| Step | Hyp | Ref | Expression | 
						
							| 1 |  | ausgr.1 | ⊢ 𝐺  =  { 〈 𝑣 ,  𝑒 〉  ∣  𝑒  ⊆  { 𝑥  ∈  𝒫  𝑣  ∣  ( ♯ ‘ 𝑥 )  =  2 } } | 
						
							| 2 |  | ausgrusgri.1 | ⊢ 𝑂  =  { 𝑓  ∣  𝑓 : dom  𝑓 –1-1→ ran  𝑓 } | 
						
							| 3 |  | fvex | ⊢ ( Vtx ‘ 𝐻 )  ∈  V | 
						
							| 4 |  | fvex | ⊢ ( Edg ‘ 𝐻 )  ∈  V | 
						
							| 5 | 1 | isausgr | ⊢ ( ( ( Vtx ‘ 𝐻 )  ∈  V  ∧  ( Edg ‘ 𝐻 )  ∈  V )  →  ( ( Vtx ‘ 𝐻 ) 𝐺 ( Edg ‘ 𝐻 )  ↔  ( Edg ‘ 𝐻 )  ⊆  { 𝑥  ∈  𝒫  ( Vtx ‘ 𝐻 )  ∣  ( ♯ ‘ 𝑥 )  =  2 } ) ) | 
						
							| 6 | 3 4 5 | mp2an | ⊢ ( ( Vtx ‘ 𝐻 ) 𝐺 ( Edg ‘ 𝐻 )  ↔  ( Edg ‘ 𝐻 )  ⊆  { 𝑥  ∈  𝒫  ( Vtx ‘ 𝐻 )  ∣  ( ♯ ‘ 𝑥 )  =  2 } ) | 
						
							| 7 |  | edgval | ⊢ ( Edg ‘ 𝐻 )  =  ran  ( iEdg ‘ 𝐻 ) | 
						
							| 8 | 7 | a1i | ⊢ ( 𝐻  ∈  𝑊  →  ( Edg ‘ 𝐻 )  =  ran  ( iEdg ‘ 𝐻 ) ) | 
						
							| 9 | 8 | sseq1d | ⊢ ( 𝐻  ∈  𝑊  →  ( ( Edg ‘ 𝐻 )  ⊆  { 𝑥  ∈  𝒫  ( Vtx ‘ 𝐻 )  ∣  ( ♯ ‘ 𝑥 )  =  2 }  ↔  ran  ( iEdg ‘ 𝐻 )  ⊆  { 𝑥  ∈  𝒫  ( Vtx ‘ 𝐻 )  ∣  ( ♯ ‘ 𝑥 )  =  2 } ) ) | 
						
							| 10 | 2 | eleq2i | ⊢ ( ( iEdg ‘ 𝐻 )  ∈  𝑂  ↔  ( iEdg ‘ 𝐻 )  ∈  { 𝑓  ∣  𝑓 : dom  𝑓 –1-1→ ran  𝑓 } ) | 
						
							| 11 |  | fvex | ⊢ ( iEdg ‘ 𝐻 )  ∈  V | 
						
							| 12 |  | id | ⊢ ( 𝑓  =  ( iEdg ‘ 𝐻 )  →  𝑓  =  ( iEdg ‘ 𝐻 ) ) | 
						
							| 13 |  | dmeq | ⊢ ( 𝑓  =  ( iEdg ‘ 𝐻 )  →  dom  𝑓  =  dom  ( iEdg ‘ 𝐻 ) ) | 
						
							| 14 |  | rneq | ⊢ ( 𝑓  =  ( iEdg ‘ 𝐻 )  →  ran  𝑓  =  ran  ( iEdg ‘ 𝐻 ) ) | 
						
							| 15 | 12 13 14 | f1eq123d | ⊢ ( 𝑓  =  ( iEdg ‘ 𝐻 )  →  ( 𝑓 : dom  𝑓 –1-1→ ran  𝑓  ↔  ( iEdg ‘ 𝐻 ) : dom  ( iEdg ‘ 𝐻 ) –1-1→ ran  ( iEdg ‘ 𝐻 ) ) ) | 
						
