| Step | Hyp | Ref | Expression | 
						
							| 1 |  | eqid | ⊢ ( Vtx ‘ 𝐺 )  =  ( Vtx ‘ 𝐺 ) | 
						
							| 2 |  | eqid | ⊢ ( iEdg ‘ 𝐺 )  =  ( iEdg ‘ 𝐺 ) | 
						
							| 3 | 1 2 | isuspgr | ⊢ ( 𝐺  ∈  USPGraph  →  ( 𝐺  ∈  USPGraph  ↔  ( iEdg ‘ 𝐺 ) : dom  ( iEdg ‘ 𝐺 ) –1-1→ { 𝑥  ∈  ( 𝒫  ( Vtx ‘ 𝐺 )  ∖  { ∅ } )  ∣  ( ♯ ‘ 𝑥 )  ≤  2 } ) ) | 
						
							| 4 |  | f1f | ⊢ ( ( iEdg ‘ 𝐺 ) : dom  ( iEdg ‘ 𝐺 ) –1-1→ { 𝑥  ∈  ( 𝒫  ( Vtx ‘ 𝐺 )  ∖  { ∅ } )  ∣  ( ♯ ‘ 𝑥 )  ≤  2 }  →  ( iEdg ‘ 𝐺 ) : dom  ( iEdg ‘ 𝐺 ) ⟶ { 𝑥  ∈  ( 𝒫  ( Vtx ‘ 𝐺 )  ∖  { ∅ } )  ∣  ( ♯ ‘ 𝑥 )  ≤  2 } ) | 
						
							| 5 | 3 4 | biimtrdi | ⊢ ( 𝐺  ∈  USPGraph  →  ( 𝐺  ∈  USPGraph  →  ( iEdg ‘ 𝐺 ) : dom  ( iEdg ‘ 𝐺 ) ⟶ { 𝑥  ∈  ( 𝒫  ( Vtx ‘ 𝐺 )  ∖  { ∅ } )  ∣  ( ♯ ‘ 𝑥 )  ≤  2 } ) ) | 
						
							| 6 | 1 2 | isupgr | ⊢ ( 𝐺  ∈  USPGraph  →  ( 𝐺  ∈  UPGraph  ↔  ( iEdg ‘ 𝐺 ) : dom  ( iEdg ‘ 𝐺 ) ⟶ { 𝑥  ∈  ( 𝒫  ( Vtx ‘ 𝐺 )  ∖  { ∅ } )  ∣  ( ♯ ‘ 𝑥 )  ≤  2 } ) ) | 
						
							| 7 | 5 6 | sylibrd | ⊢ ( 𝐺  ∈  USPGraph  →  ( 𝐺  ∈  USPGraph  →  𝐺  ∈  UPGraph ) ) | 
						
							| 8 | 7 | pm2.43i | ⊢ ( 𝐺  ∈  USPGraph  →  𝐺  ∈  UPGraph ) |