let G1, G2 be _Graph; ( G2 .allComponents() c= G1 .allComponents() implies G2 is Subgraph of G1 )
assume A1:
G2 .allComponents() c= G1 .allComponents()
; G2 is Subgraph of G1
now ( the_Vertices_of G2 c= the_Vertices_of G1 & the_Edges_of G2 c= the_Edges_of G1 & ( for e being set st e in the_Edges_of G2 holds
( (the_Source_of G2) . e = (the_Source_of G1) . e & (the_Target_of G2) . e = (the_Target_of G1) . e ) ) )hence
the_Vertices_of G2 c= the_Vertices_of G1
by TARSKI:def 3;
( the_Edges_of G2 c= the_Edges_of G1 & ( for e being set st e in the_Edges_of G2 holds
( (the_Source_of G2) . e = (the_Source_of G1) . e & (the_Target_of G2) . e = (the_Target_of G1) . e ) ) )now for e being object st e in the_Edges_of G2 holds
e in the_Edges_of G1let e be
object ;
( e in the_Edges_of G2 implies e in the_Edges_of G1 )set v =
(the_Source_of G2) . e;
set w =
(the_Target_of G2) . e;
assume
e in the_Edges_of G2
;
e in the_Edges_of G1then A3:
e Joins (the_Source_of G2) . e,
(the_Target_of G2) . e,
G2
by GLIB_000:def 13;
then reconsider v =
(the_Source_of G2) . e as
Vertex of
G2 by GLIB_000:13;
set H = the
plain inducedSubgraph of
G2,
(G2 .reachableFrom v);
the_Vertices_of the
plain inducedSubgraph of
G2,
(G2 .reachableFrom v) = G2 .reachableFrom v
by GLIB_000:def 37;
then reconsider v9 =
v as
Vertex of the
plain inducedSubgraph of
G2,
(G2 .reachableFrom v) by GLIB_002:9;
e in v .edgesInOut()
by A3, GLIB_000:62;
then
e in v9 .edgesInOut()
by GLIBPRE0:44;
then A4:
e in the_Edges_of the
plain inducedSubgraph of
G2,
(G2 .reachableFrom v)
;
the
plain inducedSubgraph of
G2,
(G2 .reachableFrom v) in G2 .allComponents()
by Th189;
then
the
plain inducedSubgraph of
G2,
(G2 .reachableFrom v) is
Subgraph of
G1
by A1, Th189;
then
the_Edges_of the
plain inducedSubgraph of
G2,
(G2 .reachableFrom v) c= the_Edges_of G1
by GLIB_000:def 32;
hence
e in the_Edges_of G1
by A4;
verum end; hence
the_Edges_of G2 c= the_Edges_of G1
by TARSKI:def 3;
for e being set st e in the_Edges_of G2 holds
( (the_Source_of G2) . e = (the_Source_of G1) . e & (the_Target_of G2) . e = (the_Target_of G1) . e )let e be
set ;
( e in the_Edges_of G2 implies ( (the_Source_of G2) . e = (the_Source_of G1) . e & (the_Target_of G2) . e = (the_Target_of G1) . e ) )set v =
(the_Source_of G2) . e;
set w =
(the_Target_of G2) . e;
assume
e in the_Edges_of G2
;
( (the_Source_of G2) . e = (the_Source_of G1) . e & (the_Target_of G2) . e = (the_Target_of G1) . e )then A5:
e DJoins (the_Source_of G2) . e,
(the_Target_of G2) . e,
G2
by GLIB_000:def 14;
then
e Joins (the_Source_of G2) . e,
(the_Target_of G2) . e,
G2
by GLIB_000:16;
then reconsider v =
(the_Source_of G2) . e as
Vertex of
G2 by GLIB_000:13;
set H = the
plain inducedSubgraph of
G2,
(G2 .reachableFrom v);
the_Vertices_of the
plain inducedSubgraph of
G2,
(G2 .reachableFrom v) = G2 .reachableFrom v
by GLIB_000:def 37;
then reconsider v9 =
v as
Vertex of the
plain inducedSubgraph of
G2,
(G2 .reachableFrom v) by GLIB_002:9;
e in v .edgesOut()
by A5, GLIB_000:59;
then
e in v9 .edgesOut()
by GLIBPRE0:44;
then A6:
e DJoins v,
(the_Target_of G2) . e, the
plain inducedSubgraph of
G2,
(G2 .reachableFrom v)
by A5, GLIB_000:73;
the
plain inducedSubgraph of
G2,
(G2 .reachableFrom v) in G2 .allComponents()
by Th189;
then
the
plain inducedSubgraph of
G2,
(G2 .reachableFrom v) is
Subgraph of
G1
by A1, Th189;
then
e DJoins v,
(the_Target_of G2) . e,
G1
by A6, GLIB_000:72;
hence
(
(the_Source_of G2) . e = (the_Source_of G1) . e &
(the_Target_of G2) . e = (the_Target_of G1) . e )
by GLIB_000:def 14;
verum end;
hence
G2 is Subgraph of G1
by GLIB_000:def 32; verum