							| 16 | 11 15 | elab | ⊢ ( ( iEdg ‘ 𝐻 )  ∈  { 𝑓  ∣  𝑓 : dom  𝑓 –1-1→ ran  𝑓 }  ↔  ( iEdg ‘ 𝐻 ) : dom  ( iEdg ‘ 𝐻 ) –1-1→ ran  ( iEdg ‘ 𝐻 ) ) | 
						
							| 17 | 10 16 | sylbb | ⊢ ( ( iEdg ‘ 𝐻 )  ∈  𝑂  →  ( iEdg ‘ 𝐻 ) : dom  ( iEdg ‘ 𝐻 ) –1-1→ ran  ( iEdg ‘ 𝐻 ) ) | 
						
							| 18 | 17 | 3ad2ant3 | ⊢ ( ( 𝐻  ∈  𝑊  ∧  ran  ( iEdg ‘ 𝐻 )  ⊆  { 𝑥  ∈  𝒫  ( Vtx ‘ 𝐻 )  ∣  ( ♯ ‘ 𝑥 )  =  2 }  ∧  ( iEdg ‘ 𝐻 )  ∈  𝑂 )  →  ( iEdg ‘ 𝐻 ) : dom  ( iEdg ‘ 𝐻 ) –1-1→ ran  ( iEdg ‘ 𝐻 ) ) | 
						
							| 19 |  | simp2 | ⊢ ( ( 𝐻  ∈  𝑊  ∧  ran  ( iEdg ‘ 𝐻 )  ⊆  { 𝑥  ∈  𝒫  ( Vtx ‘ 𝐻 )  ∣  ( ♯ ‘ 𝑥 )  =  2 }  ∧  ( iEdg ‘ 𝐻 )  ∈  𝑂 )  →  ran  ( iEdg ‘ 𝐻 )  ⊆  { 𝑥  ∈  𝒫  ( Vtx ‘ 𝐻 )  ∣  ( ♯ ‘ 𝑥 )  =  2 } ) | 
						
							| 20 |  | f1ssr | ⊢ ( ( ( iEdg ‘ 𝐻 ) : dom  ( iEdg ‘ 𝐻 ) –1-1→ ran  ( iEdg ‘ 𝐻 )  ∧  ran  ( iEdg ‘ 𝐻 )  ⊆  { 𝑥  ∈  𝒫  ( Vtx ‘ 𝐻 )  ∣  ( ♯ ‘ 𝑥 )  =  2 } )  →  ( iEdg ‘ 𝐻 ) : dom  ( iEdg ‘ 𝐻 ) –1-1→ { 𝑥  ∈  𝒫  ( Vtx ‘ 𝐻 )  ∣  ( ♯ ‘ 𝑥 )  =  2 } ) | 
						
							| 21 | 18 19 20 | syl2anc | ⊢ ( ( 𝐻  ∈  𝑊  ∧  ran  ( iEdg ‘ 𝐻 )  ⊆  { 𝑥  ∈  𝒫  ( Vtx ‘ 𝐻 )  ∣  ( ♯ ‘ 𝑥 )  =  2 }  ∧  ( iEdg ‘ 𝐻 )  ∈  𝑂 )  →  ( iEdg ‘ 𝐻 ) : dom  ( iEdg ‘ 𝐻 ) –1-1→ { 𝑥  ∈  𝒫  ( Vtx ‘ 𝐻 )  ∣  ( ♯ ‘ 𝑥 )  =  2 } ) | 
						
							| 22 | 21 | 3exp | ⊢ ( 𝐻  ∈  𝑊  →  ( ran  ( iEdg ‘ 𝐻 )  ⊆  { 𝑥  ∈  𝒫  ( Vtx ‘ 𝐻 )  ∣  ( ♯ ‘ 𝑥 )  =  2 }  →  ( ( iEdg ‘ 𝐻 )  ∈  𝑂  →  ( iEdg ‘ 𝐻 ) : dom  ( iEdg ‘ 𝐻 ) –1-1→ { 𝑥  ∈  𝒫  ( Vtx ‘ 𝐻 )  ∣  ( ♯ ‘ 𝑥 )  =  2 } ) ) ) | 
						
