomi |  |-  ( ( ( g e. USGraph /\ 0 e. NN0* ) /\ A. v e. ( Vtx ` g ) ( ( VtxDeg ` g ) ` v ) = 0 ) <-> ( g e. USGraph /\ 0 e. NN0* /\ A. v e. ( Vtx ` g ) ( ( VtxDeg ` g ) ` v ) = 0 ) ) | 
						
							| 32 | 31 | a1i |  |-  ( g e. USGraph -> ( ( ( g e. USGraph /\ 0 e. NN0* ) /\ A. v e. ( Vtx ` g ) ( ( VtxDeg ` g ) ` v ) = 0 ) <-> ( g e. USGraph /\ 0 e. NN0* /\ A. v e. ( Vtx ` g ) ( ( VtxDeg ` g ) ` v ) = 0 ) ) ) | 
						
							| 33 |  | 0xnn0 |  |-  0 e. NN0* | 
						
							| 34 |  | ibar |  |-  ( ( g e. USGraph /\ 0 e. NN0* ) -> ( A. v e. ( Vtx ` g ) ( ( VtxDeg ` g ) ` v ) = 0 <-> ( ( g e. USGraph /\ 0 e. NN0* ) /\ A. v e. ( Vtx ` g ) ( ( VtxDeg ` g ) ` v ) = 0 ) ) ) | 
						
							| 35 | 33 34 | mpan2 |  |-  ( g e. USGraph -> ( A. v e. ( Vtx ` g ) ( ( VtxDeg ` g ) ` v ) = 0 <-> ( ( g e. USGraph /\ 0 e. NN0* ) /\ A. v e. ( Vtx ` g ) ( ( VtxDeg ` g ) ` v ) = 0 ) ) ) | 
						
							| 36 |  | eqid |  |-  ( Vtx ` g ) = ( Vtx ` g ) | 
						
							| 37 |  | eqid |  |-  ( VtxDeg ` g ) = ( VtxDeg ` g ) | 
						
							| 38 | 36 37 | isrusgr0 |  |-  ( ( g e. USGraph /\ 0 e. NN0* ) -> ( g RegUSGraph 0 <-> ( g e. USGraph /\ 0 e. NN0* /\ A. v e. ( Vtx ` g ) ( ( VtxDeg ` g ) ` v ) = 0 ) ) ) | 
						
							| 39 | 33 38 | mpan2 |  |-  ( g e. USGraph -> ( g RegUSGraph 0 <-> ( g e. USGraph /\ 0 e. NN0* /\ A. v e. ( Vtx ` g ) ( ( VtxDeg ` g ) ` v ) = 0 ) ) ) | 
						
							| 40 | 32 35 39 | 3bitr4d |  |-  ( g e. USGraph -> ( A. v e. ( Vtx ` g ) ( ( VtxDeg ` g ) ` v ) = 0 <-> g RegUSGraph 0 ) ) | 
						
							| 41 | 40 | rabbiia |  |-  { g e. USGraph | A. v e. ( Vtx ` g ) ( ( VtxDeg ` g ) ` v ) = 0 } = { g e. USGraph | g RegUSGraph 0 } | 
						
							| 42 |  | usgr0edg0rusgr |  |-  ( g e. USGraph -> ( g RegUSGraph 0 <-> ( Edg ` g ) = (/) ) ) | 
						
							| 43 |  | usgruhgr |  |-  ( g e. USGraph -> g e. UHGraph ) | 
						
							| 44 |  | uhgriedg0edg0 |  |-  ( g e. UHGraph -> ( ( Edg ` g ) = (/) <-> ( iEdg ` g ) = (/) ) ) | 
						
							| 45 | 43 44 | syl |  |-  ( g e. USGraph -> ( ( Edg ` g ) = (/) <-> ( iEdg ` g ) = (/) ) ) | 
						
							| 46 | 42 45 | bitrd |  |-  ( g e. USGraph -> ( g RegUSGraph 0 <-> ( iEdg ` g ) = (/) ) ) | 
						
							| 47 | 46 | rabbiia |  |-  { g e. USGraph | g RegUSGraph 0 } = { g e. USGraph | ( iEdg ` g ) = (/) } | 
						
							| 48 | 41 47 | eqtri |  |-  { g e. USGraph | A. v e. ( Vtx ` g ) ( ( VtxDeg ` g ) ` v ) = 0 } = { g e. USGraph | ( iEdg ` g ) = (/) } | 
						
							| 49 |  | neleq1 |  |-  ( { g e. USGraph | A. v e. ( Vtx ` g ) ( ( VtxDeg ` g ) ` v ) = 0 } = { g e. USGraph | ( iEdg ` g ) = (/) } -> ( { g e. USGraph | A. v e. ( Vtx ` g ) ( ( VtxDeg ` g ) ` v ) = 0 } e/ _V <-> { g e. USGraph | ( iEdg ` g ) = (/) } e/ _V ) ) | 
						
							| 50 | 48 49 | ax-mp |  |-  ( { g e. USGraph | A. v e. ( Vtx ` g ) ( ( VtxDeg ` g ) ` v ) = 0 } e/ _V <-> { g e. USGraph | ( iEdg ` g ) = (/) } e/ _V ) | 
						
							| 51 | 29 50 | mpbir |  |-  { g e. USGraph | A. v e. ( Vtx ` g ) ( ( VtxDeg ` g ) ` v ) = 0 } e/ _V |