| Step | Hyp | Ref | Expression | 
						
							| 1 |  | eqid | ⊢ ( Vtx ‘ 𝐺 )  =  ( Vtx ‘ 𝐺 ) | 
						
							| 2 |  | eqid | ⊢ ( iEdg ‘ 𝐺 )  =  ( iEdg ‘ 𝐺 ) | 
						
							| 3 | 1 2 | upgrf | ⊢ ( 𝐺  ∈  UPGraph  →  ( iEdg ‘ 𝐺 ) : dom  ( iEdg ‘ 𝐺 ) ⟶ { 𝑥  ∈  ( 𝒫  ( Vtx ‘ 𝐺 )  ∖  { ∅ } )  ∣  ( ♯ ‘ 𝑥 )  ≤  2 } ) | 
						
							| 4 |  | ssrab2 | ⊢ { 𝑥  ∈  ( 𝒫  ( Vtx ‘ 𝐺 )  ∖  { ∅ } )  ∣  ( ♯ ‘ 𝑥 )  ≤  2 }  ⊆  ( 𝒫  ( Vtx ‘ 𝐺 )  ∖  { ∅ } ) | 
						
							| 5 |  | fss | ⊢ ( ( ( iEdg ‘ 𝐺 ) : dom  ( iEdg ‘ 𝐺 ) ⟶ { 𝑥  ∈  ( 𝒫  ( Vtx ‘ 𝐺 )  ∖  { ∅ } )  ∣  ( ♯ ‘ 𝑥 )  ≤  2 }  ∧  { 𝑥  ∈  ( 𝒫  ( Vtx ‘ 𝐺 )  ∖  { ∅ } )  ∣  ( ♯ ‘ 𝑥 )  ≤  2 }  ⊆  ( 𝒫  ( Vtx ‘ 𝐺 )  ∖  { ∅ } ) )  →  ( iEdg ‘ 𝐺 ) : dom  ( iEdg ‘ 𝐺 ) ⟶ ( 𝒫  ( Vtx ‘ 𝐺 )  ∖  { ∅ } ) ) | 
						
							| 6 | 3 4 5 | sylancl | ⊢ ( 𝐺  ∈  UPGraph  →  ( iEdg ‘ 𝐺 ) : dom  ( iEdg ‘ 𝐺 ) ⟶ ( 𝒫  ( Vtx ‘ 𝐺 )  ∖  { ∅ } ) ) | 
						
							| 7 | 1 2 | isuhgr | ⊢ ( 𝐺  ∈  UPGraph  →  ( 𝐺  ∈  UHGraph  ↔  ( iEdg ‘ 𝐺 ) : dom  ( iEdg ‘ 𝐺 ) ⟶ ( 𝒫  ( Vtx ‘ 𝐺 )  ∖  { ∅ } ) ) ) | 
						
							| 8 | 6 7 | mpbird | ⊢ ( 𝐺  ∈  UPGraph  →  𝐺  ∈  UHGraph ) |