let G be _Graph; :: thesis: for G1, G2 being Subgraph of G st the_Vertices_of G1 = the_Vertices_of G2 & the_Edges_of G1 = the_Edges_of G2 holds
G1 == G2
let G1, G2 be Subgraph of G; :: thesis: ( the_Vertices_of G1 = the_Vertices_of G2 & the_Edges_of G1 = the_Edges_of G2 implies G1 == G2 )
assume A1: ( the_Vertices_of G1 = the_Vertices_of G2 & the_Edges_of G1 = the_Edges_of G2 ) ; :: thesis: G1 == G2
A2: ( dom (the_Source_of G1) = the_Edges_of G1 & dom (the_Source_of G2) = the_Edges_of G2 & dom (the_Target_of G1) = the_Edges_of G1 & dom (the_Target_of G2) = the_Edges_of G2 ) by FUNCT_2:def 1;

now

let e be set ; :: thesis: ( e in the_Edges_of G1 implies (the_Source_of G1) . e = (the_Source_of G2) . e )
assume A3: e in the_Edges_of G1 ; :: thesis: (the_Source_of G1) . e = (the_Source_of G2) . e
then (the_Source_of G1) . e = (the_Source_of G) . e by Def34;
hence (the_Source_of G1) . e = (the_Source_of G2) . e by A1, A3, Def34; :: thesis: verum

end;

then A4: the_Source_of G1 = the_Source_of G2 by A1, A2, FUNCT_1:9;

now

let e be set ; :: thesis: ( e in the_Edges_of G1 implies (the_Target_of G1) . e = (the_Target_of G2) . e )
assume A5: e in the_Edges_of G1 ; :: thesis: (the_Target_of G1) . e = (the_Target_of G2) . e
then (the_Target_of G1) . e = (the_Target_of G) . e by Def34;
hence (the_Target_of G1) . e = (the_Target_of G2) . e by A1, A5, Def34; :: thesis: verum

end;

then the_Target_of G1 = the_Target_of G2 by A1, A2, FUNCT_1:9;
hence G1 == G2 by A1, A4, Def36; :: thesis: verum