							| 23 | 9 22 | sylbid | ⊢ ( 𝐻  ∈  𝑊  →  ( ( Edg ‘ 𝐻 )  ⊆  { 𝑥  ∈  𝒫  ( Vtx ‘ 𝐻 )  ∣  ( ♯ ‘ 𝑥 )  =  2 }  →  ( ( iEdg ‘ 𝐻 )  ∈  𝑂  →  ( iEdg ‘ 𝐻 ) : dom  ( iEdg ‘ 𝐻 ) –1-1→ { 𝑥  ∈  𝒫  ( Vtx ‘ 𝐻 )  ∣  ( ♯ ‘ 𝑥 )  =  2 } ) ) ) | 
						
							| 24 | 6 23 | biimtrid | ⊢ ( 𝐻  ∈  𝑊  →  ( ( Vtx ‘ 𝐻 ) 𝐺 ( Edg ‘ 𝐻 )  →  ( ( iEdg ‘ 𝐻 )  ∈  𝑂  →  ( iEdg ‘ 𝐻 ) : dom  ( iEdg ‘ 𝐻 ) –1-1→ { 𝑥  ∈  𝒫  ( Vtx ‘ 𝐻 )  ∣  ( ♯ ‘ 𝑥 )  =  2 } ) ) ) | 
						
							| 25 | 24 | 3imp | ⊢ ( ( 𝐻  ∈  𝑊  ∧  ( Vtx ‘ 𝐻 ) 𝐺 ( Edg ‘ 𝐻 )  ∧  ( iEdg ‘ 𝐻 )  ∈  𝑂 )  →  ( iEdg ‘ 𝐻 ) : dom  ( iEdg ‘ 𝐻 ) –1-1→ { 𝑥  ∈  𝒫  ( Vtx ‘ 𝐻 )  ∣  ( ♯ ‘ 𝑥 )  =  2 } ) | 
						
							| 26 |  | eqid | ⊢ ( Vtx ‘ 𝐻 )  =  ( Vtx ‘ 𝐻 ) | 
						
							| 27 |  | eqid | ⊢ ( iEdg ‘ 𝐻 )  =  ( iEdg ‘ 𝐻 ) | 
						
							| 28 | 26 27 | isusgrs | ⊢ ( 𝐻  ∈  𝑊  →  ( 𝐻  ∈  USGraph  ↔  ( iEdg ‘ 𝐻 ) : dom  ( iEdg ‘ 𝐻 ) –1-1→ { 𝑥  ∈  𝒫  ( Vtx ‘ 𝐻 )  ∣  ( ♯ ‘ 𝑥 )  =  2 } ) ) | 
						
							| 29 | 28 | 3ad2ant1 | ⊢ ( ( 𝐻  ∈  𝑊  ∧  ( Vtx ‘ 𝐻 ) 𝐺 ( Edg ‘ 𝐻 )  ∧  ( iEdg ‘ 𝐻 )  ∈  𝑂 )  →  ( 𝐻  ∈  USGraph  ↔  ( iEdg ‘ 𝐻 ) : dom  ( iEdg ‘ 𝐻 ) –1-1→ { 𝑥  ∈  𝒫  ( Vtx ‘ 𝐻 )  ∣  ( ♯ ‘ 𝑥 )  =  2 } ) ) | 
						
							| 30 | 25 29 | mpbird | ⊢ ( ( 𝐻  ∈  𝑊  ∧  ( Vtx ‘ 𝐻 ) 𝐺 ( Edg ‘ 𝐻 )  ∧  ( iEdg ‘ 𝐻 )  ∈  𝑂 )  →  𝐻  ∈  USGraph ) |