| Step | Hyp | Ref | Expression | 
						
							| 1 |  | eqid |  |-  ( Vtx ` G ) = ( Vtx ` G ) | 
						
							| 2 |  | eqid |  |-  ( iEdg ` G ) = ( iEdg ` G ) | 
						
							| 3 | 1 2 | isuspgr |  |-  ( G e. USPGraph -> ( G e. USPGraph <-> ( iEdg ` G ) : dom ( iEdg ` G ) -1-1-> { x e. ( ~P ( Vtx ` G ) \ { (/) } ) | ( # ` x ) <_ 2 } ) ) | 
						
							| 4 |  | ssrab2 |  |-  { x e. ( ~P ( Vtx ` G ) \ { (/) } ) | ( # ` x ) <_ 2 } C_ ( ~P ( Vtx ` G ) \ { (/) } ) | 
						
							| 5 |  | f1ss |  |-  ( ( ( iEdg ` G ) : dom ( iEdg ` G ) -1-1-> { x e. ( ~P ( Vtx ` G ) \ { (/) } ) | ( # ` x ) <_ 2 } /\ { x e. ( ~P ( Vtx ` G ) \ { (/) } ) | ( # ` x ) <_ 2 } C_ ( ~P ( Vtx ` G ) \ { (/) } ) ) -> ( iEdg ` G ) : dom ( iEdg ` G ) -1-1-> ( ~P ( Vtx ` G ) \ { (/) } ) ) | 
						
							| 6 | 4 5 | mpan2 |  |-  ( ( iEdg ` G ) : dom ( iEdg ` G ) -1-1-> { x e. ( ~P ( Vtx ` G ) \ { (/) } ) | ( # ` x ) <_ 2 } -> ( iEdg ` G ) : dom ( iEdg ` G ) -1-1-> ( ~P ( Vtx ` G ) \ { (/) } ) ) | 
						
							| 7 | 3 6 | biimtrdi |  |-  ( G e. USPGraph -> ( G e. USPGraph -> ( iEdg ` G ) : dom ( iEdg ` G ) -1-1-> ( ~P ( Vtx ` G ) \ { (/) } ) ) ) | 
						
							| 8 | 1 2 | isushgr |  |-  ( G e. USPGraph -> ( G e. USHGraph <-> ( iEdg ` G ) : dom ( iEdg ` G ) -1-1-> ( ~P ( Vtx ` G ) \ { (/) } ) ) ) | 
						
							| 9 | 7 8 | sylibrd |  |-  ( G e. USPGraph -> ( G e. USPGraph -> G e. USHGraph ) ) | 
						
							| 10 | 9 | pm2.43i |  |-  ( G e. USPGraph -> G e. USHGraph ) |