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Metamath Proof Explorer

Theorem usgrexmpl

Description: G is a simple graph of five vertices 0 , 1 , 2 , 3 , 4 , with edges { 0 , 1 } , { 1 , 2 } , { 2 , 0 } , { 0 , 3 } . (Contributed by Alexander van der Vekens, 15-Aug-2017) (Revised by AV, 21-Oct-2020) (Proof shortened by AV, 7-Aug-2025)

Ref Expression
Hypotheses usgrexmpl.v 
|- V = ( 0 ... 4 )
usgrexmpl.e 
|- E = <" { 0 , 1 } { 1 , 2 } { 2 , 0 } { 0 , 3 } ">
usgrexmpl.g 
|- G = <. V , E >.
Assertion usgrexmpl 
|- G e. USGraph

Proof

Step Hyp Ref Expression
1 usgrexmpl.v 
 |-  V = ( 0 ... 4 )
2 usgrexmpl.e 
 |-  E = <" { 0 , 1 } { 1 , 2 } { 2 , 0 } { 0 , 3 } ">
3 usgrexmpl.g 
 |-  G = <. V , E >.
4 1 2 usgrexmplef 
 |-  E : dom E -1-1-> { e e. ~P V | ( # ` e ) = 2 }
5 3 eleq1i 
 |-  ( G e. USGraph <-> <. V , E >. e. USGraph )
6 1 ovexi 
 |-  V e. _V
7 s4cli 
 |-  <" { 0 , 1 } { 1 , 2 } { 2 , 0 } { 0 , 3 } "> e. Word _V
8 2 7 eqeltri 
 |-  E e. Word _V
9 isusgrop 
 |-  ( ( V e. _V /\ E e. Word _V ) -> ( <. V , E >. e. USGraph <-> E : dom E -1-1-> { e e. ~P V | ( # ` e ) = 2 } ) )
10 6 8 9 mp2an 
 |-  ( <. V , E >. e. USGraph <-> E : dom E -1-1-> { e e. ~P V | ( # ` e ) = 2 } )
11 5 10 bitri 
 |-  ( G e. USGraph <-> E : dom E -1-1-> { e e. ~P V | ( # ` e ) = 2 } )
12 4 11 mpbir 
 |-  G e. USGraph